A few receiver reviews

From its humble beginnings back in 2004, when I started publishing short evaluations of the shortwave receivers that were crossing my way, this page has steadily grown and now includes other kinds of radios as well. This reflects in the table of contents, but the ordering on the page is currently purely chronological, and you may find the occasional inconsistency due to the varying age.

By the way, should anyone feel like sending me radios for review, I am quite unlikely to resist. ;)

Contents

About my shack

Shortwave portables and luggables

Domestic portables (without explicit shortwave focus)

Walkman-type AM/FM stereo radios

Clock radios

Antennas

Misc.

Station profile

Here is some information about my 'shack', so you have an idea of the conditions under which I usually test receivers.

Sony ICF-7601

(Sample obtained used, some time in 2003.)

This is a ca. 15 year old pocketbook-sized analog portable with MW, various shortwave bands (most of them are dual conversion) and FM. I noted the following on my 7600 series page, comparing the 7601 to my trusty ICF-SW7600G:

All in all, while the ICF-7601 is a somewhat mixed bag particularly when it comes to strong signal handling, it's a decent analog travel portable that still is a lot better than the el cheapo single conversion stuff you get new for its used price these days (I paid around EUR 20 plus shipping for mine). Some were supposedly not well aligned from the factory and thus not that sensitive, this doesn't seem to be the case here. In fact, mine is a bit too sensitive for what the mixers can handle. BTW, it really shines on 60 meters.

What struck me is that in some parts of the world (such as Azerbaijan or Malaysia) this receiver still seems to be available (as of Oct-2003), in spite of production officially having ceased ten years ago.

Here are some noise / buzz spectra recorded in 2008:

While the set is lacking the extensive audio filtering on the preceding ICF-7600A, good 10 kHz suppression and so-so 5 kHz suppression are achieved even in MUSIC. Things get about bulletproof (as far as travel portables slightly below a "digital" '7600 go) in NEWS.

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Sony ICF-SW12

(Sample purchased used, ca. 2003/2004. S/N 53681.)

The ICF-SW12 is a combination of an alarm clock with a little analog shortwave receiver, a cute little gadget if you ask me (though a bit overpriced when new – I got mine used at a bargain price). The receiver circuitry had been suspected to be closely related to the ICF-SW20/22's (which in turn is a slightly stripped-down version of the ICF-7601's) – but as a simple oscillator frequency search showed, it is just a single conversion unit. My performance observations:

To sum it all up, if you're a passionate SWL and need a matching clock radio or if you want a compact clock radio with acceptable shortwave performance for travelling, the ICF-SW12 fits the bill. (If you can live without an integrated clock and alarm, better choose the ICF-SW20/22 with dual conversion on shortwave, which reportedly provides noticeably better performance. These models, however, lack the 22 and 60 meter bands, which is too bad particularly in case of 22m.) It's not what you'd use for serious DXing, but OK for getting the big guys, and of course the concept is pretty unique. However, it's not exactly a winner in terms of price/performance ratio.

(If more serious shortwave performance at comparable or even smaller dimensions is needed, the ICF-SW100 may be worth a look, or even the – now discontinued – ICF-SW07. Naturally these are also much more expensive. If it needn't be quite as small but still very compact, an ICF-SW35, Sangean ATS-606 or Degen DE1102 (under whatever brand name) may fit the bill at a reasonable price point.)

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Grundig Signal 700

A rather unknown, all in all pretty ordinary Grundig portable from the mid '70s. Since this is not a serious shortwave rig, criteria are ordered somewhat differently now.

JFTR: S/N 53681.

A fun application for a radio like this with a tape/phono input is playing back online audio streams (hey, it still beats a crappy 2.1 system with the mids sucked out). The signals will have to be downmixed to mono, but at least with Winamp that is not a problem. Availability of DIN-to-RCA adapters might be one, depending on where you are located.

There is also an entry for this radio over at radiomuseum.org. It quotes 5 AM and 8 FM circuits, which is hardly exciting for a transistor set. The Signal 500, however, featured 7 AM and 10 FM circuits, just like the normal stationary radios of the day, and thus must have been better reception wise in spite of the smaller number. (Maybe this was a case of "circuitry recycling" to allow longer production runs, given there had been some models with the same circuitry in preceding years.)

What the number of circuits says? These comprise resonant circuits on both RF and IF level (including LO circuits), so this allows only a very rough estimate of the performance level. If the distribution is known (schematic or educated guesswork), you can say something about how good IF-level selectivity and RF-level sensitivity and overload might be. (For example, a Satellit 1000 features 13 FM circuits, with 2 in the front-end, 1 in the oscillator, 10 on IF level including 2 in the ratio detector. Of interest to us are 2 in the front-end and 8 on IF level.) Finally, you need numbers for receivers with known performance for comparison. (Good transistorized FM tuners from the 60s had like 15 or 16 circuits. My guess for a 16 circuit unit would be 10 for IF filtering and 3 for front-end filtering. A tube tuner would have like 12 circuits.) Please note that numbers for tube and transistor rigs are not directly comparable (why?), also it's not trivial to compare LC circuits (#LC) to ceramic filter elements (n) – it seems to be roughly #LC = 1.5...2 x n, with things depending on Q achieved (for LC) and the ceramic filter types which are not all created equal either.

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Philips (Magnavox) D1835

The D1835 is a pocketbook-sized portable (about 1 cm wider and 0.5 cm deeper than an ICF-7601, with disregard to the tuning knob) covering, at least in the /02 version I have, LW, MW, FM and the shortwave broadcast bands from 49m through 11m, including 21/22m. It was apparently introduced in 1984, probably being supposed to compete with the smaller Grundig Yacht Boys of the time; manufacturing was in Hong Kong. In the late 80s, it retailed for $70US list price, costing only about half as much as an ICF-7601.

The circuitry: two gang FM tuning (1x front end, 1x osc), FM mixer with a bipolar transistor (instead of a FET like on the Sony ICF-7600A), one FM IF filter (7600A had two) plus a tuned IFT, single conversion on shortwave with tuned front end (with LC and not crystal controlled oscillators that are a bit drifty; IF is 468 kHz), SW mixer with one FET; AM filtering with one 2-element ceramic plus apparently a tuned IFT in front of the AM detector; the used ICs are a PC1018C for AM mixing (LW/MW mixer, SW 2nd mixer) and AM/FM IF work and a BA526 as mono audio amp.

The D1835 appears to be fairly unknown in spite of its decent performance (more on this later) and thus frequently does not get any bids at all when offered for auction here in Germany (which doesn't happen too infrequently). I was able to obtain one in very good condition in its original packaging with the accompanying soft carrying case and all the docs including the manual and a tinily printed small schematic sheet for next to nothing – quite a bargain compared to the used prices of said Grundig competition (which is not likely to perform much better, also being single conversion units). In fact, the RF circuitry is extremely similar to a Yacht Boy 650's (even including the AN7218S, apparently a PC1018C equivalent) which, however, is 2 to 3 years older. (Feature wise, a Yacht Boy 300 would be about the equal of the D1835, minus band coverage – the Grundigs only cover 49, 41, 31, 25, 19 and 16 meters, but then came out a few years earlier as well. Grundig also offered models with clock functions and later even frequency counters, while Philips had nothing comparable.)

Overall I'm quite pleased with this little set. It's not the world's greatest DX machine, but a solid performer nonetheless, with an excellent price/performance ratio (given you can snag one in good condition for, say, ≤ 10 EUR). I particularly like the good sound and low noise level during speaker playback.

My own grey D1835 carries a S/N of KT 03083023095 (whatever that means). The second sample, a blue one, is # KT 0370300012.

Manuals for other Dxxx radios (not including the D1835)

The approx. 1988..1990 D1875 features a virtually identical arrangement of connectors and controls combined with more modern styling and a decently sized flip stand. I wouldn't be overly surprised if the internals turned out to be very similar or even identical to those of the D1835, at least it appears to be based on the same NEC PC1018C IC.
On a side note, there seems to be a non-name D1875 knockoff of dubious origins that has a mirrored dial scale, i.e. the shortwave bands on the left. Now given that the original isn't too high-tech to begin with, I guess a copy needn't perform a lot worse. Strange stuff!

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Sony ICF-SW7600

(Sample obtained used in June/July 2004. S/N 301101.)

Intro

With some rigs you always wonder how they might perform, without actually ever getting round to trying one. Well, for me, the ICF-SW7600 was such a rig. In 2004 I was finally able to obtain one, unfortunately in need of repair as it turned out. Fortunately I was able to find someone who is a lot better in these things than I am, and after a non-trivial repair session my SW7600 was working (almost) like new. Eventually other problems cropped up, however, and it was time for a total recapping... but more on that later.

The ICF-SW7600, introduced in 1990, was Sony's replacement for the older ICF-7600DS, which had been little more than an optically updated ICF-7600D (first presented in 1983 and with some notable interior changes in 1985) to begin with and therefore was getting a bit old. It's a portable in the popular pocketbook size class, measuring an official 19.1 x 11.8 x 3.2 cm and weighing 615 g with batteries. The actual front is no larger than for the predecessor, but they cheated a bit and had the controls on the right-hand side stick out to allow for a larger circuit board size. The case is almost all (ABS) plastic, with a metal loudspeaker grille, as also found on a number of other "7600" models. It's held in sort of a blue-greenish dark grey. For catching the waves, a telescopic antenna (68 cm in length) with slide-out base is provided, plus an internal ferrite rod antenna (15 cm long) for MW/LW. The speaker driver installed is an 8 cm (3") job. A wrist strap is attached at the top left.

This set, which uses a PLL frequency synthesizer, tunes the AM ranges from 150 kHz to 29995 kHz continuously (coverage is limited in some areas) and the FM broadcast band from 76 to 108 MHz (starting at 87.5 MHz for a number of areas; stereo reception provided via headphone jack). Tuning steps vary from 3 kHz on longwave over 9 kHz on mediumwave to 5 kHz on shortwave, with FM being tuned in either 50 or 100 kHz steps, depending on band coverage (!). SSB reception with sideband (preference) selection is possible on the AM bands (not for Saudi Arabia model). Tuning is entirely keypad based, with up/down buttons, direct frequency entry (via a telephone-style numeric keypad) and search tuning facilities being available. On the AM ranges, analog fine tuning is available for AM and SSB modes. Clock and timer functions are provided. A total of 10 memory presets store both AM and FM frequencies. There is an LC display for showing frequency or time that can be backlit momentarily.

An external antenna input is provided on many but not all versions (my German model excludes it). There's not only a headphone out but also rec out (mic-level) and remote control jacks. There is a flip stand on the back to allow for a tilted position. A two-position tone switch (NEWS / MUSIC) is provided. This model was the first to include the sliding on/off button which in the "LOCK" position will keep the set from inadvertantly powering up.

Supplied accessories included an AC adapter (e.g. AC-240), carrying case, stereo earphones, the AN-61 reel antenna and an antenna adapter for coaxial cable (provided the set has an input), along with the usual documentation like user manual and the "Wave Handbook", which contains information on shortwave listening.

For the technical details on the set, check out its listing on the Sony 7600 series page.

Now, how does it perform when contrasted with my faithful SW7600G? I used the original Sony AC adapter for the SW7600 and the usual universal regulated one for the SW7600G, as well as rechargeables in both.

Build quality

Operation

Performance on the AM ranges

FM reception

Probably in part due to the shorter aerial, sensitivity on FM seems noticeably lower than on the 7600G. (That was when the latter was still unmodified. A badly matched 150/110 kHz IF filter combo can work wonders in terms of reduced sensitivity and bad distortion on weak stations.) The stereo threshold is even more so, allowing for more consistent but also more noisy stereo reception. As mentioned before, I liked the tone quality even though highs are a tiny bit lacking (which certainly is not the fault of the LA3335 MPX chip – which is still used in the 7600GR today – but the audio circuitry that follows it). (Interestingly enough, the measured frequency responses on FM merely show the 7600G's rolled-off low end as a difference, while highs filtering is just about identical.)

Battery usage

Not evaluated properly yet. Still prior to recapping, my sample seemed to be straining its batteries somewhat, in spite of a specified quiescent current that hardly exceeds 60 mA; possibly there were some higher-frequency fluctuations (with somewhat dead electrolytics, things won't get any better either). As in the predecessors, no low battery warning is provided - however, a double pop noise when turning on points to a low voltage. The set still runs off only 3 volts, which should make for optimum battery usage but may be critical for rechargeables.

Misc.

Too bad my SW7600 (German model) does not feature an external antenna input jack, it would certainly be fun to try the AN-LP1 with the thing. (In fact, I tend to forget this once in a while, proceed to set up the AN-LP1, and then am disappointed each and every time again. Man, I hate those useless regulations, especially since the ones in question just vanished shortly after this model came out. OK, what are the poor Italians supposed to say... On the other hand, nowadays we could use some more enforcement of EMI regulations, otherwise how could things like plasma TVs with massive RF radiation have been sold?)

The screw that holds the telescopic antenna is flush with the rear and can easily be touched when holding the set, thereby degrading reception due to capacitive coupling. The succeeding model has a recessed screw.

The rec out jack really is mono only (confirmed by schematic). Probably this is because output level is very low and only suited for a mic input, as on previous sets (later models have a full-blown line out, as does the more upscale ICF-SW55). The rec out precedes the active filtering stage, so there should only be a first-order lowpass in action there. There is a REMOTE jack which can be used to turn on matching Sony tape recorders (TCM-27 and TCM-77, with PC-261M adapter; TCM-25 with optional remote unit RM-43), possibly others as well.

Conclusion

All in all, the ICF-SW7600 is a nice shortwave portable with good sensitivity, selectivity, strong signal handling, so-so image rejection and good sound that is well suited for broadcast reception and usable for SSB (reception is good, it's just not that much fun with 5 kHz steps) – as long as it works. The electrolytics used back then are the Achilles heel of this receiver, and non-working samples aren't particularly rare. See Failures and Repairs for details.

Notes

As of early 2009, my ICF-SW7600 was out of order again – this time, the left output channel no longer wanted to cooperate. Ah well, yet another dead-o-lytic™... Thanks to Helmut G. Vogel for recapping the set (for free!), who found that the old electrolytics were measurably dried out, just like on other samples he was fixing at the same time. Thankfully the board showed no corrosion damage (just some electrolytic deposit), unlike on another "patient".

It is interesting to note that in order to achieve even the relatively large tuning steps by todays's standards, a trick was necessary – see "Tuning step trickery".

Audio noise spectra

Some audio noise spectra (recorded shortly after those for the RD1220):

Looks like audio filtering consists of a 2nd-order lowpass, with additional first-order low- and highpass filters (or a bandpass) activated in NEWS. For reference: The SW7600G's response in MUSIC looks like the SW7600's in NEWS, albeit with a flatter passband and steeper filter skirts, and switching to NEWS only attenuates the highs even further! (Admittedly the changed highs response in MUSIC seems to be mainly due to a tighter filter.) No wonder I generally prefer the older model's (less "communications-grade") audio, the tone control has a greater effect as well.

A note on the AC-240

That is a pretty usable power supply. Unloaded voltage in the SW7600 is about 6.5 volts (6.6 measured directly), which drops to about 5.7 V with the SW7600 on FM and 5.6 V on AM. This is in the 240V setting on 230V mains, values are higher in the 220V setting. It's only "semi-regulated", but does a pretty good job in the RF department, which usually is more important for a receiver.

Update: I took a peek inside (easy), and it looks like it's actually an unregulated job. Rather compact construction, PCB shows about a dozen solder joints. A small ceramic capacitor was spotted at the rectifier, so it seems it uses some of those in order to quieten down the diodes. The main filter capacitor is a 2200/10V Rubycon. Unloaded voltage was closer to 7.0 V this time, or 7.7 V in the 220V setting. Very little mechanical transformer hum, very low idle power draw. Sensitive-ish headphones (HD590) on SW7600 reveal low-level hum, but at this point amplifier hiss is a bit annoying anyway, and resorting to a headphone amplifier (FiiO E11) drops both of these to inaudible levels.

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Sony ICF-M60SRDS

Parents can be difficult people to deal with, particularly when looking for a "kitchen radio" for some news in the morning and such. My favorite was the Sangean WR-1, but, being a fully analog set, its feature set does not include RDS which was desired; also, the retro look did not appeal much. (Too bad, since the thing has the reputation of giving excellent reception.) It's quite amazing how rare RDS support is among ordinary portable radios, Grundig and Sony are about the only two companies offering portables with RDS. In the end, the decision was between Grundig's Concert Boy 80 and Sony's ICF-M60SRDS. The Grundig looks ugly IMHO, so we went with the Sony.

The ICF-M60SRDS – a version ICF-M60LRDS with longwave instead of shortwave coverage (albeit only with 9 kHz steps, problematic in case of 177 kHz DLF and 183 kHz Europe 1) also exists – is a mid-sized domestic portable in a "neo-retro" design featuring MW (9 or 10 kHz steps), SW (5 kHz steps) and FM (50 kHz steps and display to .1 MHz, with RDS) coverage. It either operates off mains or off 4 'C' cells (R14). Aerials include a pretty long rotatable whip and a built-in ferrite rod, an external antenna connection is not provided.

Overall, this radio does what it's supposed to, namely receiving local FM stations and occasionally MW stations as well. Incidentally, I assume it's based on the internals of the ICF-M760/770.

Update: This has now been replaced by an under cabinet kitchen radio for space reasons, a 15EUR job from a local discounter. For the price that one is far from bad, but sound is even less exciting than before. I have been eyeing a Grundig Sonoclock 890 as a replacement.
Pulling out the ICF-M60SRDS again, FM selectivity seems to correspond to one 280 kHz filter plus an IFT, MW sensitivity is up there with the best (no worse than the ICF-7600A) and selectivity better than average, and sound, while showing the speaker driver size, still is too honky for my taste – the old Grundig Sonoclock 670SP clock radio with its 10 cm speaker manages to outclass the Sony in terms of tonal balance. Maybe it was intended to compete with the Sangean PR-D3(L) (/CCRadio) which also appears to be tuned for the vocal range. Whatever, not my cup of tea.
We ultimately sold this one.

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Degen DE105

(Sample obtained used, early 2005.)

Intro

This little Chinese made, truly pocket-sized PLL synthesized radio (only about 11.0 x 7.1 x 2.0 cm, which is smaller than even a Sony ICF-SW20/22) with MW, SW and FM coverage hasn't been available here in .de for too long (as of early 2005 – the rebrand has been discontinued for a while now). Nonetheless I recently (2005) stumbled across a somewhat used sample which I was able to obtain for roughly half new price. Apparently someone at Technisat considered the model interesting enough to start selling a rebranded version (with English lettering, of course) as Viola WR1, together with the (presumably original) earbuds also found in the Kaito KA105 version, two AA batteries, an instruction leaflet and a little station frequency brochure. At an affordable EUR 29,99 list price, you do not expect any wonders – yet, what you get is a well-built, if not to say sturdy little radio with good fit and finish (including the Al alloy front known from the KA105 and buttons with short travel and good tactile feedback) and reasonable performance. (The cuteness factor is also pretty high.)

On shortwave, which is covered from 5950 to 15600 kHz in 5 kHz steps, the set is single conversion with an IF of 450 kHz (sometimes these images are really good for something ;). MW, with the default 9 kHz steps, ranges from 522 to 1620 kHz, while FM reaches from 87.5 to 108 MHz (unusually only in 100 kHz steps).

Whoever decided to cover 49m down to 5950 kHz and 19m up to 15600 kHz only clearly didn't have much experience with shortwave. It wouldn't have been dramatic to cover 5850 or 5800 to 15800 kHz instead. (To be fair, the DE105 was one of Degen's first shortwave portables. Maybe they'll do a little refresh once.) The rather limited overall coverage probably has its roots within a varactor tuned front-end with not infinitely variable resonant frequency (little more than a factor of 3 is usually achieved, maybe because MW requires just that?), which presumably is also responsible for the split shortwave range on some other entry-level single conversion sets. That's about the only way to establish some image rejection on a single conversion receiver, and as a welcome bonus strong signal handling (mostly 2nd order intermodulation) is improved as well.

Shortwave sensitivity

The DE105 clearly uses front-end tuning, as indicated by the decent image rejection for a single conversion set and some hand sensitivity. It can't handle big antennas like the AN-LP1 in strong signal areas, but sensitivity appears to be decent even on the whip (with little overload problems), with the usual headphone antenna trick also being present (same goes for an external power supply, which may introduce all kinds of noise that way – but hey, who would use a receiver like that on AC?).

AM selectivity

Selectivity on all bands is quite OK given the price, but still the set struggles with 9/10 kHz separation, giving the once-typical hets on many stations (when compared to the ICF-SW12 or D1835 which aren't that much better up to roughly 10 kHz distance, particularly the filter shape factor and ultimate rejection aren't that great – strong stations can still be faintly heard up to 30..40 kHz away, while my reference ICF-SW7600G with its ~7 kHz 6-element ceramic filter only makes garbled audio heard 5 kHz away from these and shows no trace of them a few kHz further; in one extreme case a very strong station which caused slight scratching on the ICF-SW7600 up to 15 kHz away could still be heard up to 50 to 55 kHz away in varying intensity, clearly a spurious/ultimate rejection issue).

AM audio

Audio on AM lacks bass and is rather bright-sounding; some lowpass filtering would have been good to reduce annoying wideband noise. The cheapo filtering is definitely the biggest drawback of this receiver, but to be fair it is certainly not alone with this problem in its class. The synthesizer seems rather noisy (background noise sounds grainy somehow, and when zero-beating the oscillator signal in SSB on another receiver, noticeable hum components are present, while an LC or crystal generated signal from another receiver sounds perfectly clean), as is the AF amp with 'phones connected.

Internally generate interference

As has been noted before, some internally generated buzzing is present on MW; apparently the P shielding is not very good (actually, when taking a peek inside I didn't see any) and the ferrite rod catches the stray radiation. This is also noticeable on SW with the whip fully retracted, but virtually disappears once it's extended, unless you touch the antenna that is.

FM

FM shows adequate sensitivity. Selectivity is a mixed bag, as it is unsymmetric – stations disappear much more quickly when tuning below their nominal frequency than above it. So in some cases 200 kHz separation works pretty well and in others 300 kHz of distance still isn't quite enough.

Audio

Audio frequency response seems to have a slight mid-to-highs hump, but is quite good otherwise – the DE105 is certainly not bass shy and additionally I see little reason to complain about L/R separation in FM stereo. When the set is cold (and I mean cold, as in whatever temperature there is in my rucksack when temps outside are below 0C), it exhibits considerable bass distortion, which disappears once it's warmed up (looks like crummy electrolytics in the audio section). The supplied earbuds are pretty decent actually, rather mid-highs centric but at least not with extremely crummy frequency response or high distortion (Sony MDR-101, anyone?). Ah yes, speaker audio is just what you expect at the size, i.e. nothing even resembling bass. The ICF-SW12 is no better in that regard either. At least the frequency response reduces the volume of 10 kHz hets.

Misc.

Internals

What you find inside the receiver is not exactly SMD parts galore, at least many parts seem to be conventionally-sized (and I guess cheaper) ones, thus restricting the level of integration. It's all pretty packed, of course. (2008 update: Through-hole parts one one side of the PCB, surface mount stuff on the other, that's how it's commonly done with these sets.) As I mentioned, there wasn't any obvious shielding to be seen on the microprocessor board.

Also read: RadioIntel review
a review in Chinese with nice pics, interior included (the same in Google translated Chineseglish)

It almost looks like a bigger (and probably better) AM filter had originally been planned (CF3) but this hadn't made it to production. *grmbl* (Incidentally, the wide filter position in the '1101 and '1102 looks the same. This should also fit a 4-element filter, e.g. Murata SFP or similar.) You can also see the CD8132GP IC the receiver is based on, apparently a Chinese equivalent of a Toshiba IC (TA8132AN).

Conclusion

The bottom line? If you want a small radio with a small price tag but still halfway decent shortwave performance and good battery life for lugging around (e.g. in a shirt pocket), you may want to consider this one. If you want the best reception for the money, I would not recommend it (AM selectivity is just too much below par), but if you're looking for better performance in this kind of size, choices are few and prices non-negligible.

Back in early 2005 or thereabouts, I wrote:
"My primary use for the WR1 (DE105) is some listening (mostly FM) while on the bus, with the stock earphones. It's pretty hard to beat this combo in terms of space taken up, though I'm happy when I can comfortably listen to a decent hi-fi FM tuner like my venerable Onkyo T-4650 via the HD 590s at home again. Shortwave sees mostly some DW and BBC reception, which is OK while underway, but again at home different equipment is preferred."
Oh my, how things have changed. These days, the DE105 spends its life in the asssorted radios drawer – performance is just too much below what I like to see.

Possible alternatives

Audio noise spectra

Here are some noise / buzz spectra that I took on the DE105 in 2008:

FM doesn't look half bad, deemphasis seems to be close to what it should be for 50 s. AM shows the expected rather large bandwidth and modest filter shape factor.

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Philips (Magnavox) AE3405

(Sample purchased used, ca. 2005. S/N KT 039410038021.)

Intro

The AE3405 is a little pocket-sized set with analog tuning covering the shortwave bands from 49m through 11m including 22m with dual conversion (4.52 MHz (4.50 MHz on mine, aging?), 468 kHz), along with MW, FM (stereo) and, in the /23 version which I have, the tropical bands (called TB) from 120 through 60m with single conversion (which, BTW, are received via the ferrite rod, as would be LW in /00 and /20 models).
At 12 x 7.5 x 2.7 cm and a weight of 170 g, it basically is a somewhat larger version of a Sony ICF-SW20 with much better band coverage (pretty much the equal of an ICF-7601 when it comes to the number of bands) and FM stereo included.
It runs off two AA cells or an external 3V DC (center negative).
This model dates from the early '90s, around 1990...1993 (the manual available online is dated 09/1989, the service manual hints at 1990). The design is based upon the Sony CXA1238M AM/FM stereo IC.

My sample was obtained cheaply due to its condition (last two antenna segments broken off but present, case in average shape), no mention of the model number and "Philips" being misspelled (it was pure luck that I saw the auction at all). Fortunately the rather unique design makes identification by picture an easy task.

Reception, 49m through 11m:

Reception, MW

Sensitivity is somewhat behind the ICF-7601, presumably due to the smaller ferrite rod. (Spec: 3.5 mV/m for 26 dB S/N.) Directionality also is a bit worse for the same reason. Still, not bad at all. The DE105 has no chance competing here.

Reception, TB

The usually rather strong 75m stations could be picked up with no trouble in the evening. Sensitivity on 60m proved to be noticeably inferior to the ICF-7601 which covers that range with its dual conversion part and the whip antenna (remember that the AE3405 uses the ferrite rod). For some strange reason, touching the whip with the tip of the plug of the Sony AN-LP1 (which wasn't even turned on but unfolded and put together) helped sensitivity on 60 and made a number of stations heard noticeably better or at all. (Maybe using a ferrite antenna coupler with some wire antenna would give good results as well.)
It be noted that tuning can be ridiculously difficult here due to the wide frequency range crammed together.

Reception, FM

Audio quality

Battery life

The AE3405 is reputed to be pretty thrifty on batteries, and given the circuitry it should be.

My original tests showed much worse sensitivity on FM – well, these presumably still pretty full alkalines only had 1.15 V left (i.e. 2.3 V total), and the FM section does not work exceptionally well under low voltage conditions. (Don't laugh – are you really sure this wouldn't have happened to you?) Reception on the AM ranges, however, appears little different even with fresh batteries.

Build quality

It's not a Sony, and that shows. The AE3405 indicates "Made in P.R.C.", i.e. it was produced cheaply in mainland China. The case with decent fit and finish isn't all that sturdy and tends to creak if you press on it, the front part has developed a crack above the tuning knob. Overall, not exactly awe-inspiring. Other AE3405s were apparently produced in Hong Kong. (Looks like /20 and /23 models were made in China and /37 in Hong Kong.)

Conclusion

The bottom line: A small receiver with a good feature set and great potential on shortwave (the concept is better than Sony's with the variable 1st IF around 10.7 MHz which makes the 2nd mixer prone to overload) but only so-so build quality, dial calibration and sensitivity. Overall, I like mine.

Notes

Now that I have the service docs I'm even more impressed by how much radio was squeezed into the thing (though it's also obvious where they had to cut corners – still, it's a minimalist but elegant concept). At the time this was only topped (by quite a margin) by Sony's ICF-SW1, which was a real feat of miniaturisation back in 1988.

Need a user manual? Or some service docs?

Audio noise spectra

Some audio noise spectra (recorded shortly after those for the RD1220):

My, the DBB is one heavy loudness EQ. Without that, response doesn't look too far off for 75s deemphasis. I did not get sensible results in AM, apparently hiss levels are too high.

Philips part numbers

At least in those days, Philips did not use the common nomenclature of the type of part indicated by a letter followed by a number (e.g. C169), but a 4-digit system with the first digit indicating the kind of part. I found myself scratching my head when I first saw this, so maybe the following table is of use to someone:

Interpreting 4-digit Philips part numbers
Number Possible parts
1xxx, other Misc. parts (mechanical, loudspeaker etc.)
2xxx Capacitors (incl. variable)
3xxx Resistors (incl. pots and jumpers)
5xxx Coils incl. ferrite bars, filters
6xxx late 80s: diodes
7xxx early 80s: all kinds of semiconductor devices; late 80s: transistors, ICs, no diodes

Grundig Ocean Boy 204

It'll leave my shack again soon, but maybe some notes are appreciated. A 1963/1964 classic, it covers LW, MW, SW from 2 to 20 MHz in 3 bands and FM. Single conversion, LC filtering throughout, fully solid state. Oval wideband speaker, supposedly 2-way (switching in tweeter does not make a difference though), great sound for a portable though some more highs couldn't hurt; S/N so-so. Sample not in too bad a shape, except for two shortwave bands being dead and FM dial cord stringing being wrong (tuning backwards). FM not too sensitive but sufficiently selective, LW/MW sensitivity behind the usual 7600s but nevertheless decent (selectivity is also usable, and I didn't notice any overload presumably due to the front-end tracking; good directionality with the large ferrite rod). Not at all deaf on the working shortwave band (fortunately the most interesting middle one), but very prone to overload. Hey, it was built for '60s signal levels, with '60s transistors (bipolar only, of course, and maybe still partly germanium equipped). Technology has come a LONG way since then. No idea in what way a realignment would have helped performance, but it's certainly a good idea with a set this old. Overall, nice collector's item, but as such not great for a bargain hunter.

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Panasonic RF-B20

The RF-B20 is an analog travel portable of the smaller kind, approx. 17 × 9 × 3 cm large, which was sold in the second half of the '80s for approx. $140US (list) and maybe $110-130US regularly (not exactly a bargain).

The version RF-B20L sold in Europe features LW, MW, SW (in 6 bands: 49m, 41m, 31m, 25m, 19m, 16m) and FM. The front says "SW Double Superheterodyne", internally this is the same concept with a 1st IF of 10.7 MHz that we already know from Sony, with the same advantages (e.g. frequency stability) and disadvantages (wide 1st IF bandwidth and thus limited dynamic range).

The front and top of the case are held in black painted brushed Al (nice) while the rest of the case is plastic; fit and finish can be called good. The set runs off 3 AA batteries (or rechargeables, for that matter). The loudspeaker apparently is a 66 mm type. Special features? A DX/Local switch (here to be found on the back) is not commonly seen on receivers like this, while the classic HOLD slider is more widespread. As usual with Panasonics, the carrying pouch is attached at the bottom of the left side of the receiver. More unusually, the whip antenna, which can be pulled out a bit like on various Sony models, finds itself attached at the top right (left is more common). What is not present (yet) is a stand on the back.

Overall, while you're unlikely to be able to chase DX with it, the RF-B20 makes a decent travel companion (as long as you can live without 22m coverage). It wasn't exactly cheap in its day for what it does (but keep in mind that the number of smaller dual conversion portables was very limited at the time, actually I can only think of the Sony ICF-4900/4910 and the internally identical ICF-5100, which were a good bit smaller still; the RF-B20 looks like somewhat of a "me too" product to counter the '4900), but you can see where some of the effort went. It's nothing you'd spend big bucks on these days. Modern equivalents include Sony ICF-SW35, Sangean ATS-606A/S and Degen DE1102.

Note: This set appears to have non-negligible battery drain when off.

JFTR: S/N 8ABWB43755.

Taking a peek inside (no, I'm not curious, I just want to know :P), you find a 12 cm long ferrite rod, an AN7236S IC and some dial cord mechanics, much more isn't apparent from the back.

Receivers like this frequently suffer from scratched and/or dirty plexiglass dial covers, since not everyone treats radios that well. Display polish as used for mobile phones (essentially a very fine-grained polishing paste) together with a soft cotton cloth helps here. Be sure to tape off the fringes of the cover carefully, since you don't want to ruin any other surfaces.

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Panasonic RF-B11 vs. Sony ICF-SW11

(Samples obtained used, ca. 2005. ICF-SW11 S/N 1089638, RF-B11 S/N EH4GB001383.)

Intro

Well, originally I just wanted to upgrade my portable listening setup to something a bit more capable and less battery hungry (not that the DE105 would be a battery hog for a PLL set, but a plain ol' analog is hard to beat in terms of battery life), then I happened to see a few auctions for brand new RF-B11s, won one, well and then I got a used ICF-SW11 at a good price, too. The perfect opportunity for a little shootout of these quite similar radios, don't you think?

Features

Both are 12-band analogs covering LW, MW, SW (in 9 bands from 60m through 13m) and FM stereo. Both feature a flip stand on the back, but only the Sony has a battery door loss prevention band attached at the battery door. In return, the Panasonic features tone (high/low) and mono/stereo switches and a stereo indicator while the Sony does not. Both have a carrying strap attached at the bottom right, and both run off either 2 AA (R6) cells or 3V DC.

Look and feel

FM reception

Sound

Shortwave reception

LW/MW reception

Both have their share of strange whistles on LW. The whip antenna noticeably affects LW reception on the RF-B11 but has little effect on the ICF-SW11. Selectivity on MW and LW is usable but 9 kHz hets are not uncommon when the band is crowded. Daytime MW sensitivity is approximately the same on both and does not differ too much from the ICF-7601, but a weak test station was disturbed by some kind of het (mixing product maybe) on the ICF-SW11.

Misc.

It may be worth noting that the RF-B11 is made in Taiwan, possibly by Sangean (which makes the RF-B33 and RF-B55 as well). The ICF-SW11 is being made in China, IIRC.

Conclusion

The verdict? None of our contestants comes out without a few ruffled feathers, but overall I like the more full-featured and more FM-friendly Panasonic better. Only an audio mod would be in order. The Sony is somewhat better suited for shortwave due to its higher sensitivity there, but failed to impress me on FM.

Notes

BTW, the RF-B11 currently (as of 2005, ed.) constitutes my mobile listening setup together with a (slightly modded) Beyerdynamic DT 231 PRO. Both have been holding up well in over two months of use. (I keep the RF-B11 in a small plastic bag to fend off scratches, seems to work.) I usually leave the tone switch in LOW, as the cans are a bit on the bright side to begin with. (Didn't really help, now looking for something with better isolation and less brightness. AKG K26P looks promising.) The receiver does not like being operated near stronger FM transmitters and will show overload in form of very strong 3rd order IM 100...200 meters around these even with just the headphone cable used as antenna. (Unfortunately that affects the station I'm usually listening to quite badly. Fortunately I don't live there.) Admittedly these are rather extreme conditions which would cause many other receivers to stumble as well.
2008 update: Both RF-B11 and DT231Pro have long since been retired. The aforementioned overload is present, to slightly varying degree, on basically all my sets with only a band filter in front of the FM RF amp.

Audio noise spectra

Here are some RF-B11 noise / buzz spectra recorded in 2008 (the SW11 has been sold):

There is this low-frequency rolloff that is always present. FM deemphasis doesn't look too bad though. The AM filter isn't a shape factor king, as expected.

A technical comparison

When looking at the schematics of RF-B11 and ICF-SW11, they are actually quite similar. Both are based on CXA1238M (RF/IF) and CXA1522M (audio amp), neither has a protection diode against DC voltage reversal. AM selectivity is one 2-element ceramic filter + IFT for both.

The differences are in the details – the Sony has an amplifier stage after the AM IF filter while the Panasonic doesn't (explaining the difference in sensitivity), in return the RF-B11 has two FM IF filters where the ICF-SW11 has to make do with one (and apparently noone bothered to align the stereo decoder VCO properly on the sample I owned). There is an extra transistor dedicated to tuning LED drive in the Panasonic, and the lean bass area is easily explained by smallish coupling capacitors. The FM band filter is of the discrete (L/C) type in the ICF-SW11, while the RF-B11 has a monolithic ceramic filter.

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Sony ICF-SW30

(Sample obtained used, ca. 2006. S/N 108182.)

Intro

This receiver, the grandfather of the current ICF-SW35 and introduced in 1993, was known for good reception at its price point (little more than half of the price for an ICF-SW7600G) paired with only so-so ergonomics. Well, curiosity finally got the better part of me and I snatched one up inexpensively.

Look and feel

The black all-plastic (but nonetheless very sturdy-feeling) case of the ICF-SW30, which was produced in Taiwan, is almost as large as that of a typical "7600" (and a bit thicker) at 16.9 x 11.1 x 3.5 cm, which forms quite a contrast to the rather minimalist front panel controls (of which the frequently needed ones are fairly large) and few elements on the sides. Hmm, don't we know that stand on the back? Yup, this is very similar to the one found on the ICF-SW7600G, but a tad larger still. The whip antenna (approx. 60 cm in length) looks exactly like the one of the ICF-SW11.

Features

Ergonomics

Reception

Sound

Speaker sound is on the bright side with the smaller speaker (66 mm), but still fun to listen to... more so than the 7600G, which someone once described as tinny and muffled at the same time, a description hitting the nail right on the head when comparing the two. No idea what whoever did the audio engineering on the 7600G had been smoking. On the headphone jack, the audio is very warm and bassy, sounds like noticeably overdone deemphasis. This does go well with notoriously bright headphones though, and probably tames the internal speaker as well.

On a side note, I have found the Beyerdynamic DT231 to give good synergy with radios like the ICF-SW30 (and others with the same sonic signature, e.g. SW11), which nicely tame the otherwise excessive brightness of these cans.

Battery life

The ICF-SW30 apparently isn't too much of a battery hog, with a 30% longer spec'd battery life than an ICF-SW7600 on only three AA cells. (Quiescent current is given at an economic 25 mA on MW, 30 mA on FM and highest at 50 mA on shortwave. The big difference is not surprising, after all it's basically a 1-chip receiver on MW and FM and uses quite a bit of additional circuitry for shortwave. Anyway, that still is about 10 mA less than for the SW7600.)

You have to be fairly quick when changing batteries, as the set won't keep its settings much longer than a minute with them removed.

The verdict

It's hard to go wrong with this one if you find it cheap – for around 15 EUR or even less (something approaching 20 would still be OK, too) there's not much better to be found in terms of raw SW reception, which is near perfect for a travel radio. Operation, however, is the weak spot of the SW30 and may cause considerable frustration if you tune around a lot. The way the muting is implemented, it seems silly to have it used during tuning – less generous use of muting would at least have saved the users from the annoying noises accompanying this. (No idea why they didn't catch that one during testing.)

If you were content with the level of performance provided but would like to have something significantly more comfortable with better frequency coverage thrown in, look at the Sangean ATS-606A/S, the ICF-SW35 or the Degen DE1103 (rebranded as e.g. Kaito KA1103 and already playing a class higher with a dual balanced mixer, switchable IF bandwidths and SSB – the closest ICF-SW30 equivalent would be the DE1101, and the more fancy DE1102 is not too far off either).

Notes

Back in the olden days Radio Netherlands used to have a review of the ICF-SW30 in their Receiver Shopping List. It got lost during their big site revamp in 2004, but I happened to still have a very old copy downloaded back in '98.
Radio Netherlands ICF-SW30 review.

Audio noise spectra

Some audio noise spectra (recorded shortly after those for the RD1220):

These are fairly similar to the ICF-SW7600's which still was a current model at that time. Calling the SW30 a "baby SW7600" wouldn't be too far off.

ICF-SW30 Internals

With the service manual having become available online, it turns out that "baby SW7600" is spot on. The shortwave circuitry is very similar, including the CX20111 FM/AM IF IC, though the FETs used in amplifier and mixer stages are run at lower currents and some are less expensive types, and the filter on the lower first IF is a wider ceramic rather than a crystal type. No wonder the set is a pretty good performer on the short waves. The AM IF filter appears to be the same type found in its successors. A PD1724G microprocessor and PLL IC is used, the same one also found in the SW7600G a bit later.

Examining the offending muting circuitry, it seems this was just a stupid (maybe last-minute) design. Muting momentarily pulls electronic volume on the CXA1522M audio amp down, with no declicking of any kind. Not even the capacitor used for suppressing volume pot scratchiness can do much about it, since the collector of muting transistor Q10 is connected on the wrong end of series resistor R50. Later models not only used a switching transistor with an integrated base resistor and a collector connection on the other end of said series resistor, most importantly they also added a 1 F ceramic capacitor between base and ground. (I would have tried 100 nF or so.) It should be easy to retrofit one if you are halfway comfortable with surface mount components, as the area isn't crowded and a grounded tab for the volume pot retainer is right nearby.

This receiver has also been modified for DRM reception.

Upon taking a look inside to clean up the DX/Local switch, I sighted not only the CX20111 (later followed up by the functionally identical CXA1111M and CXA1611M in Sony's semiconductor product portfolio) but also the CXA1522M audio amp. The chips' date codes seem to suggest a 1996 production date, which would indicate a fairly late sample – looks like this model was far less popular than e.g. the ICF-SW7600G. Internal construction is reminiscent of the contemporary 7600s but a little different again; mechanically the ICF-SW40 appears to be very similar.

Related models

The direct successor to the SW30 (apparently produced in the same factory in Taiwan, but "made in Japan" samples also exist) was the 1997 SW40, which was a good bit more comfortable while still not costing a fortune. As far as I can see, reception circuitry is identical in the ICF-SW35 and ICF-SW40, which both are dual conversion throughout the AM range (thus no frontend tracking on MW and possibly worse image rejection there) and share the same kind of 1st mixer (not dual balanced, unlike the SW30). It's ironic that the old ICF-SW30, the rx with the least inviting operation of the bunch, has the most advanced shortwave reception circuitry. That's tradeoffs, I guess...

The more expensive ICF-SW33 apparently behaved pretty much the same reception wise (while using a somewhat safer but unusual 1st IF of 21.44 MHz) and had a low-level rec out and more sophisticated clock functions (who really needs those?) including two standby memories thrown in. It also remembers the last frequency on each SW band and shows the meter band received. In addition, the speaker gets a metal grille and the whole rx actually is quite a bit smaller at 16.57 x 9.3 x 3.05 cm. Looking at a photo it seems that it was made in Japan. Like the SW30, the SW33 apparently wasn't too much of a battery hog even if specified battery life ran closer to the SW7600's – someone managed to squeeze out 50 hours of (non-continuous) operation with alkalines. This model used to be fairly expensive for the reception provided and thus never was too popular. (Ironically the other rx with a 21.44 MHz 1st IF that I know wasn't too exciting either, the Sangean ATS-505.) It seems like the somewhat newer ICF-SW30 (1993 vs. 1992) was intended to provide a downsized version with almost equally good reception at a much more attractive price.

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Sony ICF-7600D

Who doesn't remember it, the classic that started it all? (Well, maybe the folks over the pond who got to know this one as ICF-2002.) Back in 1983 the appearance of this compact digital dual conversion portable made quite a splash, and for good reason. Until then, the best you could get in this kind of size (184.5 × 118.5 × 32 mm according to the manual) were "dual conversion light" receivers like the ICF-7600A with a 4-element ceramic filter for AM and 2 filters for FM, with more modest models dominating, but here you have a true dual conversion receiver (with a high 1st IF of 55.845 MHz at that) with a dual balanced first mixer, 6-element IF filter and all of the convenience that a PLL based set offers. Even SSB and CW reception is possible with something product detector-ish, and an external antenna input is included in many models. In short, basically a full-blown portable SW receiver shrunk to pocketbook size, and generally better performing and more reliable than the preceding ICF-2001 at that. No mean feat. Unsurprisingly they sold like hotcakes and reached more than 100,000 sold units in 1983 already.

Overall, I found it quite interesting how little the raw reception performance in AM had changed since the mid '80s; however, SSB reception has greatly improved since then, and current models also feature more presets and synch detection.

JFTR: S/N 378330.

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Toshiba RP-20

This page hasn't seen any updates in a while, but as it happens, radiophilia struck again and my collection has grown a bit. First in line is this mid-'80s Walkman-style portable FM/AM radio with FM stereo. I bought it because I found myself using the radio function of my trusty Cowon iAudio G3 MP3 player (the G3/K26P combo being my usual portable audio source with – FM radio recordings), which, not being the most sensitive, struggles with reliable stereo reception of my favorite FM station during the daily bus rides, and that annoyed me quite a bit. (Apparently this is related to the Philips all-in-one radio chip with minimal external parts count used, which is an amazing feat of integration but seems to have its quirks.)

The Toshiba RP-20 is on the larger side compared to current portable audio gadgets, the brick-like radio (pretty much all plastic) measures some 11 x 5.9 x 2.1 cm (add about another 7 mm in thickness for the belt clip). It is intended for headphone playback only; the headphone cable also serves as FM antenna, while AM is received via an internal ferrite rod. The visual appearance screams 1985 (which apparently is this model's vintage – actually the service manual is dated May 1984), the tuning dial on the front for example reminded me of the Sony ICF-4900. A stereo indicator LED is integrated within. Two sliders on the side permit choosing a reception mode from FM stereo, FM mono and AM as well as enabling a high-cut filter with the TONE switch engaged. The top holds the power switch as the third and last slider, tuning and volume adjustment are done via two thumbwheels, and last but not least there's the headphone jack. The back provides a belt clip and the battery compartment for two AAA cells. It may be interesting to know that assembly was in Korea, the price tag in the States was $20 (about $35 today). With my RP-20, I also received a matching Audio Technica carry case made of robust artificial leather.

Hey, really not bad. Might be a candidate for a filter mod (180, maybe 150 kHz), I'd just have to find out how to open the thing (the back seems clipped on, no screws there – ah, there is one hiding under the removable belt clip). If there is something to complain about, it would be that the AM section with its pitiful overload rejection could have been left out and some more effort invested into the FM section instead (another ceramic filter plus IF amp, maybe).

In comparison, the NIB Grundig City Boy 10 (late '80s, around 1990 perhaps?) that I also bought fared a good bit less well – the channel separate volume sliders are somewhat dodgy and could use a bit of contact cleaner, audio on FM seems to include a bass boost, AM audio shows limited bass response and FM selectivity appeared to be yet worse than on the Toshiba. The red version does, however, look neat, and the included earbuds featuring rather large drivers (I would have guessed 12 mm diameter) sound rather decent indeed, as far as I could judge that without matching foamies (the ones supplied have crumbled to dust due to age). The City Boy 10 was made in Hong Kong.

Being the curious nature that I am, I had to take a peek inside the RP-20 – after undoing the screw, you can lever off the back at the 4 "tabs" with a small flat screwdriver. The interior is all conventional (no SMD thankfully), even if slightly cramped. There's a small ferrite rod no more than 5 cm in length mounted horizontally (as seen in normal operating position, meaning the radio is higher than wide), which makes sense. ICs are TA7687AP and TA7688P plus some MPX chip in SIP that I unfortunately couldn't see properly (the service manual revealed this to be a TA7342P); I could spot a single ceramic filter (E10.7A, blue dot left = ordinary 280 kHz type, 10.67 MHz center freq).

Once I had the service docs, I could only be amazed once more: For its performance level, the circuitry actually is fairly simple. The FM frontend reminds me of what I've seen in Grundig Sonoclock alarm clocks (which admittedly tended to have pretty good FM parts, see below), it employs two tuned (variable) RF circuits (1x pre mixer, 1x osc) plus two fixed resonant circuits in front of the RF preamp and self-oscillating mixer (can give good performance when carefully optimized for dynamic range, as strong signals may cause detuning or even "blow out" the LO signal), for which bipolar transistors in common base topology are used.
A (tuned) IFT follows to support the ceramic filter, but before that we have a bipolar transistor in common collector topology, which I'd assume to be employed as an IF amp but which strangely is used in saturation (base-collector voltage greater than zero) – it could be, however, that base and collector voltage are reversed, at least this would make sense when looking at where the supply voltage comes from (originally a regulator output on the TA7687P). So assuming this is correct, it still looks to have a frequency-selective feedback path. Yikes – I guess I still need to learn a few things about minimalist circuit engineering.
AM filter wise, there is a single tuned IFT plus a second LC circuit, which makes it hardly surprising that selectivity isn't too great there. A standard 2-gang frontend is used, RF amp and mixer are contained within the TA7687AP. There are various capacitors used for lowpass filtering but I haven't spotted a dedicated deemphasis circuit. The output coupling caps are 100 types, a bit on the smaller side for 32 ohm headphones and candidates for replacement by 220 ones.
BTW, the service manual is dated May 1984.

Here's some food for the "send pix!!!" crowd: :p

JFTR: S/N 5XS3009304.

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ITC Julia

Wanted: Operating Instructions for Tramp WE-100 or this set! – Suche immer noch Anleitung (wegen Schaltplan) zum Tramp WE-100 oder diesem Gert!

The large analog multiband portable once sold as ITC Julia, HGS Tramp WE-100 or Super de Luxe Globe 100 in West Germany seems to be a slightly stripped-down version of the Unitra Eltra Julia Stereo from Poland (naturally the "export version" does not bear any notes on its origin), which was made from about 1979 to 1991 as far as I was able to find out.
At 41.5 x 25 x 11.5 cm and more than 5 kg of heft, it's on the larger side of things as far as portables go, more like luggable (with the handle on top). It currently makes the largest such radio in my collection.
Noteworthy features are 5 presets for FM, bass and treble controls, a long telescopic whip the upper part of which can be tilted to utilise its directionality on FM (certainly inspired by what Grundig used), TA in/out and TB out as DIN jacks (and the input seems to be a "true" DIN input, i.e. current input with very high source impedance on the output instead of the transitionary voltage input / voltage output interpretation common in the West) and a similarly oldschool speaker output; the Polish model also featured FM stereo reception and an external antenna input.
Power input is from mains via a "figure-8" Telefunken jack or from ~12V DC via one of the usual round jacks (same as in ICF-SW7600 and other older Sony models). Something rather confusing is that the main power switch (?) on the back operates differently than one would expect – pressed means power *off*. (Turns out this is a mains/battery switch.) I already had the back open and was looking at the clean interior with neat cable routing and all (the build quality certainly is on par with that of other reputable makes, you do notice a traditional radio manufacturer there) and determining the resistance of the two fuses which of course were perfectly fine. Duh! Oh, and do unclip the plug connecting a cable at the back of the battery compartment.

I like this set. It's not quite as good as it could have been, but it's a solid radio that is young enough to be frequently available in good working order on the used market (apart from the FM sensitivity issue, the dirty SW tuning cap and a good bit of dirt that had to be removed, my set has no scratchy pots or other stuff like that), and with its somewhat exotic origin certainly is worth having for a collector. It also shows a few pitfalls of solid-state shortwave receiver designs as they were common up to the mid to late '70s.

In terms of innards, the Julia is definitely a child of the mid/late '70s, it just has to make do without the latest goodies like frequency counters, and seemingly semiconductor availability did not include FETs (something already noticed with GDR-made sets). Unlike some more "serious" models, it only covers a few widely spread bands on shortwave, but at least this leads to good frequency stability there. It's a pity that my sample doesn't work as well as it could. The more I look into this set, the more impressed I am.

Elsewhere on the web I found information about this model having been built by Pathé-Marconi in 1975/76 and sold for 349 DM, but neither is the IF of 460 kHz correct nor does the manufacturer seem very likely, already having been mainly in TV production at the time and apparently preferring somewhat unusual IFs of 472 or even 480 kHz. With the schematic of the Polish set matching this one very well, this theory can safely go to the circular file.

A small note found in the battery compartment of my sample states "JULIA ITC", "86 02" (production date I assume) and a serial number of 01391.

Servicing information on the Unitra Julia Stereo has recently appeared on eserviceinfo.com; the closest to a schematic of the Tramp WE-100 that I found was this (argh!) – man, I'd kill for a scan of that thing (well, maybe not, but you get the idea). Even with the different schematic style and low-resolution pictures the similarity to the Polish set is obvious.

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Sony ICF-7600A

(Sample obtained used, ca. 2006. Cereal number 269624.)

Intro

If you're familiar with my 7600 pages, then you'll certainly also know this classic model. As a compact shortwave portable with good reception and rather thrifty battery usage, it was quite popular in its day. So how does it fare today? I'll compare it to the later and less costly ICF-7601 with a similar concept.

On a side note, mine came with possibly the oldest alkalines I've seen in the last few years – some Sony branded ones still stating "Made in W. Germany". These must be some 15 years old at least, and they even still were at over 1.4 V per cell and hadn't leaked or anything (which I guess is directly related to the former)! The foam on the battery compartment door didn't hold up equally well, but that seems to be a common problem after that much time.

The receiver itself had apparently been gathering dust (literally) laying on its back for quite some time, there even is some on the tuning dial! It took some patience and a toothbrush to get rid of the stuff in trickier places. Thankfully, apart from a slightly scratchy volume pot, occasionally intermittent NEWS tone switch position and a whip antenna needing the occasional screw tightening (basically the same problem as on the ICF-7601), the set is in fine working order.

Build quality

It's a SONY. As to be expected from an ancestor of the ICF-SW7600G, this is a solidly built radio, right down to the controls, the pull-up telescopic whip with a ring for inductive coupling at the tip (copied with the D1835) and the off switch doubling as a hold slider. There is some creaking when pressing on the top, but otherwise the case is stable. As later models, it features a metal speaker grille. The only thing missing is a stand on the back, and the SW band indicator fields could have been larger.

SW reception

MW reception

FM reception

FM is quite (though perhaps not extremely) sensitive, and the selectivity with the two IF filters also is very usable, only the AFC seems a bit hyperactive. Dial accuracy seems fairly good, as far as that's to be judged on the somewhat cramped scale of a model starting at 76 MHz.

Sound

AC-456C PSU

With the receiver, I also obtained a matching AC-456C power supply (even says Made in Germany, wow). While the multimeter showed an unloaded voltage of little more than the desired 6 V, indicating a regulated PSU, results with the ICF-7600A (or the 7601, for that matter) were not good. MW was quite badly disturbed with periodic ticking (buzzing) noises that I'd attribute to the rectifier. Taking a look inside, what I suspected turned out to be true: No small capacitors across the rectifier diodes to be found, so these will have to be added for the PSU to be of any use; otherwise quite solid construction. In the meantime, the AC-240 obtained with the ICF-SW7600 (and subsequently used with a number of other receivers as well) proved to be working very well.

Conclusion

The verdict? The ICF-7600A(W) may be a bit outdated (a few more bands would have been good, particularly 22m and possibly 60m), but still is a good performer in both reception and audio quality. It's anything but surprising that this model sold well in its day. Modern-day receivers with similar concepts include the Tecsun R-9700DX and Degen DE1107; if anyone would happen to own either of these and ye olde 7600A(W), I'd appreciate some information on how they compare.

Audio noise spectra

Here are some noise / buzz spectra recorded in 2008:

As you can see, audio filtering is quite heavy indeed (no wonder things are slightly muffled), but that contributes to a very good AM selectivity.

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Grundig Sonoclock 900

The Sonoclock 900 is a fairly fancy FM-only clock radio of 1997 vintage. The clock is radio controlled (via DCF77 in this case), you get a fancy fluorescent display that displays the clock to 1s along with the date (or volume), FM preset and some alarm-related stuff and neatly dims according to ambient brightness.

The radio itself is pretty much all analog, the presets are done like in vintage Euro tuners (you have a pot on the back to adjust the varcap tuning voltage for each preset), just switching is done electronically. The receiver is based on a CXA1019S IC and uses a 2-gang plus bandpass FM frontend, which isn't fancy, but IF filter wise you find two 150 kHz ones! A combo DCF77/FM antenna attaches to the back via some strange DIN jack.

I assume the SC 900 wasn't exactly cheap when new, but clock radios seem to be a bit out of fashion these days so one can pick up good stuff for little money on the used market.

The Sonoclock 900 is a far cry from the screechy mess with very modest reception that el cheapo clock radios can be. Sonic and reception performance actually mattered when this was constructed, something that does not seem to apply to comparable Sony products for example. If you happen to see a Grundig clock radio of the fancier kind on the used market (and there were quite a few), don't hesitate to give it a closer look, even if the appearance particularly of 25+ year old models can be a bit funky.
Incidentally, the service manual for the Sonoclock 900 is available on the web.

Upon opening my sample to fix some nasty whine that I suspected to come from the transformer, I found that some electrolytics had apparently leaked. That doesn't speak for the quality of those and might account for the occasional hum. The set does get quite warm in operation, so that may be responsible for accelerated aging. When replacing caps, I'd use 105 types. BTW, the inside is a bit crammed, no SMD anywhere in sight but quite a few wires. When assembling and disassembling the thing you may find yourself in need of 3 hands.
The aforementioned whine only appears when the built-in buzzer has been used and persists thereafter. I've only been able to work around this by using radio alarm only.

A more ordinary mid-90s clock radio is the Sonoclock 750 – it only has two manually selected brightness steps for the display and a smaller speaker in a more conventional form-factor, but at least tuning is far more easy and you can also set the clock without having DCF reception. Not bad in reception and sound, but the small speaker does have its limits.

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Grundig Sonoclock 670SP

The '670SP is a clock radio of 1981 vintage, made in Grundig's factory in Portugal like most of them. Uniquely, it features speech output of the time via a UAA1003 IC. As it would have been impossible to store the large excitation / residual stream in an IC back then, only the LPC coefficients were stored and the resulting speech is metallic but perfectly understandable. (The version sold here in Germany used the -1 version of the chip, there were -2 for French and -3 for English as well.)

The FM-only receiving section is similar to many other better Sonoclocks around that time, with two frontend gangs (varicap tuned to provide 8 presets), a self-oscillating mixer (still a common sight even in upper-class portables around 1970, can give good performance when carefully optimized for dynamic range) and two ceramic IF filters. Reception performance accordingly is quite good, with decent sensitivity and good selectivity.
Setting the presets (memostat/preostat) can be done very precisely as there are many (almost too many) turns from one end of the band to the other.

Setting the clock can be a bit of a pain as adjustments only go forwards, but at least one can reset the time to 00:00:00 by pressing >>, > and SEC at the same time. Either radio or buzzer alarm is possible.
There is a baseline brightness adjustment for the clock display, additionally the brightness is adjusted dynamically according to ambient lighting as measured with a photo diode.

The form-factor of the set is somewhat clunky (as to be seen on the cover page of Grundig's Technische Informationen 5/6-'81 – I wouldn't be able to fit it on my nightstand) but it enabled the use of a 10 cm speaker which gives phenomenal sound for a clock radio, making the '900 (no slouch to begin with) sound fairly honky and tinny in comparison. It's true, they don't make 'em like they used to... (Admittedly I haven't heard a SC890.)

My set isn't quite flawless, still operating in OFF mode (but turning off in either of the alarm modes) and apparently lacking a red acrylic window in front of the clock display. The crackling noises in the audio seemingly disappeared when I cleaned out all the dust inside. At least I have the service docs, as I managed to obtain a whole folder with vintage Sonoclock service information for little money. (For this clock module, however, there seem to be some discrepancies between schematic and PCB layout.)

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Sony SRF-M40W

The SRF-M40W is a PLL synthesized FM/AM Walkman radio that came out in 1988 and, like many such portable audio devices of this or a greater age that weren't the cheapest in their day, is rarely seen on the used market. It enjoys a very good reputation for FM (and to a lesser extent, AM) reception performance, so does it live up to the hype?

The verdict? This is a very good little radio for FM (particularly if you're in the States) which unfortunately is plagued by rather high amp hiss levels when used with today's portable headphones (/earphones/IEMs). An attentuator such as the one suggested above may help but it may not be that easy to find one that is sufficiently rugged and does not alter the sonics significantly (such as a simple series resistor or pot). Can it claim do be the best such radio? I have yet to obtain an old SRF-40W or -30W, but considering that the SRF-M40W apparently doesn't employ the correct deemphasis time constant for this part of the world and is quite hissy, I would hesitate to award it the best.

JFTR: S/N 104185.

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Roadstar TRA-2350P (Redsun RP2000)

(Sample obtained new, Sept. 2006)

Intro

Redsun Electronics is a fairly new name on the field of shortwave receivers with a factory in Dongguan, China that also produces mini hi-fi systems and boomboxes. The models RP2000 and RP2100 are clearly targeted at the Tecsun BCL2000/3000 a.k.a. Eton/Grundig/Lextronix S-350(DL), the only difference between the two being that the 2100 features 10 presets for each of the 5 bands and has keypad-based tuning and scanning. The Roadstar TRA-2350P which can be bought for about 60 EUR is a rebrand of the RP2000. The RP2100 is also being sold as the Elta 3569 "GLOBESTAR" (typically 70..80 EUR), and on the other side of the pond you can buy a Kaito KA2100 (typically US$129).

The RP2000, measuring 29 x 18.5 x 7 cm (W/H/D) and weighing in at 1.8 kg, is not the smallest set you'll find, but still a nice size that allows comfortable operation and good sound via an apparently 12 cm (5") speaker. The PLL synthesizer employing a tuning knob tunes MW in 9/10 or 1 kHz steps (either 522 to 1620 kHz with 9 kHz steps or 520 to 1710 kHz with 10 kHz steps), shortwave in 3 bands (1711 – 10010 kHz, 9990 – 20010 kHz, 19990 – 29999 kHz) with either 5 or 1 kHz steps and FM (87.5 – 108 MHz) with 100 or 10 kHz (!) steps. It features external antenna inputs (male coaxial PAL jack – 75 ohm for FM, 50 ohm for SW – and 500 ohm wire posts for MW), an IF output for AM (!), a 5-step signal strength indicator, can be run off either AA or D cells in addition to mains (230V/50 Hz in this case) or DC in, and on the AM ranges is a dual conversion set (55.845 MHz / 455 kHz) with two selectable IF bandwidths and an RF gain control. Bass and treble controls are also provided, and you can have either local time or UTC displayed (even during reception if necessary). Quite an impressive feature set at this price level. Accessories supplied in this case were a mains lead and two simple adapters for connecting coaxial cable.

Note: There are reports of apparent cost-cutting in newer samples, specifically left-out shielding for the P board and FM frontend. This seems to affect RP2000s manufactured January 2008 or later at least. Indications are microprocessor interference (whirring noises) on MW and SW plus extremely strong LO radiation on FM (10.7 MHz below tuned frequency, or above if you can't find it; it should be virtually gone 2 or 3 meters from the receiver, while for cost-cutting affected samples reception is still possible 10 meters away).

Operation

MW (AM) reception

FM reception

Shortwave reception

Construction

Generally solid (including the telescopic antenna, an oft-lamented issue with Sony receivers), no real complaints here. The fold-out handle flexes a little, the battery springs could be tighter and I would have liked to see a hinged battery door (I always wonder how people manage to lose these things but it happens), and the knobs feel a little cheap, but this is about it. The set has been knocked over and things have been dropped on it a few times, but so far only the whip antenna has suffered a bit. Nonetheless I'd advise to be careful with the tuning knob in particular so as to avoid damaging the encoder which it's directly attached to.

If you should find that some of the knobs are not running smoothly, pull them out a little – they merely slide on (as with other portables) and are not made with the greatest precision imaginable.

Sound

Quirks, quarks and quibbles

Notes on DRM (Digital Radio Mondiale) reception

Conclusion

Hats off to the engineers at Redsun – this is a really nice radio. One doesn't see a set with consistently high performance regardless of band so frequently, plus it's knobtwiddler friendly (I'll admit right away that I'm not a big fan of nested menu systems and prefer one-control-per-function sets these days), has good audio (the biggest complaint I have about my trusty ICF-SW7600G is that its audio is honky and bass-shy even on headphones, I should really bridge those nasty superfluous undersized coupling caps one day), is generally well made and is very versatile to boot.

Upon closer inspection, it does show a number of shortcomings (partly reminiscent of '70s sets) and compromises made to keep costs down, along with some plain quirks, but taking into account what it does do in its price range I'm not complaining. This set really makes you wonder why receivers of this size are not more common - it certainly improves sound, operation and versatility. Would I recommend the RP2000? For the most part, yes. (Not so sure with one of the newer cost-cutting affected samples though.)

Particularly over here, this set is a worthwile alternative even to normal FM/AM radios – a good performer on both bands it certainly is, particularly regarding selectivity.

Notes

Particularly for shortwave use in areas with crowded shortwave bands filled with strong signals (e.g. Europe, US east coast), I strongly recommend a tunable antenna. I have obtained excellent results with Sony's somewhat hard to obtain AN-LP1, but basically any decent tunable loop of a certain size (why not try building this one?) should give good reception. Even the ADDX-PRE-1, a simple whip antenna tuner / preselector, improves reception noticeably (reduction of overload and improved antenna tuning on the higher bands).

There's a Yahoo! Group for pretty much everything and anything, so it should come as no surprise that there is one for Redsun radios as well. (For inside shots no longer available on the web, check out the files section.)

You can also buy an SSB add-on for the RP2100 (and related sets, of course) named TG37, cost is about $26 shipped to the US. It seems to operate like an oldfashioned BFO, i.e. it generates a carrier with adjustable offset that allows the radio's internal AM detector to make sense of SSB/CW transmissions. Not exactly high-tech but first reports are quite positive.

What's more, a "service manual" (actually a schematic and PCB collection) for the Roadstar unit is available on the interweb. Oh yeah! 8-) Looks like a piece of classic oldschool radio engineering, lotsa standard components but put to good use. They didn't skimp on power buffering either. And of course, there's the usual assortment of not immediately obvious tricks. ;) (Anyone care to explain why they use the AM mixer on the LA1260 in that way? Makeshift IF amp?)
The schematic admittedly isn't the easiest to read, as there are no function blocks marked, usual prefixes on semiconductor components tend to be omitted (e.g. K192 instead of 2SK192, or 4148 instead of 1N4148), smaller capacitors are given in <nne> notation (nn*10^e pF) and there are no DC voltages given. There also is the occasional tpyo (like VRAD being mistyped as VARD), and the AM IF IN pin on the LA1260 being connected to the AGC pin makes little sense, probably the connection was supposed to go to the nearby mixer output either directly or via IFT T17.

I have investigated the intermod problem using some circuit simulation in LTspice (needs files for dual-gate MOSFETs from the LTspice Yahoo! group), and found that:

  1. Maximum gain is quite high, approaching 40 dB in places (with, however, a wide adjustment range as noticed in practical use), and
  2. Gain is reasonably constant across 75m through 11m, with a slight peak around 6..9 MHz – the area with some of the strongest signals in the evening.

Other sets have far less voltage gain, and the input stages of Sony models ICF-SW7600 and ICF-SW7600G also show reduced gain at lower shortwave frequencies. No wonder the poor buffer JFET and/or mixer in the RP2x00 would break into sweat. The Redsun definitely isn't 40 dB more sensitive than those – maybe 20. I guess the rest has to make up for less gain in the following stages. A bit of experimentation with the amp circuitry showed that an RLC network in parallel with RF choke L6 would achieve a nice V-shaped EQ with minimum sensitivity in the critical areas. Might be worth a shot if one can fit it.

Incidentally, a more full-featured model RP3000 with sideband selectable synchronous detection, SSB, keypad input, 1000 presets and air band coverage (!), along with a simpler "export model" RP3100 sans the sync detection and air band, was expected to come out in 2007 but never materialised. Some RP3100 prototypes appeared and one or two were even sold on eBay, but the project was put on hold with the factory being busy enough with OEM production of foreign designs, and as of late 2008 we might never see mass production. There are, however, rumors about a shrunk-down version of the RP2100 design.

Audio noise spectra

Some audio noise spectra (recorded shortly after those for the RD1220):

AM filtering appears to be quite heavy by default in order to provide good selectivity (the low cut, btw, is not present on FM, IIRC there's a smallish coupling capacitor for that), but as you can see the tone controls (which appear to be of the shelving type) can be tweaked to obtain a flatter passband that is easier to listen to, at the cost of some selectivity.

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Toshiba RP-2059

An FM/AM pocket radio almost equal in size to the RP-20 (i.e. about 11 x 5.9 x 2.1 cm), the 1989 model RP-2059 is a PLL synthesized receiver (FM 50 kHz, AM 9/10 kHz, 5+5 presets) with clock and alarm functions. It runs off two AAA cells and in terms of fancy features can offer "DBSS", something I refer to as a "cheesy midbass booster". It's not entirely clear to me when Toshiba stopped making radios, but since I've never seen any post-'80s ones from them I assume this must have been one of their last models.

While the RP-2059 improves on the RP-20 in several respects (AM rejection and EMI sensitivity on FM), there are some annoying ergonomic flaws as well, and you lose some selectivity along with the ability to achieve a hi-fi(-ish) frequency response. Mind you, it would still be on par with or better than a number of current pocket radios of the better kind, but overall it just doesn't knock me off my socks. At that time, pocket radios like this had become common fare (maybe not with alarm, but honestly, that was just late-'80s fashion anyway), and as it happens with mass-market consumer goods, they just don't get as much TLC as when the market is still new.

Ironically, the RP-2059 now is my portable radio of choice to get lugged around along with the trusty iAudio G3. Its sonics fit the Etys quite well, and the improved AM rejection makes the set less fussy on average.

To fix a rattling noise inside, I finally opened up my RP-2059 and took some photos along the way. After removing the screw in the battery compartment, the front part along with the attached PCB can be levered upwards, it's only fixed with several plastic clamps. The microprocessor and main PCB are connected via a ribbon cable on the left side. The set can thus be opened like a book. The P PCB is largely populated with SMD parts, save for some electrolytics, while the main PCB uses all conventional parts. Main PCB area seems to be a bit less than on the RP-20, and IC and air coil count are down. ICs are KIA8132N and KIA7688P, both obviously equivalents to Toshiba ICs and sourced locally. Judging by IC date codes, my RP-2059 might have been a 1990 sample. In terms of FM IF filters, I sighted a 280 kHz type (E10.7A). The ferrite rod is small as ever. Oh, and the little noisemaker was nothing but the piezo buzzer for the alarm function which had come loose – a little solvent-free super glue fixed that. Opening the case expectedly made it a bit more creaky, but it still feels more solid than the Aiwa CR-D6's (below).

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Aiwa CR-D6

The Aiwa CR-D6 is a ca. 1991/92 (the ZZF no. on this German sample tells, older sets would have an FTZ no. and newer ones a BZT no.) PLL tuned FM/AM portable radio much the size of my trusty Toshiba RP20 (about 10.9 x 6.0 x 2.0 cm) that runs off two AAA cells. FM is tuned in 100 kHz steps, MW in 9 or 10 kHz steps (selectable via a switch in the battery compartment). 5+5 presets are provided that can used for either FM or AM stations. A mono/stereo switch is provided, you can also enable a bass booster termed "SUPER BASS" via a 3rd position of the power switch. It looks like a belt clip can be attached but my sample didn't come with one.

The CR-D6 is a bit of a mixed bag. While FM reception and sound aren't bad, it's quite hissy and the pop noise can be annoying.

While my search for the perfect portable FM/AM radio continues, any suggestions as to which ones to look at are highly welcome. ;) (Sorry folks, no DT-200V(X) to be had here in ol' Europe. :( )

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Panasonic RF-3700

This model, also referred to as GX700, has been Panasonic's PLL tuned AM/FM/SW offering in terms of ordinary portable radios since the mid-90s. If my radios had nicknames, this one would be called "The Handbag" – it measures 27.4 x 14.9 x 8.8 cm, weighs 1.1 kg sans batteries (it can be powered by either AC or 4 D cells), and the shape and particularly the somewhat oddly shaped carrying handle remind me of a women's handbag quite a bit. (Admittedly the current Grundig portables can top this by quite a margin.)
The set tunes FM from 87.5 to 108 MHz (in 2 ranges to allow for more stations to be saved) in 50 kHz steps, MW from 522 to 1611 kHz in 9 kHz steps and SW from 5.9 to 18 MHz in 5 kHz steps in my European "EG" version. 8 presets per band are available, for a total of 32. Tuning can be done via either a clicky tuning wheel (a nice touch) or up/down buttons; the latter is generally faster, on SW an additional speed boost is activated after a few seconds (which is needed since there is no meter band choice).
A high/low tone switch is provided, and there's a mono headphone jack, but that's about it for fancy features. Not even the display is lit. There is a mechanical volume level indication, the volume control itself is backwards (i.e. downwards = louder), typically Panasonic.

The verdict? I'm not so sure whether this set is worth the 60..70 EUR it's being sold for, since it receives little better than a handbag, but for its size it does sound very good.

In about 2007, some new Panasonic portables appeared. The RF-3700's successor apparently is the RF-U350. Oh, and "Matsushita Electric Industrial Co. Ltd." is history now, the company is called "Panasonic Corporation" since Oct 2008.

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Philips AE6775

The AE6775 is an unusually styled pocket AM/FM stereo radio that was available from about 2001 to 2003/2004 and costing some 25..30 EUR. The AE6780 was the same with a small speaker built-in. At 7.9 x 7.9 x 1.4 cm, it deviates from the usual form-factor, which is not to say that the rest of the design wouldn't: The buttons on top and display are surrounded by turquoise transparent plastic, the rest of the front is covered by silver painted metal (a thin metal sheet fixed with 4 tiny screws, covering a plastic front that has a taped-over hole for an electrolytic capacitor in it). The buttons are a great example of why painting those in silver is a bad idea – if the paint wears off, it looks like poo. The front is not the most scratch resistant either.
The feature list of the PLL synthesized AE6775/00 is relatively short: AM in 9 kHz steps, FM in 50 kHz, stereo headphone out only, bass booster, 5 presets per band, locking function, time display. The power button (thankfully on top of the radio, along with the preset and tuning buttons) cycles between AM, FM and off. It runs off two AAA cells. The battery door is hinged (great), and when removing the batteries, the LCD is turned off and the clock is stopped, probably to retain memories long enough even with a relatively small goldcap (the difference in microprocessor power consumption with and without LCD can be a factor of 20 or more, several hundred A vs. something in the nA range). There is no belt clip, but the formfactor is quite pocket-friendly (on the downside there's the scratching problem).

Overall, not a bad pocket radio for FM, but somewhat on the hissy side.

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Grundig Music Boy 160

The Music Boy 160 is a ca. 1983 domestic portable with the usual coverage of LW, MW, SW and FM, a fairly ordinary model even in its day. Accordingly, bells and whistles are few – there's a tone control, and you can connect a headphone, that's about it. The set takes 5 C cells and can be supplied from mains, it measures about 28 x 15.5 x 6.5 cm when disregarding the carrying handle. At that time, production of these sets had been moved to the Far East, and quality no longer was what it had been before 1980, when portables were still made in Portugal (or Northern Ireland). I do like the brown/silver metallic paint though, doesn't look half bad.

Not a top performer anywhere, but the sad thing is that today's AM/FM portables aren't really better.

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Panasonic RF-1410L

The RF-1410L, also called GX10II (my sample says RF-1410LBS on the back), was the top model of the about 1980..1984 (or thereabouts) series of AM/FM portables that also comprised the RF-1405L / GX5II and RF-1403L / GX3II. (Presumably other regions got non-L versions.) The preceding series was RF-1110/05/03LBS (GX10/5/3 – a 1978 catalog for Germany only lists the GX5, however), from 1985 onwards the replacing models were RF-1680/50/30L (GX80/50/30). The RF-1680L came out in an era when everything had to be digital and pushbutton controlled, so even the volume control is! (Tuning still is analog; it nominally uses a 2-way speaker, so it certainly is not a bad set.)
The RF-1350BA appears to have been a more upscale mid-70s relative with MW, FM and 3-band shortwave coverage from 1.6 to 30 MHz and a 12 cm speaker that never made it to Europe.

Now coming back to the RF-1410L, this is an AM/FM set of the more fancy kind which covers LW, MW, SW (49m .. 16 m in one band) and FM. It measures about 29 x 18 x 8 cm (officially 28.9 x 17.7 x 8.0 cm), the whip antenna is an impressive 103 cm in length when extended; nominal weight is given as 2.0 kg. Semiconductors include 3 ICs, 1 FET and 8 transistors.
The speaker is a (fake) 2-way system, there's a tone balance (highs) control, fine tuning is available for the AM ranges (though it makes the most sense on shortwave), there's a switchable AFC (the same switch also toggles an attenuator for the AM ranges, but DX and Local should have been reversed), loudness, funny 5-LED tuning indicator (nothing = all 5 lit, then the middle 3, up to a well-tuned station which lights only the middle LED), and if you've already turned off all the other power-consuming stuff, the "battery saver" makes sound more mid-centric to get more mileage out of the 5 D cells in case you're far from a wall outlet (there's a "figure-8" Telefunken jack, and operation from either 220..240 V or 110..125 V is possible). A line in/out is provided via a DIN jack, and there's a mono 3.5 mm jack for speakers and earphones that says 8 ohms only (perhaps they also meant at least 8 ohms?). Sadly there is no dial light.
The whole set feels solid and well-made. (A look under the hood, however, reveals that the ABS plastic isn't extremely thick.)

My sample wasn't in the very best condition and needed some cleaning badly (the dirt that came off smelled like it had been in use in a fries stand, ugh); while it did play, switches and pots were scratchy and intermittent, with the bandswitch only giving good contact on FM, apparently the only band used for quite some time. A good excuse to finally get some tuner spray, which did help (the push switches proved to be tough though).

That was the kind of AM/FM portable I was looking for. It's true, they don't make them like they used to. Ironically, it would be easier to obtain good selectivity and sound today, but nobody does it. Panasonic's AM/FM portables haven't seen a refresh in years, and even the RF-3700 hardly reaches RF-1405L level. One can buy table radios with good sound these days, but I can't think of one with a tweeter offhand. Well, if a proper crossover was too expensive back then, why should this be any better now...

Something I consider interesting is that even after many hours of being turned off, the set still has some voltage left for a brief emission of noise (on FM) when turned on with no mains connected, sometimes it's even sufficient to get some audio of the tuned station. Even after a few days there still is a bit of life left. I guess the big 2200 buffer electrolytic must have seriously low leakage current and thus be in excellent shape for its age, a quick estimate assuming exponential discharge gives something around 1A, probably less. It is not unusual to find new ones with specified leakage currents in the single-digit A range.

Taking a look inside, we find a main board that is smaller than the RF-1405L's, but more crowded, and there's an extra power supply PCB (filled with a transformer, rectifier diodes plus bypass Cs and a fat 2200 10V capacitor). The speakers are made by Mitsubishi (Diatone), as it's apparently still the case with the RF-3700; the low/mid driver is a 12 cm type (EAS_12P83GKG, 8 ohm) and the tweeter a 3 cm (EAS 3PH022A-H, 4 ohm, probably cone). (The lesser RF-1405L had to make do with a single 10 cm driver.) The tweeter is dated "80.5.9". The crossover is simple, a 2.2 capacitor in series with the tweeter. That makes a -3 dB frequency of... 18 kHz?! On to some listening tests. Nice resonance at 150 Hz, I think the case could use some soundproofing and damping and stuff. A sweep shows a fairly even frequency response. 14 kHz still seems to come from the main speaker, same for 15.5 kHz (which is about the maximum for me these days – I used to be able to hear up to 17.5 not so long ago). I would have sworn that directionality in the highs was reduced vs. e.g. the Redsun RP2000 – I love this placebo effect... *grmbl* Anyway, what did they include the tweeter for (and even make sure the baffle is tight around it) if it basically doesn't do anything? Bragging rights? I guess so. The low/mid (or actually wideband) driver seems to perform excellently, but honestly I would have expected a crossover frequency of more like 6 kHz... Perhaps a more fancy crossover was initially planned but then fell victim to cost-cutting – however, I tried 4.7 in parallel to the other capacitor and the tweeter still didn't say much, if anything.
The audio amp is a Sanyo LA4125, with the supply voltage of apparently 9 V off mains it can achieve an output power of up to 7.7 W into a 4 ohm load in bridge mode; into 8 ohms that'll still be at least the 2.4 watts that can be put out in stereo mode into 4 ohms, but most likely more. (Found a catalog scan, this says 4 watts.)
I also sighted one ceramic IF filter, E10.7S, red dot on the left, i.e. an MS2 type with 230 kHz. Assuming that there's another hiding underneath a nearby shielded section, this would explain the selectivity results – the Redsun uses 180 kHz (MS3) types, which are a good compromise between selectivity and price these days.

This is a fairly service-friendly set. Many connections are merely plugged in, and after removing five screws (the reddish ones) you can pull out the receiver chassis. While the bandswitch can be accessed with the chassis in, cleaning the pots pretty much requires removing it. The push switches are tough to clean, as any available openings are very small.

When opening the set for the nth time to apply some contact cleaner, I noticed that one of the standoffs that hold the screws had broken off. Oops – a case for super glue. Don't mix up the screws and do not tighten them too much...

I've modified my RF-1410L with some bitumen damping mat here and there (not too much space inside), and some foam was added to the speaker on 3 sides for damping (thankfully adhesive tape exists). I was, however, unable to get rid of a buzzing resonance in the bass that grows with volume and lower frequencies in a nonlinear manner – either that's the speaker driver hitting its excursion limit, the nearby dial string or the amplifier running out of juice due to unstable supply voltage. Anyway, total weight seems to have increased a bit, and when tapping against the case, it usually doesn't sound hollow. Sonic improvements? I feel like this brought out the highs more and cleaned up some hollowness in the mids. Even before, sound was more detailed than average. Digging out the unmodified RF-3700 and comparing the two, it's no contest.

Inside the battery compartment (which apparently never saw any batteries), there's a hardly readable serial number sticker saying something like 1BCPB08859.

Useful cleaning utilities are a normal and microfiber cloth, some mild detergent and classic H2O, and something that I always tend to forget until I read Jay Allen's RF-2200 restoration article again, an old toothbrush. The venerable dental cleaning tool is highly useful for removing dirt in more obscure locations. In this case, there was some crud in the speaker grille (a wire mesh grille over cloth apparently) that I hadn't been able to remove even when most of the rest was already cleaned up – a wettened nominally soft toothbrush did the trick, for the most part at least, restoring a much nicer look. It was also helpful when cleaning the knobs with their many grooves. The scratchy dial window could be improved with some display polish but still is far from perfect.

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Homebrew AM (MW) loop

OK, so it's not a receiver, being completely passive and all – but for the MW DXer, this is one of the most useful tools available. I have experimented with inductive coupling to tuned ferrite rods inside other radios in the past, with certainly noteworthy results, but this thing should be called "AM loupe". Technically, it's a square box loop with a side length that came out as 94 cm (37"), with 9 windings of fairly thick braided wire (conductor dia. ~ 3.0 mm) in about 1 cm (0.4") distance; it uses one gang of a 2x 500pF + 50 kOhm air variable capacitor for tuning. Yes, that is not exactly tiny and I wouldn't want it to be any larger, but it's hard to beat raw aperture. There's still a bit much paper tape in use, but hey, the looks aren't that important here. The woodwork and glueing took about a day, the whole loop was pretty much finished a day later. Admittedly my dad did most of the work, he's a tad more handy...

The loop tunes about the whole MW band, perhaps one winding could even be removed, but in any case Q doesn't seem to be extremely high (the wire was only chosen because we still had close to 40m of it gathering dust) so it gives a good boost beyond 1.6 MHz and even still on 160 meters. When correctly tuned, the increase in signal strength over using just the built-in ferrite rod of test receivers next to or inside the loop is quite dramatic, I would guess 20 dB or so. (Man-made noise from further away rises equally, of course.) Even notoriously antenna-limited pocket radios grow really big ears at daytime. I had not seen (or heard) something like this before. At the same time, the bandwidth is low enough to improve intermodulation considerably as well. In the evening, the level of a correctly tuned stronger station can be so high that e.g. the Redsun RP2000 is overloaded and distorts. Of course, it is also possible to provoke intermod by mistuning.

The best catch I've had with this antenna was RNE1 from Madrid, Spain on 585 kHz (500 kW) here in southern Germany in the middle of the day in April of 2007. Yes, the signal was very weak and occasionally disappearing into noise, and it is to be assumed that atmospheric conditions were favoring propagation, but I would never have thought that something like this would be possible in the afternoon when one would expect maximum D layer absorption.

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Sony ICF-SW7600G

(Sample obtained new, approx. Mar 1997; S/N 157792)

Intro

This is not just any receiver, it was my first "real" shortwave rig 10 years ago and has been my reference since then.

The ICF-SW7600G is a pocketbook-size portable almost exactly the size of its predecessor – the actual front has become a touch wider so that the controls on the right don't stick out as much, and the speaker grille is a few millimeters less wide, but that's about it. Changes on the inside are more significant: 1 kHz tuning steps are available on the AM ranges, we get synchronous detection for AM (with the additional bonus of sideband-selective SSB demodulation) as a first in this class, and the German version, now a regular international model, finally has official FM coverage down to 76 MHz and an external antenna jack. Reception ranges thus are 150 .. 29999 kHz AM and 76 .. 108 MHz FM.

There also was a change in price tag – this model sold quite a bit cheaper than the previous one, as a number of previously included accessories were left out. The buyer had to make do with only a carrying case and AN-71 windup antenna, plus the usual manual and "Wave Handbook".

For more details on ther ICF-SW7600G, I'll refer you to the Sony 7600 page. So what do I think of its performance these days?

FM reception

This has never been a strength of CXA1376 based sets, and this one is no exception. While sensitivity of a stock unit isn't bad, it overloads easily in high RF environments (use in cities is likely to require use of the attenuator), and with the stock 280 kHz barn doors pretending to be IF filters, selectivity is not outstanding either (though at least the set should work well with low distortion even in countries with an empty FM band and highly modulated stations). I would recommend an IF filter modification with something like two matched 180 kHz filters (much better already), or perhaps 180 + 150; I have a 110/150 combo and stereo separation is largely gone (plus they do not seem to be matched very well, as weak signals come out pretty distorted).

MW reception

SW reception

Sound quality

A big weakness of this receiver.

Build/Misc.

Bacteria, err, battery life

The 7600G is fairly thrifty on batteries for a PLL set, with current consumption being somewhat less than average (at about 65 mA on shortwave) and not too high a switchoff threshold. You may experience some instability when using synchronous detection at low voltages.

Conclusion

The verdict? Still a nice, well-made travel portable with some unique strengths but also a number of weaknesses. It's nice for listening to some hams, but not quite ideal for broadcast listening, particularly if you're a "band cruiser". I don't use mine a whole lot these days, save for LO het chasing.

Notes

This sample's serial number is 157792, apparently the very last ones in 2001 got a bit past the 300000 mark (I've heard of a 326xxx sample).

The special trick for 160m (tested with a stereo mini-to-mini cable, but a stereo or possibly even mono 3.5mm / 1/8" plug should do):
Tune to a 160m frequency with some activity, e.g. the CW areas. Insert plug into antenna jack and try to find the intermediate (not entirely plugged in) position that results in much higher signal and noise levels – apparently this engages the ferrite rod.
That should already work quite well, but ideally you now have an AM loop of the larger kind that still provides a boost up there (like mine). This should improve reception a good bit further.
It wouldn't have been too bad an idea to use the ferrite rod up to, say, 2.5 MHz instead of switching to the whip at 1711 kHz (which does limit MW intermod up there, but like stated is equally bad for signal levels).
The only downside I could find was a fairly strong internally generated het at about 1822 kHz that apparently couples in via the ferrite rod. Not sure how it's created. Operating the set inside a compact AM loop, I also noticed that noise around this frequency seems to be picked up with the loop over the right-hand side of the receiver. Middle or left is OK.

Audio noise spectra

Some audio noise spectra (recorded shortly after those for the RD1220):

The SW7600G's response in MUSIC looks like the SW7600's in NEWS, albeit with a flatter passband and steeper filter skirts still, and switching to NEWS only attenuates the highs even further! (Admittedly the changed highs response in MUSIC seems to be mainly due to a tighter filter.) No wonder I generally prefer the older model's (less "communications-grade") audio, the tone control has a greater effect as well. Since the new (cheaper) tone control design did not permit switching in a highpass for NEWS, they just slapped in these additional coupling capacitors which are always in the signal path. Or maybe the routing would have become a mess otherwise.

Here's the effect of the tone mod, which removes the additional coupling capacitors:

You can see that audio response is now pretty much flat down to 50 Hz. Also included is a spectrum of SSB with a 2 kHz BFO offset, which would be a typical ham band listening setup for me and, while not quite as selective, is noticeably easier on the ears. Some of these recordings were done over the headphone output, which shows the channel imbalance there (no idea where that comes from, maybe a bad solder joint at the audio amp).

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Siemens RK709 G4

(Sample obtained used, Aug. 2007)

Early/mid '90s analog travel portable with clock/alarm function measuring about 14.5 x 9 x 3.5 cm. Single conversion throughout, receives LW, MW, FM (mono/stereo selectable, AFC) plus 75, 49, 41, 31, 25, 22, 19, 16, 13 meters (with generally decent coverage, even if "The Beeb" on 9410 is just outside the 31m range). Runs on 3 AAs, one of which is for clock operation. Clock display can be lit for a few seconds if radio batteries are installed. Telescopic antenna can be pulled out a bit like with Sony sets to enable operation on back (no stand present). Minimum number of connectors, headphone and DC. LEDs for power, tuning indicator and stereo. Looks and feels quite well-made, just the bandswitch is quite small and could be easier to move. Most probably made by Sangean (model=?), matching the absence of a carrying strap. Price unknown, estimate 100 .. 150 DM.
Note: Do not open up unless absolutely necessary (PITA, 2 clamps on top and bottom each), and when doing so loosen center screw only.

  1. FM performance: Good sensitivity, decent selectivity but seemingly hampered by AFC. Good channel separation, sound a bit loudness-ish but really not bad. Forced mono is possible.
  2. AM performance: Common to all ranges is only mediocre selectivity, with frequent 9/10 kHz hets. Mediumwave sensitivity proved to be disappointing, with some whistles and stuff thrown in, while longwave is surprisingly good in that regard (maybe my set has trouble with MW, contact problems on the bandswitch perhaps); the ferrite rod is 12 cm long.
    Very good shortwave sensitivity (particularly when used with headphones), up to par with the ICF-7601, with dynamic range typical for a single conversion set but still better than the Sony's. Only the ICF-7600A beats them both. AM audio is quite pleasant if there is no interference.
  3. Sound quality: No more than average hiss, fairly good sound over headphones. Speaker seems to be a smallish 50 mm type, and the rear vents are covered by the main PCB, so it's not exactly a bass monster...
  4. Misc: Best used on batteries – LO gets hum (AM) with external DC (and that's a regulated supply, too), probably power filtering is minimal. Lettering on case almost completely worn off on my set, can't be too durable.

This wouldn't be a bad set if AM selectivity were a little better. Too bad.

Some audio noise spectra (recorded shortly after those for the RD1220):

Don't ask me why frequency response differs in the left and right channel. It is, however, perfectly clear why AM selectivity isn't too exciting – the filter looks like a common 2 or 3 element (+ IFT) job with about 6 kHz but unexciting shape factor, and audio filtering is minimal (which effectively means elevated highs in FM).

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Opera PLL 205 (Leetac KA-LT203)

(Sample obtained Aug. 2007)

Cheapie Chinese-made PLL travel portable (apparently a Leetac KA-LT203) that used to be sold by discount chains for about 20 EUR in 2006. Covers LW (1 kHz), MW (9/10 kHz), SW (5.95 .. 15.6 MHz, 5 kHz) and FM (50 kHz steps). About 14.5 x 9 x 3 cm, almost equal in size to the RK709, but with a cheaper feel, of course. Runs on 3 AAs or DC. Headphone jack, antenna jack (certainly not standard in this class and a welcome sight) and attenuator provided. 10 presets per band, direct frequency entry plus extra button for selecting meter bands. Gimmicky LED-based stereo bar volume indicator. Momentary display lighting as long as button pushed, flip-out stand on back, battery lid not hinged. This set got my attention because I spotted a 4-element AM filter (LT455HTU) on an internal photo of what seems to be an internally identical set in a different color scheme sold as "GPX DA8". Another variant is called "JGC RWE-56". Based on the venerable CD8132GP IC. A variation with nearly identical looks but MW / FM / TV / weather (NOAA) coverage (no shortwave or longwave) is sold as Kaito KA2031 in the US.

  1. FM performance: Very wide filter, so-so sensitivity. Sound over headphones is pretty decent.
  2. AM performance: The filter still is on the wide side of things, with an estimated 12 kHz bandwidth, but thankfully it keeps off the dreaded 10 kHz hets pretty well (which was to be hoped!). Sensitivity for the most part is fairly unexciting, bordering on semi-deaf. It picks up a lot on shortwave if you attach an external power supply (or touch the whip during battery operation) but then overloads easily. Connecting the AN-LP1 (mounted at window) results in overloading, maybe a passive tuned loop would work better. Seems like this set could have done with a little more IF gain, say, 10 or even 20 dB. Internal interference only noted on longwave. On mediumwave, my "AM loupe" helps a lot, which was to be expected.
  3. Sound quality: Not bad over headphones, with average hiss levels, the speaker is a 50 mm job and sounds just like that (almost identical to RK709).
  4. Misc: Mutes during tuning. Volume pot turns backwards. Indicator thingway only shows anything at ear-blasting volumes. Lettering under numeric keys and keypad layout are awkward and take some time getting used to. Up/down keys must be pushed pretty hard. Attenuator doesn't do all that much. Uneven display lighting with a single LED, gives audible *thump* in audio and LO signal when activated.

Well, one could buy far worse junk in the bargain basement category. That doesn't mean, however, that this set would have knocked me off my socks. It is sufficiently selective to listen to the big, powerful stations on shortwave (which is about anything it'll get without some help in the antenna department, something that with an antenna input is easier to accomplish than with other cheapies not having one) without annoying 10 kHz hets. With a big tuned AM loop, it might be a decent start into mediumwave DX, and if you're a very skilled person you might be able to squeeze in an IF amp, plus the LO signal seems to be clean enough for decent DRM SNRs on MW (though not too much on an absolute basis when listening to it), but generally I can't really recommend this model. Ultimately it's the lack of IF gain and thus sensitivity and dynamic range that spoils it for me.

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VEF 206

The VEF 206 is a portable transistor radio with longwave, mediumwave and shortwave coverage made by Tento in Latvia (then part of the USSR) from about 1973 to 1989; the 206 was an export-only model. This single conversion receiver (IF 465 kHz) uses analog tuning with the scales going from right to left, and band switching is done with a turret/drum tuner. Shortwave coverage includes 120...75m, 60...41m, 31...25m, 19m, 16m und 13m, longwave stretches to beyond 400 kHz and MW to about 1650. Frequency marks are fairly sparse everywhere.

The set measures 30.5 x 24 x 10.5 cm and weighs 2.7 kg. The case is plastic with a "fake leather" type surface at the sides and top. That also is the weak point of an otherwise very rugged set, as it gets brittle with age, and a drop may cause quite some damage. (A moderately tricky glue job was necessary with my sample.) Other than that, the mechanics are very rugged, even the knobs are made of metal (not so good in case of the volume control, since touching it when using an external power supply will cause a hum).

In terms of semiconductors, the whopping number of 10 transistors and 2 diodes is found inside (but remember it's AM only). Funnily enough, it runs off MINUS 9 V DC, + is grounded. (This seems to be common in other old transistor portables as well, like early-'70s Grundigs.) A DC input jack (center positive) is provided, along with a battery compartment for six D cells (R20). The battery compartment door pretty much cannot get lost, being fixed with screws.

The receiver concept: One tuned RF tank circuit, RF preamp, mixer, 7 tuned IF filter circuits with two IF gain stages, 3 AF gain stages.

Overall, this may not be the DXer's dream set, but for what it is (a relatively humble concept by today's standards), it performs remarkably well. Today's radio designers could learn a lesson about parts selection here. (It, however, also illustrates why resonant circuits should be kept reasonably compact, shielding can't hurt and clean PC board layout comes in handy at times. The limited AGC range is very oldschool as well.)

Some docs including a schematic can be found on this page detailing a DRM mod (certainly a brave endeavour given the frequency stability).

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Redsun RD1220

(Sample obtained slightly used, early 2008, originally bought late 2007)

Intro

I recently (early 2008) managed to obtain an almost new sample of this Chinese shortwave travel portable (the export version with English labels, only the back still shows Chinese text). This is an analog-tuned set with digital frequency readout and clock / alarm functions that measures 16.9 x 10.8 x 3.2 cm and runs on 4 AA cells. MW, FM and shortwave in 9 bands ranging from 75m to 13m are covered. On shortwave, it employs dual conversion, more on that later. Readout accuracy is 1 kHz on the AM bands and 100 kHz on FM.

The RD1220 is positioned against sets like Degen's DE1104 and sits a notch above dual-conversion analogs like DE1107 or Tecsun R9700DX, so it's not quite a "serious" shortwave set yet. However, they didn't skimp on useful and partially unique features – you can disable the AFC for FM, there's an RF gain control for shortwave, an external antenna input for SW and FM and a DX/Local attenuator switch affecting said reception ranges. A 3-step tone control is provided, along with the usual headphone and DC jacks, and a slow charging function for rechargeables (now basically a standard feature in Chinese portables) is also provided.

The set ships in a box with some shaped eggshell carton holding the things inside. Supplied accessories are a power supply (for the Chinese market, so one still needs a mechanical adapter for outlets here in Germany), a nice leatherette carrying pouch (even has a hole for the headphone plug in it), a windup reel antenna (fairly light but solid feeling) and some earduds, err, -buds that I didn't bother to unpack. Apparently some of the usual cheapo 1200 mAh rechargeables are also included, I did not obtain these with my set. I was a bit stumped when I found the carrying strap as a separate item – maybe this had been removed by the previous owner, even though the screws looked untouched.
tquchina (who this set was originally bought from) also includes an 8 cm CD-R with some user manuals on it; the RD1220's is in moderately understandable Chineseglish, and I would recommend trying out the set without looking at it first if you normally get by without one quite well (Real Men[tm] don't read manuals anyway :P).

The current sales price is US$34.99 plus US$23 for shipping. US$24.99 plus shipping will do if you can live without the earbuds and rechargeables, higher-quality counterparts for which you might already own.

Look and feel / Operation

FM reception

Shortwave reception

MW reception

Audio

Power

Misc.

The main board is dated 2006-08-12, so the set was developed at about the same time as the RP2000/2100. Thus it's not too surprising that is has some of the same oddities. As seen on other sets like Degens, the dual-layer board is equipped with surface mount components on one side and through-hole stuff on the other.

Conclusion

So do I like the RD1220? Absolutely. It takes an old concept and breathes new life into it with high flexibility, a superb FM part and a digital frequency display. (It's too bad that MW performance is only average.) As a travel portable for listening to relatively undisturbed shortwave stations in good quality, it gets the job done easily. For mobile usage with headphones, some soldering action will be required.

This reft and light channel mixup on the headphone jack is unfortunate. Things like that do happen once in a while, particularly with a tight schedule as it is frequently the case these days (and the Chinese tend to invest only as much as needed to get things working halfway well, see RP2000/2100 firmware quirks), but something as basic as this should really have been caught in the prototyping stage.

Turns out the RD1220 actually is a keeper. Together with the HD420SL, it is just small enough to be dragged around every day, and that's just what I do did, before actually getting the DE1102. Can't beat having some good music when doing work at the computer. (Note: Matching radio station required. Not provided with set. :P) And when I feel like getting informed, I can tune into DW on 31m or one of the MW locals, with reception quality mainly being limited by an interference-ridden office environment. At home, it meets the criteria for nighttime listening pretty well (reasonably compact, permanent display lighting, stereo headphone out, antenna jack).

These days, the RD1220 has largely been replaced by the DE1102 (mobile FM usage) and E100 (nighttime listening) here and spends most of its time in the assorted radios drawer. That being said, while the RD1220 "barefoot" places behind the E100 (mostly due to its large AM bandwidth), the AN-LP1 / RD1220 combo remains a hot choice for catching those weak 75m/76m stations in good audio quality. (Provided the DW DRM flamethrower is not on air, that is – the Redsun's dynamic range is somewhat limited after all.)

Audio noise spectra

Some audio spectra when receiving noise only:

What we can see is:

  1. Deemphasis is off, about +2.7 dB at 8 kHz and about +3.5 dB at 10 kHz (referring to 1 kHz), rising further as frequency increases. At the same time, 1 kHz is already down 1.5 dB from 100 Hz, effectively giving a boost of the lower frequencies. So there already is a slight loudness built-in.
  2. There is no dedicated internal highpass filtering present, as frequency response remains flat right down to 20 Hz (even below, actually), even in AM. Neat!
  3. There even is a built-in pilot tone filter. It suffers from drawing board syndrome, as the actual center frequency comes out as about 16 kHz instead of 19 kHz (a frequency response measurement in prototype stage would have shown this, but apparently nobody bothered to carry out any), and the Q is not terribly high (plus it starts to influence frequency response at about 10 kHz), but hey, at least they bothered with including one at all.
  4. Do not trust your ears when levels may vary. While MUSIC turns on a loudness-type EQ indeed, NEWS seems to switch in an additional 1st-order lowpass to reduce the higher frequencies when compared to NORM – however, it also is louder than NORM (presumably it uses the same EQ circuit as MUSIC in a different configuration), so I was fooled into thinking that in fact a highs boost is enabled!
    Switching from NORM to NEWS attenuates 5 kHz by about 7 dB and 10 kHz by about 13 dB. This is just audible and not groundbreaking by any means.
  5. The AM filter is fairly wide indeed. Closer inspection of the plots in RMAA yields -6 dB at close to 5 kHz (subtracting the effect of the audio response), meaning a filter bandwidth of about 10 kHz. At 8 kHz, we've gained another 10 dB of suppression, for a total of 16 dB (off-tuning by 3 kHz already gives a fairly decent 5 kHz het suppression). At 10 kHz, filter response only is 33.5 dB down. (And this is with the effect of the AM detector's filtering, which however does not seem to be significant at audio frequencies.) The plateau between 10 and 15 kHz could be some IF-level noise. Further up, the noise floor of a 16-bit recording is limiting things (I had already cranked the volume all the way up but didn't want to change the carefully adjusted recording level).

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Degen DE1102

(Sample obtained new, May 2008. S/N AE044834)

Intro

The Degen DE1102 is a radio I had been intrigued by for a while but never gotten around to actually buying. Well, now in 2008 I have one. It's a very compact portable measuring about 14.3 x 8.8 x 2.85 cm (yet smaller than the RK709 G4 or PLL 205) that covers mediumwave (522 to 1620 kHz in 9/1 kHz or 10/1 kHz steps, I have not tested whether my version will receive up to 1710 kHz with 10 kHz), shortwave (2998 to 29999 kHz on my sample, 5/1 kHz steps) and FM (70 to 108 MHz in this case with 50/10 kHz steps). On the AM ranges, it works with dual conversion (10.7 MHz / 450 kHz). The set can be powered by three AA cells or via a DC input (6 V, center negative), with a charging function for rechargeables.

My DE1102 is a Thieking & Koch sample, obtained for the princely sum of EUR 69 + 5 shipping after the Scott RXP80 variant appears to be no longer available (which even sold for less than 60 but had adapted firmware with e.g. FM coverage starting at 87.5 MHz). That kind of price is OK (remembering that a directly ordered sample cost about 60 when it came out), unlike the 119 EUR that officially imported samples sold for originally.
My readers in the US might know this model as Kaito KA1102, which sells for $79.95 at Universal Radio (as of 05/2008). The Degen "original" can also be ordered from one of the usual well-reputed Chinese dealers.
November 2009 update: It appears that this model has been phased out or at least pushed back by the manufacturer some time this year – offers have thinned out quite a bit. So if you still want one, better hurry up.

The DE1102 may be small in size, but it's not light on the feature side: Antenna input, switched attenuator (SW and FM only), two AM filter bandwidths, SSB with fine tuning (previously unheard of at this kind of receiver size and price) and a tone switch are present. A total of 190 memories on 10 pages are provided (an auto-memorizing function = ATS is also available), and a total of four LEDs serve as a signal strength display, with one of them being relegated to function as a stereo indicator on FM. Speaking of FM, you can choose between mono and stereo reception (when using headphones, the 2.5" speaker is mono) and enable a bass boost there.

Supplied accessories include a power supply (with the right kind of mains connector in this case), stereo earbuds with pads (which enjoy a good reputation regarding sound quality), and, underneath the plastic inlay holding the radio and the parts just mentioned, a velvety drawstring carrying bag, a wire antenna with a mono 3.5 mm plug, three NiMH rechargeables with an official 1300 mAh and, of course, the manual. The latter is in German only in this case, quite well written and even includes a few tricks not found in the original English language manual; it was authored by MicroConsult GmbH (my German readers may know eBay seller "wittsfeld"). This cooperation explains the "Thieking & Koch" brand, I guess.

Look and feel

Operation

Audio quality

FM reception

Shortwave reception

MW reception

Daytime MW sensitivity is close to e.g. the ICF-SW30 over much of the band, however there's some display/microprocessor related ticking/buzzing to be heard on empty channels as well as weaker stations. Sensitivity noticeably drops at the upper end of the band, making the DE1102 fall slightly behind the reference set. (At least the ticking disappears as well.) The RD1220 is about the same in raw sensitivity (and ferrite rod size) but seems to have less gain.

The restricted lows in the DE1102 reduce subjective sensitivity, even more so during speaker playback – the venerable Sony ICF-7600A, a design that's more than 20 years older but features better raw sensitivity (larger ferrite rod in a generally larger set) as well as carefully tuned speaker audio, beats it hands down.

All in all, a decent but unexciting showing, with the internally generated interference degrading sensitivity somewhat.

Battery life

Misc.

Cellphone interference has not been a problem so far. It apparently takes pretty high levels for it to be audible at all, which so far hasn't happened more than once or so. The DE1102 is much less critical than e.g. my vintage Toshiba pocket radios in this regard.

Audio noise spectra

Now for the usual audio spectra:

Conclusion

Overall, the DE1102 is a compact, fairly affordable portable that, while far from flawless, shows pretty respectable performance for this type of set. It does best on FM and the lower shortwave ranges. I wouldn't mind if some of the bugs (mainly shielding-related stuff and SSB warble) were worked out, but even as-is, it has much to recommend it. And it's cute. What more do you want? :p

Due to the qualities of the headphone out and FM section, the DE1102 has replaced the Toshiba RP2059 as mobile FM radio together with Shure SE420s (and UE attenuator).Yes, it might be a touch oversized for the kind of application, but do you know any pocket-sized FM radios with good selectivity, sensitivity and dynamic range plus a hiss-free headphone out?

Notes

After not even one year, my DE1102 developed a defect: It became fairly deaf in the narrow AM bandwidth. Interestingly enough, the problem disappeared again soon after and has yet to resurface after more than half a year. (It did eventually when taking out the batteries, but putting them back in cured this again.) Knowing the qualities of the cheapest kind of lead-free solder (namely, being prone to developing bad solder joints), I suspect a bad solder joint. I wanted to have the set modified at some point anyway, but still something like this doesn't exactly speak for quality.

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Grundig Concert-Boy 1100

The Concert-Boy 1100 is a large domestic portable (about 40 x 22 x 9 cm in size and more than 3 kg in weight, with a detachable carring handle) dating to the mid-1970s; it saw a 5-year production run from 1973 onwards and apparently was one of the first sets for the German domestic market made in Grundig's factory in Braga, Portugal which had opened in 1965 (this one still exists to this day, now manufacturing aftermarket and OEM car radios as Delphi Grundig). In its day, it was above average but by no means a top-flight portable like a Satellit. In those days, the market for more upscale portables was already shrinking, and Grundig had gone public, so first signs of cost-cutting become apparent. In return, development focused on service friendliness – this set, for example, can be opened after removing only two screws at the bottom. Ironically, Grundigs of this period usually hold up well.

Band coverage includes longwave 145 to 280 kHz, mediumwave 510 to 1620 kHz, spread 49m band 5.9 to 6.23 MHz, rest of shortwave 6.1 to 18.5 MHz and FM 87.5 to 108 MHz. It is single conversion throughout, with IFs of 10.7 MHz on FM and 460 kHz for the AM ranges. A total of 10 tuned circuits for FM (2x frontend, 6x IF filter, 2x ratio det) and 7 tuned circuits for AM (2x frontend, 5x IF filter) find use, plus there's a 5 kHz audio notch filter to improve effective AM selectivity on shortwave in particular, and AFC is employed on FM. There are 3 FM and 2 AM IF gain stages. Semiconductors include 13 transistors and 10 diodes. There is a 0..100 logging scale on the inside of the dial window (an awkward place given the amount of parallax distortion, which is far greater than for the dual-bar pointer on the main dial).

This set can be powered by either 6 D cells or mains, where it isn't picky and will run from 110..240 V without adjustment. Like any better portable of its day, it provides a tape I/O via a 5-pin DIN jack. A symmetric 240/300 ohm FM antenna connector is also present. Tone adjustment is possible with separate bass and treble controls. The speaker is a large 7" by 5" (approx. 18 by 13 cm) wideband type, rated output power is 2W sine.

The telescopic antenna measures about 78 cm when extended. It can be fixed in six different angles horizontally (i.e. 60 each) and three vertically (i.e. 45 each) and disappears inside the set when entirely collapsed.

Available finishes were black and wood imitation, my set is of the black variety.

My sample had obviously been through some hard times, as it arrived miserably dirty inside and out and with signs of heavy use, like a junkyard special. Extensive cleaning was required, including a polish of the dial window. Functionally it did better, with only the highs control being non-functional (which was later found to be caused by the pot's wiper having come off and floating around inside, no idea how this happened or how to reattach) and the switch array causing some intermittence (tuner cleaner improved things). None of the bands were way off, only the very widely spread 49m band had an immediately visible deviation (DW on 6075 made an appearance at about 6.11 MHz, i.e. 35 kHz high – still peanuts, absolutely speaking). This speaks for good alignment stability.

Overall, this is a classic domestic portable that excels at good, stable reception of somewhat less critical stations with great sound. As the saying goes, they don't make 'em like they used to...

There are a few problems that I've been wrestling with:

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Eton / Lextronix E100

(Sample obtained used, mid-2008, originally bought new Mar 2008. S/N: E10-0709032118)

Intro

The E100 is a small PLL synthesized shortwave portable that covers MW (520 .. 1710 kHz in 10 kHz steps or 522 .. 1620 kHz in 9 khz steps, fine tuning in 1 kHz steps), SW (1711 .. 29999 kHz in 1 or 5 kHz steps) and FM stereo (either 87 .. 108 or 76 .. 108 MHz in 100/50 kHz steps); FM coverage and MW steps can be selected by the user. It measures about 125 x 76 x 31 mm, which means that it is only a touch larger than the Philips AE3405, noticeably larger than the DE105 and a good bit smaller still than the (already cute) DE1102. Weight is specified as 198 grams (I haven't dragged out the kitchen scale to confirm this, but would assume it's without batteries, which typically add about 25..30 grams each). Power supply is via two AA cells, either primary cells or rechargeables are accepted (with the user being able to select the type for correct battery meter display).

The set has a numeric keypad for direct frequency entry, keypad or rotary tuning, a 3-step input attenuator, a high/low tone switch, a locking slider and selectable mono or stereo operation on FM. A total of 200 (non-volatile) presets are provided that are spread over either 4, 5, 8 or 20 pages depending on setup, and there are clock and alarm functions as well. Connectors include DC and headphone, that's it – there was no space left for an antenna jack, unfortunately.

Accessories supplied include a user manual (in a number of languages but not incredibly detailed, and no specs as usual for the company, there only are a few on the packaging), list of European distributors, carrying pouch and apparently some earduds, err, -buds as well, which I did not receive with my set which was (very lightly) used. (It's not like I'd miss them.)

Typical new prices here in Germany have traditionally been around 80 EUR (plus shipping), but more recently some stores dropped this to about 60 EUR, less than you'd pay for a (more full-featured) DE1102. That seems like fairly reasonable pricing now. (Update May 2011: All sold out.) In the US, you can expect to pay more than for a KA1102 and about as much as for a G6 Aviator if you buy the "Grundig" version G100. Canadians are more lucky than that, they can obtain an E100 (the "old" model, not the one I review here, more on that later) for little more than $50CAD.

Versions

As we all know, the E100 is (/was) made by Chinese manufacturer Tecsun. It originated as a slightly modified version of Tecsun's PL200 with a curved front and rubberized surface (which feels nice but has been reported to be subject to wear). This was a single conversion set throughout with an AM IF of 455 kHz.
While there had been some internal changes to past models, like the change of the ferrite rod antenna to an adjustable type that gave better MW performance (in parallel to the PL350, it seems), "ultralight" MW DXers (see dxer.ca, "ultralightdx" Yahoo! group) were shocked to find that new samples of the E100 (serial numbers 0709xxxx) are entirely different inside. It is now a dual conversion design with a high 1st IF of 55.845 MHz and a 2nd IF of 455 kHz (confirmed by the set of spurs encountered). This also means that the MW frontend now is a broadband type, rather a step back for MW DXers as this generally is more prone to overload. It is to be assumed that the current version is more related to the PL450, which came out in early 2008. My sample was originally bought in March 2008, so the revamp must date back to early 2008 at least. A little creative interpretation of the serial number suggests a September 2007 build date. As this model was discontinued in mid-2008, this may actually have been the last batch.

Look and feel

Operation

FM reception

Good above average portable level reception, but not that spectacular either. Tecsuns usually have to make do with only one ceramic IF filter, and that shows in less steep filter skirts when compared to e.g. DE1102 and RD1220. It still manages to pull some stations that give sets with 280 kHz barn doors trouble, and stereo separation seems good, but an FM DX king it is not, and audio distortion could be a touch lower as well (seems like the filter peaks about 50 kHz high, or maybe the tuned IFT is not aligned correctly). I've seen more sensitive sets, but in return it overloads less easily than e.g. the DE1102.

Shortwave reception

MW reception

Audio quality

Battery life

This set appears to be quite economic. After more than three months of irregular use (frequently with display backlighting on) on the same set of Eneloops, discharging still yielded almost one third the nominal capacity.

Misc.

Actual tuned frequency in the AM ranges appears to be about half a kHz high on my sample. I was under the impression that this varied a bit, so suspected that some tuning resolution was generated by offsetting the 2nd LO if needed (see ICF-SW7600). However, some LO chasing with the DE1102 revealed this not to be the case – the 1st LO changes frequency on every 1 kHz tuning step on shortwave.
Mediumwave, however, seems to be different – here the 1 kHz steps are obviously not all created equal, and I noticed larger offsets of effective tuned frequency (up to 1.5 kHz) on my set. More specifically, stations on channels with even frequencies (e.g. the classic BBC WS frequency of 648 kHz, R.I.P.) come in best when tuned 1..2 kHz higher, as opposed to 0..1 kHz for odd frequencies. That does smell like the 2nd LO tuning trick at work here with a 1st LO resolution of 2 kHz (meaning that the 1st IF is odd like 55.845 MHz – odd IF + odd tuned frequency = even LO frequency), with imperfect alignment accounting for the intermediate steps not being right in the middle. Still, why would this be required on MW if it isn't on SW? Unfortunately I can't confirm it directly, not having a receiver for approx. 56 MHz.

Conclusion

Overall, the current E100 is a well-performing little set that would serve the world traveller well for catching broadcasts on the AM ranges. (One would only wish that it tuned longwave as well, which now should be possible, though it's unclear how well that would work given the track record of the ferrite rods used on these Chinese sets.) For something that doesn't receive all that much attention, it does a pretty respectable job. While not flawless, it is both smaller and less expensive (at a typical 79€, or even 59€ nowadays) than e.g. the venerable Sangean ATS-606A, though it does lack an external antenna input (and I would guess that the Sangean's 2nd mixer shows better nearby IMD performance).

Its closest current competitor is probably the Grundig G6 "Aviator" from the same stable (though presumably Degen OEM'd), which at much the same dimensions features knob tuning, SSB reception and even air band reception. (G6 inside pics. Yep, it says "ETON E6" on the 'board!) From what one reads, this one behaves similarly to the DE1102, and the (typical Degen) somewhat more complex operation and (typical Eton) not so detailed manual don't make such a good combination. The E100 may be much less flashy, but it certainly is more predictable. Plus it's easily available here in ol' Europe, which still isn't the case for the G6 (the rights for the Grundig brand only apply for North America).

In the meantime Tecsun has also released a model PL-210, which presumably uses the same or very similar receiving electronics as the current E100 but updates the user interface side of things, including more memory presets than you'll ever need and longwave reception. This is nice to see, as it should benefit from the improved operation of their other modern-day models (which generally receive praise in the user interface department). So far you can only buy a PL-210 directly from China.

Notes

In North America, there also is a "Grundig" variant of the E100, the G100, which is identical save for being black. Universal Radio only sell this one now.

It be noted that QC has been reported to be a little hit and miss.

S/N: E10-0709032118

I would speculate that the first four digits of the serial number (0709) stand for either internal hardware revision, batch number or production date (which would mean September 2007 in this case), while the digits that follow are the actual (ongoing) serial number. A little over 32000 samples isn't too much for a radio like that. Serial number ranges that have been spotted are 0505, 0609, 0704 and 0709, with the first three appearing to be "old" samples (with some smaller differences, e.g. early ones don't have an adjustable MW antenna coil) and the last one "new" ones.

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Sanyo Eneloop rechargeables

For someone who likes to use his portables on batteries yet would not like to waste a bunch of primary cells, rechargeables are the power source of choice.

Now conventional NiMH types have a number of drawbacks, one of the biggest ones certainly being high self-discharge rates (even more so in current high-capacity cells than in those with about 2000 mAh or less). If you have a drawer full of radios that may not be used for some time, you can bet that by the time you want to use a particular one, its cells will be almost flat yet again. That doesn't get any better with age, and if you've got some damaged cells in there, it's even more fun. (Again, the very high-capacity stuff has proven quite unreliable, being easily damaged by overcharging. Out of two sets of four 2500 mAh Sanyo cells for camera use, always charged in a "good" charger not known for blatant overcharging as long as the cells were halfway low resistance, a total of three cells showed excessive discharging indicative of internal leakage. Sure enough, the camera always complained about empty batteries pretty soon whenever it was used.) A good occupational therapy. Conventional NiMHs should be called "chargeables", since that's what you end up doing most of the time…

To the rescue came Sanyo's Eneloop cells, the first exponents of the new crop of NiMH+ / "low self discharge" / "ready to use" cells. First introduced in Japan late 2005, they slowly became available worldwide the next year. Nominal capacities include 2000 mAh in AA (R6) and 800 mAh in AAA (R3) size, with C and D sizes being covered by mechanical adapters (C and D sized cells with minimum capacities of 3000 and 5700 mAh and PTC-based short-circuit protection were eventually announced in 2008, suspected to contain three AAA or AA cells each, respectively). While capacities were somewhat smaller than what was available in conventional NiMH cells, they soon built a reputation for low self-discharging, low internal resistance (with decent performance even at low temperatures – the product launch "down under" was staged in an ice bar, now how cool (literally) is that?) and excellent matching that made creating hand-matched sets of cells redundant. There have also been very few reports of failures (which is to say that I haven't been able to find any, just statements of very low failure rates).

Pricing of Eneloops is about 10 EUR for a set of four AA or AAA cells.

Competing cells, marketed under quite a number of brands but only manufactured by a handful of OEMs, typically have a specified capacity of 2100 mAh in AA size and somewhat worse properties otherwise. They do not all appear to be as rugged as the Sanyo cells.

Currently I have several sets of Eneloops in use, mostly AA (plus 4 pieces AAA), first bought for my camera (a somewhat picky beast) and then displacing more and more of the conventional NiMH cells in my radios (currently none of the 2500 mAh Sanyos are in use and all of the crappy old 2200 mAh noname cells have gone to recycling, but some 1850 mAh Sanyos bought as NOS remain). Do they live up to their reputation?

In a word, yes. While they will eventually lose some voltage when sitting around for a while (but then still give off plenty of charge even at untypically low levels) and I guess internal resistance will creep up as in conventional NiMHs, self-discharging is much reduced, and so is the number of extra charging cycles – actually, I don't think I've recharged any of them for anything but "real" current drain from the devices they were used in. In both my little Olympus (2x AA) and my dad's Fuji (4x AA), they keep on going and going. During charging at 700 mA, they do not get overly warm, and end-of-charge detection works reliably (the charger has a habit of failing to do this given cells with high internal resistance). Voltages and capacities stray very little between cells, to the point that they may be within a mV even after some time. Accidental deep discharging happened once or twice so far, from which the cells seem to have recovered well. Failures? None so far.

The verdict? Eneloops have definitely made life with rechargeables a lot easier. They go a long way towards closing the gap between conventional NiMHs and the user-friendliness of lithium based cells. You still need a decent charger for them and deep discharging should be avoided as much as for other NiMH cells, but other than that they're pretty much bulletproof. Recommended? You bet!

Postscript: By now, you can also obtain higher-capacity "XX powered by Eneloop" cells with 2500 mAh (HR-3UWX, vs. HR-3UTG for the "classic" Eneloops or HR-3UTGA for the 2nd-generation ones). These are mainly geared towards digital cameras and such, with the expected results of thinner membranes: Higher self-discharge rates, less cycles, less robustness. Inner resistance still seems fine though. I think us radio nuts are better off sticking with the standard types, which are cheaper to boot (plus you can also buy them in flashy colors if you're so inclined).

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Sony ICF-2001D

In Feb 2009, Helmut G. Vogel generously lent me his early production ICF-2001D, S/N 30809 (mid/late 1985 or thereabouts), for evaluation purposes.

Intro

How does one review a receiver legend? Well, let's start with the basics: This model (along with its North American counterpart ICF-2010), first available early 1985, was Sony's top shortwave portable and the first ever consumer-level set to feature synchronous AM detection. While the ICF-2001D was discontinued when the ICF-SW77 arrived in about 1991/1992, the '2010 remained available until 2003 at a typical US$379 (MSRP US$449). An 18 year production run may well be a record for consumer electronics. (Only the ICF-EX5, a Japan market set, still beats that – also introduced in 1985, it didn't begin to disappear from store shelves until early 2009, only to be replaced by an updated "Mk2" model later that year.)

What we're looking at is a lap-size portable measuring an official 28.8 x 15.9 x 5.2 cm (a longish shape) and weighing about 1.8 kg including batteries – which would be three D cells (main) and two AA cells (backup). There is a slide-out telescopic antenna which measures an impressive 120 cm in length while still making a fairly robust impression. A magnetically retained (!) flip stand allows for a low angled position on the desk. A shoulder strap for carrying the set can be attached and was originally supplied.

Tuning ranges vary depending on version. There is an AM range potentially extending from 150 kHz to 29999.9 kHz (but limited to 26100 kHz in e.g. German version) covered in 1 kHz or 100 Hz tuning steps, the FM band is covered from 76 MHz (or 87.5 MHz) to 108 MHz in 50 kHz steps, and there may be an aeronautical (air) band ranging from 116 to 136 MHz, tuned in 25 kHz steps.

For cruising the waves, you get a number of tuning options: First there is a tuning knob at the side, with two user-selectable step sizes and thus speeds on the AM ranges. Then there is a numeric keypad for direct frequency entry. Finally you get no less than 32 individual buttons for presets, which double for things like direct broadcast band selection.

On the AM ranges, you have the choice among several modes: Wide and narrow IF bandwidths can be selected, synchronous detection toggled on and off, and finally you can also set up the receiver to tune in SSB transmissions in either the upper or the lower sideband.

There is a two-part LC display with a clock / timer and a frequency section. Frequencies are shown to 100 Hz on the AM ranges and to 1 kHz elsewhere.

Antennas for both AM and FM(/AIR) ranges can be connected (3.5 mm jacks), as well as a power supply and headphones (mono). A (mic-level) line-out is also provided. The set was supplied with an antenna adapter that takes coax.

The main opponent in reception will be the venerable ICF-SW7600, freshly recapped by aforementioned gentleman (his third "patient" in a row, all with the caps measurably dried out and with PCB corrosion on one sample). Two fairly full backup AAs and three 4000 mAh D size NiCads (also rather full) were installed in the 2001D.

Operation

Shortwave reception

MW/LW reception

FM reception

While the set does appear to be decently sensitive, selectivity with the two stock 280 kHz filters (barn doors) is hardly to be called exciting. Some modern-day low-loss 180s or 150s would work wonders here.

Air band reception

In terms of real signals, I caught one (1) volmet station. I could hardly conceal my excitement. Seems like this is not a terribly interesting region in terms of air band. There were only a few spurs and mixing products, but then FM band signal levels aren't exceptionally high here either.

Sound

Speaker audio, while frequently criticized, is perfectly fine for the speaker size (looks like a 10 cm / 4" job and consequently outclasses my sets with smaller speakers). Nice balanced portable audio, maybe not breathtaking but perfectly adequate on FM. Even on the AM ranges where the low end is noticeably reduced, it still manages to sound somewhat more "grown up" than the ICF-SW7600 overall, although the difference is smaller.
There is some handwritten data on a label on the back of the speaker driver, including a resonant frequency of 175 Hz, impedance of 4.2 ohms and a 1984 build date.

Hiss levels on headphones are average, maybe a touch more than on the ICF-SW7600 if only one channel is used, but lower if it's split to supply both drivers.

Quirks

There are a number of documented quirks on this set. One is the battery-to-circuit-board contacts for both sets of batteries (solder pads which contacts press against, aided by the back case), which if subpar may cause "Error 3" messages or loss of time and memory contents. The backup batteries do not sit terribly firm either. While there is a main supply voltage line that goes to the control PCB for display lighting, this was not used for implementing a "backup backup" supply, i.e. supply of the control circuits from the main batteries if backup supply is out. This is all the more surprising considering that the older ICF-7600D/2002 has it.

Many of these sets suffer from reduced sensitivity on the shortwave bands due to a blown Q303 (2SK152-1) FET. Protection diodes are effective for the telescopic antenna but not the external antenna input!

Conclusion

Overall, in spite of several idiosyncrasies, this is a fairly decent upperclass portable. With some better IF filters and a tunable antenna (I'd also suggest an audio mod for some more bass in the wide AM mode at least), it's likely to be good for some fun on the short waves. It improves upon lesser sets not so much in terms of pure reception capability but rather reliability (image rejection, frequency readout and tuning steps) and flexibility (e.g. bandwidth selection). A notable exception is the synch detector which does improve reception even on weak signals. Overall, it's no surprise that the '2001D turned out to be a popular platform for modifications – good basic substance with a few quirks.

Would this be the ideal receiver for me? Well, it's a little clunky, and I don't have a charger for D cells (and still no mono adapter for headphones either, believe that?). A number of people use it as a nightstand radio, and indeed it seems to be well-suited for such semi-stationary use.

Notes

There is a host of information on these sets available on the web. Just a few helpful links:

Apparently late-production ICF-2010s (post-1998 or thereabouts) are equipped with AM IF filters sourced in China which show less good quality than the previously-used Murata filters and may exhibit asymmetry in particular (see icf2010 group message 2779).

Alignment notes

First off, unless you're exactly sure you know what you're doing and very careful to boot (it seems very easy to damage the ferrite antenna wires), better leave alignment to an expert!

The sync / SSB alignment procedure as outlined in the service manual aims to accomplish the following:

Carried out like this, there is no way to accomodate non-centered IF filters. You can tweak VT1 afterwards for a symmetrical response in SSB, but then displayed frequency will be off and there will be no change in synch mode. Alternatively you could choose main tuning frequency a few steps higher or lower than nominal at the beginning until you get a symmetrical response in USB and LSB, but then this display offset will be present all the time. (On more advanced receivers like the venerable AOR AR7030, the displayed frequency is corrected by the offset required.)

If you notice a slight frequency shift towards the higher shortwave bands (i.e. you had things adjusted to zero beat on MW/LW yet there is an audible offset up there), a tweak of the 6.275 MHz PLL reference xtal is needed (CT4). Try adjusting CT4 for zero beat on the highest-frequency (reliable) shortwave broadcast or time signal station you find (taking into account the previously found frequency offset, of course), then check back at MW/LW. Chances are there will be a slight offset down there now. Using CT4, aim for the same offset on both frequencies (best stored in presets), then zero beat again via CT601.

I had been wondering why they chose to make the 2nd LO frequency non-adjustable. The answer is quite simple: It doesn't matter! Not within a few kHz at least. This is because it is also used for pre-mixing in the PLL for the 1st LO. If it's off, the 1st LO will be off by the same amount. This merely shifts the effective 1st IF, which doesn't matter much because the filtering up there is relatively wide (15 kHz or thereabouts) and thus quite tolerant. This approach also reduces frequency errors introduced by the PLL reference oscillator being off. At the same time, it introduces the aforementioned problem of not being able to cater for off-center IF filters as easily.

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Tecsun AN-200 AM (MW) loop

Intro

Santa was a little early in bringing me this compact tunable AM loop just before Christmas 2009... I had actually ordered it together with the 2010 edition of Sender & Frequenzen but it turned out to be backordered. It would seem that others were equally aware of effectively 19€ being a good deal. Normally you can also pay twice that.

What you will get when ordering the AN-200 is the compact tunable AM loop itself, an instruction sheet in reasonable-quality English (which claims it's a MW/LW antenna) and a 1/8" male to male stereo cable that can be used to connect the antenna's pickup winding to a receiver's antenna input.

Performance and handling

(Those wondering how I got the ICF-SW7600G to receive 160 meters with the ferrite rod please be referred to the review. A DE1103 / E5 would do this out of the box.)

Look and feel

Externally the AN-200 is quite attractive and equally decorates your desk when not in use. It is also fairly well-made. The tuning knob is reasonably sized ( ~3 cm, ~1.8 cm height), doesn't wobble and turns smoothly. Judging from the feel and tuning behavior, it controls a varicap of the plastic variety. Do not ask me how to disassemble the antenna – I'd guess the two halves of the plastic foot are clipped together, as there are no screws visible anywhere.

Conclusion

/me likes! The AN-200 works well, looks nice (a distinct advantage of a commercially made product) and doesn't give the impression of falling apart tomorrow, all this while not costing an arm and a leg. Thumbs up.

So far, the antenna has held up well, even with a bit of rough handling. Amazon reviews indicate that people have received the occasional dud though, in which case it's best sent back. A good one definitely is a keeper.

Note: A small 9" dia. loop with 25 windings occupying about 1" has about 250 H of inductance (going by the Bob's Tesla Web Lab formula), giving an XL of about 800 Ω to 2.7 kΩ across the MW band. Since my sample will tune up to pretty much exactly 2 MHz, that means minimum capacitance (including inter-winding) is about 25 pF, down from a maximum of about 400 pF. Not a bad little tuning cap there, and wire routing seems quite solid, too.
I probably don't need to mention that near the upper end of its tuning range, the antenna is rather touchy in the literal sense – approaching the windings with your fingers (thereby increasing inter-winding capacitance) throws off tuning considerably. (So far, none of these loops has been caught singing Polly Scattergood's "Please don't touch", but you never know, HI.)

Here's something for you if you feel like simulating inductive coupling operation in LTspice. This was based on what I saw with an AN-200 / ICF-SW7600G combo. Coupling factors K1 and K3 may not be 100% accurate but should be in the right ballpark.

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Homebrew lower shortwave loop

(Rebuild of homebrew AM loop, Nov 2010.)

Intro

My homebrew AM loop recently mutated into an antenna for the higher MW and lower shortwave bands. It gained a proper stand using a piece of big heavy beam and lost 5 turns and 250 pF in the process, was rotated by 45 degrees, now has strain relief measures on both ends of the windings, and the tuning capacitor was relocated to a spot much closer to a corner, thus remedying several problems that plagued the original first-try design (which liked to tip over, had way too much coupling to ground when standing on the floor and wasn't too exciting in terms of wire tension; it also made use of one ground wiper and had excessive high-impedance lead lengths as the capacitor was located in the center). What remains is 4 turns of 4 mm insulated braided wire spaced at 2 cm on a square frame of about 93 x 93 cm standing on a corner, with two 500 pF sections on a split stator capacitor in series.

The tuning range now extends from about 1450 to a little above 4800 kHz, a bit lower than I would have liked. However, going to three turns would have shifted things upwards too much according to several calculation aids. As-is, wire length is between approximately λ/14 and λ/4.

A first pickup loop using the same wire (with a twisted section going from the loop to the receiver) also was added, though the excessive wire thickness makes handling cumbersome. Due to high impedance at this point and modest wire lengths, pickup loop conductivity is not nearly as critical, so thinner wire can be used with no problem and I'm likely to revise this point. The pickup loop is triangular here, about 1/3 loop diagonal wide and 1/2 diagonal long, extending between the corner opposite the tuning capacitor and a center beam. Its symmetry follows the rest of the loop. With a coverage of about 1/4 to 1/5 of loop area, loop impedance is transformed to a value that's still well in the kΩ range. It ought to be much smaller for a 50 Ω input (with tighter coupling, too), but a high-impedance input will do fine here.

Finding the best spot for a coupling loop is easy: it should be where touching a loop winding throws off tuning the least. (After all, we don't want to degrade performance due to capacitive coupling.) This turns out to be exactly opposite the tuning capacitor, at the center of the windings. Not too surprising, as the high impedance point is at the tuning capacitor (also allowing whip antenna coupling there) and the low impedance point should be on the other side.

I later added another, smaller coupling loop using thinner, more flexible wire, again in triangular shape. Its base of about 27 cm runs right next to one of the middle wires opposite the variable capacitor for optimum coupling (so right in the low-impedance region where current is maximum), its sides are about 20 and 24 cm respectively, and again the remainder of the wire is twisted and led to the receiver. This seems to come much closer to a 50 Ω impedance.

Evaluation

The whole affair is undoubtably rather big (about 1.30 m wide and 1.35 m high), a little heavy and thus somewhat cumbersome to handle. While you can place a little 9" loop like the AN-200 just about anywhere, such a big loop has to sit somewhere on the floor where there is enough space for it, rather than in the spot with best reception.

Inductive coupling yields big signal levels as before, well into the noise floor. (I can still make portables break into sweat on MW.) Peaking is fairly sharp, so that reduction drive on the tuning cap and big knob (Al-over-plastic volume knob from a defective late-'70s audio amplifier, basic model but nice build) comes in handy. Q seems to be around 100 on 160m, rather low for that kind of wire gauge, but possibly explained by insulation-related loss.

Directionality is there but, seemingly typical for loops, is most pronounced when signal sources are located about on the same level (which makes sense if you consider its approximately toroidal pickup pattern, same as for a dipole). As expected for an antenna relatively close to ground (I don't have a mast and rotor here...), signals with higher incident angles are preferred. Nearfield directivity appears to vary with frequency.

The connection from pickup loop to receiver is normally carried out as a coaxial cable for good reason: The signal difference between "both legs connected" (differential mode) and "ground connection removed" (common mode) turned out to be only about 12 dB with the "twisted-pair" cable on the big pickup loop. It's not a big deal, since the signal picked up from the loop easily dominates any feedline signal pickup and the feedline is only about 2 meters long anyway, but should be kept in mind for longer connections.

Loop self-resonance (?) seems to occur at about 11.7 MHz when using the big coupling loop. With the small coupling loop, this second peak shifts to about 13 MHz.

The small pickup loop seems to come much closer to a 50 Ω impedance. On 160m, there is no difference in signal level whether or not a FET source follower is used in front of a 50 Ω input (but noise is lower without it), while by 80m the difference has risen to about 6 dB more when using the source follower. A medium-impedance input (nominal 600 Ω) cannot keep up with either. All of this indicates a source impedance that is very low at the low end of the tuning range and then rises to about 50 Ω and a little beyond towards the high end. Indeed, an impedance variation about as large as frequency variation is to be expected when using this coupling method. I may still try a gamma match or somesuch, even though for receive-only purposes it's plenty sufficient as-is, given that received background noise is much higher than receiver noise when the antenna is tuned properly.
The FET-dominated noise floor in the low-impedance region does not come unexpected either, as their higher voltage noise compared to bipolar transistors means that noise figure will be worse at very low source impedances. (The J310 used in this case is by no means particularly noisy for a FET, but its 6 nV/√(Hz) voltage noise level is equivalent to a 2.2 kOhm resistor's. With a low source impedance, that's enough to be detected over the noise floor of a 50 Ω receiver with a ~12 dB noise figure, which amounts to 1.7 nV/√(Hz) or 3.4 nV/√(Hz) EMF. Since the FET has a high input impedance on the lower frequencies, the latter is better suited for comparison.)

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AOR AR7030 PLUS

(Sample obtained new, 2002.)

Intro

The AR7030, here in the "Plus" version, is a communications receiver that covers 0 .. 32 MHz continuously in minimum tuning steps of about 2.5 Hz. It is a dual conversion design with IFs of 45 MHz and 455 kHz.

Sony AN-LP1 shortwave loop: Servicing notes

The AN-LP1 is an active loop antenna for approx. the 75m through 13m range, once designed to work with Sony's mid-90s shortwave portables – notably ICF-SW7600G and GR, ICF-SW100 and ICF-SW1000T. Several other portables are also able to use it, minus the automatic turn-on feature which is only available on the aforementioned sets. I reviewed it many moons ago, with the result admittedly suffering from being badly structured, as all my early reviews were – but there you have it.

Now my unit wasn't entirely perfect, even when not taking the mods performed by the previous owner into account: Unrolling the wire to the antenna frame gave quite a bit of scratching noises during reception, the bandswitch could make somewhat better contact as well, and the peaking on some reception ranges seemed noticeably off.

So after managing to get off a sticker that the previous owner had placed on the back last night (which obstructed one screw), I took my AN-LP1's control unit apart today (2011-05-15). It's not too hard if you're reasonably handy and have the service docs at hand, mostly the usual stuff like making sure small screws don't grow legs and such. A Phillips 0 sized screwdriver is fine.

Reinstalling the takeup reel is a bit fussy as the cable needs to be threaded back in, which is a little annoying as you may have to do that a few times. Reinstalling the screws in the battery compartment is another minor hurdle, you may want to hold the unit upside down or use a magnetic screwdriver (my small ones aren't).

Alignment of the teeny tiny trim pots is reasonably easy with a very small flat-head precision screwdriver. The main problem is that the front cabinet needs to be off, so you'll need to find some other way to turn the miniature surface-mount rotary switch that changes bands. (I found that a somewhat larger flat-head screwdriver did a good-enough job.) I recommend turning the band selector on the front at the same time, so that things will still line up at the end.

Instead of a SSG, I used plain ol' background noise, with the takeup reel put back in its usual place and the loop connected. Works well enough. The receiver used was my trusty '97 ICF-SW7600G.

Following the alignment procedure, I found that a number of the bands were quite a bit off on my sample. Not sure whether this is due to aging or it came like that from the factory. I don't think the control unit had ever been opened before. A few bands were reasonably close, but those were a minority. The only range I didn't touch was 5 MHz, which I'd always found to work great.

I mostly used the specified alignment frequencies, with only a few exceptions:

I took some time cleaning the takeup reel contacts and wiping down the corresponding contact surfaces on the PCB with my usual sealing contact cleaner (Teslanol t6 "Oszillin", about the equivalent of the usual, least aggressive type of DeOxit, I guess). If that doesn't do it in the long run, I may try the kind of contact grease used on car batteries. (The original grease is some greenish stuff.) Sure seems a good bit less scratchy for now.

The bandswitch was another candidate that could make somewhat better contact. After I couldn't find any holes in this thin, surface-mounted thing, I didn't feel much like opening it up. Apparently you could remove the metal cover (certainly so after desoldering), but I wasn't too keen on having miniature switch internals flying about or potentially not getting things back together. Know your limits.

Now for final performance evalution in the markedly improved propagation conditions of May 2011 (really no comparison to last winter):
The realigned AN-LP1 manages to get background noise above the ICF-SW7600G's internal noise floor pretty much all the way from 3.5 MHz to about 25 MHz. (That 20 MHz range has picked up nicely.) The only really weak spot with sub-whip levels is in the 8.5 MHz vicinity, but that was to be expected with the 7 and 10 MHz bands being as far apart as they are.
Using the 14 MHz range on 20m somewhat reduces the levels of 2nd IF images from 19m on the ICF-SW7600G, but since relative frequency difference is a lot smaller compared to the 49m/60m case, the effect isn't nearly as pronounced. On 60m, the AN-LP1 pretty much makes the set bulletproof, with an estimated 20 dB increase in image rejection.
There still is noticeably directivity on the 40m band, but it's pretty much gone an octave higher.

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Glossary

AM
Amplitude Modulation, also: mediumwave band (see MW), or (Sony) the whole LW/MW/SW range.
AGC
Automatic Gain Control (older term that basically means the same: AVC = Automatic Volume Control); a measure to ensure that stations are virtually always equally loud regardless of signal strength. Better receivers allow changing AGC time constants and even turning it off which may be helpful in certain DX situations.
BCB
Broadcast Band, see MW.
BTW
A harmless acronym: by the way.
Dual conversion
See IF.
DX
Originally meaning "distance unknown", this acronym is generally understood as reception of distant, hard to hear stations, or chasing for them.
FET
Field Effect Transistor. Commonly used in receiver front ends for RF amplification and mixing. On shortwave and lower, one typically uses n-channel junction FETs, while on the FM band and higher dual-gate MOSFETs are also popular (they can have very good noise figures up there, but are not so great at low frequencies due to high levels of 1/f noise).
FM
Frequency Modulation. This is employed by broadcast stations on the FM band (wideband FM, 150 kHz bandwidth) and the Citizen Band (CB) (narrow-band FM, ~10 kHz). On shortwave FM is basically only used above some 25 MHz (like CB on 27 MHz or part of the 10 m ham band), while it's a widespread standard modulation type on higher frequencies.
Ham
Infml.: radio amateur.
IC
Integrated Circuit; a compact part that offers the functionality of conventional circuits with separate capacitors, coils, resistors and all. A receiver like the ICF-SW7600G(R) uses ICs for demodulation (AM, Sync, SSB, and FM in conjunction with an external filter), for frequency synthesis (PLL), as audio amplifiers, and of course the microprocessor controlling the whole thing can also be seen as an IC.
IF
Intermediate Frequency (of a superheterodyne receiver). Superheterodyne receivers or superhets mix the incoming signal to a constant IF (after some RF pre-amplification, usually) which simplifies filtering enormously when compared to older concepts (superhets were invented in 1917 or so). Since the mixing process generates two signals twice the IF apart (see Image rejection), general coverage shortwave receivers use a rather high (1st) IF, however the higher the IF the more difficult / expensive it is to find good filters. Therefore they're usually dual conversion designs with a high 1st IF (which used to be just a few MHz in the days of tube receivers and lots of separate bands with bandpass filters, and is usually 45...70 MHz today with exceptions like the models with the "cost-effective" typical FM broadcast IF of 10.7 MHz allowing the use of FM IF filters there) which typically uses one or two crystal filters (typically 30, 15 or 8 kHz @-6 dB) and a lower 2nd IF with good filter choice (typically 455 kHz, or 450 kHz on older designs). This usually keeps image frquencies away pretty well, but very compact receivers tend to exhibit leakage issues around the 1st IF filter. Dual conversion receivers also have better dynamic range than single conversion designs built with the same efforts. (See IM.)
IFT
IF-level transformer. When tuned by means of parallel capacitance, acts like an additional LC filter circuit. Tuned IFTs on IF level are typically used to improve ultimate rejection and reject spurious filter responses.
IM or IMD
Intermodulation (distortion); a by-product of strong signals generated by amplifiers, mixers and the like when signals no longer fall into the linear working range. Attenuation of signals can help to eliminate the resulting "ghost stations" (and parts / circuits with better dynamic range, of course). On shortwave the most common types of IM products are 2nd order (usually found far away from the signals generating them, like at the sum of the frequencies of two strong stations) and 3rd order (found within or next to crowded bands). 2nd order IM products can be defeated rather easily with high-/low-/bandpass filters, so 3rd order IM products are seen as being more critical. Less expensive shortwave receivers tend to have wideband frontends, thus they can generate both types.
Image rejection
The ability of a superheterodyne receiver to suppress stations that are twice the IF (or one of the IFs) away.
Intercept point
This is a calculated value given in dBm that can be used to describe how good a receiver is in rejecting intermodulation products of a certain kind (mostly: 2nd order --> IP2, 3rd order --> IP3). The larger, the better. You'll mostly find the input IP3 published, which for many portables is below 0dBm and can reach +30dBm and more on very good receivers. Note that in practice with a high number of signals it's not always the mixer with the highest IP3 that performs best. In addition, you need to know where the input noise floor is (i.e. how sensitive it is when looking at a complete receiver) to judge dynamic range properly – a mixer intended for VHF use is likely to have a low intercept point, but it'll have a low noise figure, too.
LO
Local oscillator; oscillator that is used to generate one input signal fed to a mixer in superheterodyne receivers. It be noted that high LO levels tend to improve strong signal handling, but depending on the mixer may lead to overly high LO radiation (which for FM receivers is straight in the VHF air band).
LW
Longwave; the respective broadcast band (mainly used in Europe) ranges from 150 kHz to 281 kHz, with a 9 kHz channel spacing.
MW
Mediumwave; the respective broadcast band ranges from 531 kHz to 1611 (1700) kHz, with channel spacing being either 9 or 10 kHz depending on region.
PCB
Printed Circuit Board – the basis for all those ICs, capacitors, resistors and stuff.
RX
Receiver.
SSB
Single SideBand; see the ICF-SW7600G additional information section.
SW
Shortwave; generally the frequency range 3...30 MHz, contains various broadcast and other bands.

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Created: 2004-06-12
Last modified: 2014-04-01