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  1. ICF-SW7600GR - the current model
  2. ICF-SW7600G

ICF-SW7600GR section

[ICF-SW7600GR pic]
The latest model ICF-SW7600GR (from [11])

This is the current model of the 7600 "family". The specs hardly differ from those of the 7600G, except for the number of presets (100 non-volatile instead of just 20 that are lost if you leave out the batteries for too long), a variable attenuator and various other smaller improvements (they're listed under "Pros" and "Cons"). The on/off switch has been changed: While before it was a combined slider and switch, it now is a normal switch only, however, the receiver's functions including on/off can be blocked with a separate "HOLD" slider which has also replaced the "KEY PROTECT" button. The actual performance is said to be very similar to the SW7600G, so it seems there weren't many changes made in the HF portion. Concerning the name, I suspect it's supposed to say that the radio is a "7600G Revised".

General information

Pros (when compared to the SW7600G model)

Cons (when compared to the 7600G model)

Reviews

Additional information

Since the 7600GR is quite similar to the 7600G below, much of the additional information and tips for this receiver should also apply to the newer model.

Operating and service manual

Manual downloads at Sony - ICF-SW7600GR, ICF-SW7600G, ICF-SW7600, ICF-7600D

Service manual at RigPix (local copy)

Links

Yahoo! Groups:

DRM modification for the SW7600GR

A few measurements

These numbers were originally from the 2002 WRTH and partly posted on "7600group". Take them with a grain of salt, I personally don't really trust them.

Measurements weren taken with an AM signal with 70% modulation carrying a 1 kHz tone; sensitivity was measured at 10 dB S+N/N.

Sensitivity:

 MHz  µV
   5 1.2
  15 1.0
  25 1.1

These are some rather good sensitivity figures for such a portable. I'd assume the 7600G is similar. The reviewers noted that sensitivity is reduced on the EXT ANT input, another feature common with the previous model (probably supposed to reduced IM problems on external antennas).

Selectivity:

  -6dB        AM  7.3 kHz
 -60dB        AM 13.1 kHz
  -6dB Narrow AM  3.2 kHz
 -60dB Narrow AM  8.3 kHz

The somewhat irritating "Narrow AM" means SSB. Apart from that, the "wide" measurements are surprisingly close to those obtained on a standalone SFR455I filter (7.1 kHz/~13 kHz @-6dB/-60dB); see the 7600G filter information.

The review noted an ultimate dynamic range of about 80 dB, not too shabby for such a receiver.

Now it gets really weird:
Image rejection: 83 dB (but spurious response at +13.7 MHz only -40 dB)

Okay, the receiver is apparently not that IM proof (not a big surprise, given the 7600G didn't fare so well there either), but it never has that good an image rejection. 83 dB is an excellent value reached by much more expensive tabletops, but way out of reach for a small portable, particularly considering that the predecessor which doesn't differ much in the HF portion only shows an average value of around 40 dB. Also, Passport to World Band Radio mentioned "adequate, but not excellent" image rejection. Possibly the WRTH measurement refers to 1st IF (i.e. +111.69 MHz) image rejection?

Weird "localized" versions

I already knew the Saudi Arabia models with limited frequency ranges and no SSB, but the Chinese version not only with no EXT ANT jack (OK, old issue too), but also a non-functional DC power connector (!) was new to me (although apparently there had been one for the 'G' already, from ~1998 onwards). What the point of this should be is beyond me. Thanks for any insight (contact at bottom of page).

ICF-SW7600G section

[ICF-SW7600G pic]
ICF-SW7600G (from [8])

General information

What's positive?

  1. The receiver is easy to use - the solution with the 4 tuning keys is good, and entering and recalling frequencies is pretty simple.
  2. Keys in general: very good, you know exactly whether you have or you have not typed something in. Some people were concerned that the keys would fail soon, as the same kind of buttons were used in the old ICF-2001, the first digital shortwave receiver on the consumer market, which suffered from key failure, but as yet, all the keys are still working perfectly (I've owned my 7600G for 5 years now), and I haven't heard anything about key problems either (the receiver was in production for some 7 years and first introduced 9 years ago [as of 2003], so failures of that kind should have shown up by now). Only the paint on the tuning keys of my receiver is a bit worn off by now, and it seems I'm not alone with that problem.
  3. Good selectivity.
  4. Low LO phase noise, as indicated by DRM SNRs of up to 27 dB on modified sets.
  5. Best-in-class SSB reception - as opposed to most other compact portables, its product detector is sideband selective. Other-sideband AGC pulling still is annoying but one cannot expect true SSB filters in this league.
  6. The power consumption is also quite low (though the "battery champ" appears to be the Sangean ATS-505).

And what's negative?

  1. Lousy speaker audio - it's still halfway OK for speech but no fun with music. Any of the older models fared better. I wonder where the portable radio folks at Sony mislaid their audio engineering knowledge in the 90s - though admittedly there is not a lot one can do to make a cramped set like the SW7600G sound great. One would at least need to free up some space behind the speaker to enable dipole radiation.
  2. While there is no muting on 1 kHz steps, there is no tuning knob - this is not the bandscanner's dream set. Manual tuning still is fast enough for ham bands (about 18 kHz/s) but not that much fun on the broadcast bands. It admittedly could be worse (see ICF-SW30, which limps along at less than 8 kHz/s on shortwave and neither offers 5 kHz steps nor direct input).
  3. Muffled AM audio - this is somewhat better with sync on, but weaker stations where that doesn't work too well can be quite frustrating to listen to. Honestly, any of its predecessors that I've listened to since (ICF-SW7600, ICF-7600D, ICF-7600A) fared better (but unfortunately, none of these had an external antenna input, as the PLL tuned sets were German market samples), as does the Redsun RP2000 with its adjustable tone controls. The SW7600G's tone switch only allows selecting between muffled and more muffled, which is hardly helpful.
  4. Unexciting image rejection for the 2nd IF (some 40 dB) - this appears to be rooted in the very compact nature of the receiver, where RF leakage around the 1st IF filter is easily possible due to everything being rather cramped on the PCB; the ICF-SW77 employs two such filters with a fair amount of distance and ground planes between them, just adding another one to the 7600G(R) merely yields 6 dB better image rejection, i.e. virtually nothing.
    Thankfully the AN-LP1 antenna with its quite sharp 5 MHz range managed to free at least 60m from images and improve signal levels quite a bit.
  5. The sync detector generates noise of its own and fails to lock on weak signals - that's what a sync detector is certainly not supposed to do! Normally sync detectors help with weak stations with fading, but in this case only the sideband separation can be used. If there is a weak station with interference, SSB should be used, which is much easier to do than with the older models.
  6. On batteries, sensitivity straight off the whip isn't too exciting due to lack of an RF "counterweight" (ground). Connecting a power supply, RF ground or using an external antenna helps.
  7. The power supply jack is prone to connection problems - it is soldered directly onto the circuit board, which means mechanical stress may damage the solder joints or even the PCB. If such a connection problem occurs, the jack needs to be resoldered.
  8. Due to the wideband frontend for shortwave, 2nd-order intermodulation products may show up in strong-signal areas at times when the bands are crowded, even on the whip. (In this price range, you cannot expect extensive frontend filtering - SW55 and SW77 had approximately octave bandpass filters.) In this case an antenna tuner / preselector is quite helpful (I still have an ADDX PRE-1), which may increase real signal levels at that due to - you guessed it - improved antenna tuning. Likewise, using a tuned external antenna (Sony's own AN-LP1 has been serving me well, and not only with this receiver) eliminates these issues even better.
    Of course, this all is far less critical in areas with low signal levels on shortwave - there you can often use antennas of a few dozen meters without getting intermodulation, and with a preselector it should be possible to use monstrous antennas. Don't forget the lightning protection BTW!
  9. SSB generally sounds good, however, the receiver seems to get instable on high frequencies - strong stations especially on 10m sound "wobbly". Apparently this is related to a slowly-locking PLL in these regions, which then cannot compensate for the VCO being influenced by signal strength in some way. (Rather empty batteries cause this phenomenon to trickle down to lower freqs; the sync doesn't work well then either.)
  10. The antenna seems to be pretty robust, but the joint obviously isn't - on my receiver, the antenna suddently could be rotated very easily and now tips over all the time; I've even heard rumors of ones falling off.
  11. The small and slightly recessed slider switches on the side of the receiver aren't exactly suited for people with big hands. (On the preceding model, they stuck out some more.)
  12. The receiver lacks a meter band display (the ICF-7600D/DS had one), and the time is only displayed when the radio is off.
  13. The 7600G is no FM DX machine - it gets overloaded quite easily on FM, and the stock filters are w-i-d-e.
  14. Perhaps it's just mine that's affected, but the rx likes to hum on strong stations particularly when used with an AC adapter. (The AN-LP1 seems to help in this regard.) Supposedly that's more related to the power supply though, more specifically a badly suppressed resonance in the transformer's secondary.
  15. Stereo output is only possible with headphones plugged in, even if using the rec out jack (the reason is a small switch in the headphone jack that is used for disabling the speaker and switching the circuit to stereo).
  16. Weak bass reproduction even on headphones due to overly small coupling capacitors (see the 7600G tone mod) - this contributes to the overly mid-centric AM audio.

Reviews

  1. The review by Radio Netherlands
  2. A user review by David Knisely
  3. Another user review by Adam Trent Phillips
  4. Dave Z's review and comments collection
  5. Test aus dem FUNKAMATEUR - PDF (38 KB)
  6. eHam.net reviews
  7. My take of the SW7600G in 2007

Tips

General tips

Information on tuning in SSB stations

Q:
When trying to tune in SSB stations, all I hear are Donald Duck like voices. Am I doing something wrong?

A:
You'll have to be aware of the fact that SSB can be broadcast in either the upper or lower sideband (set the switch on the right accordingly - generally most utility services use USB, while hams below 10 MHz mostly use LSB), second the 1 kHz steps are more than just a bit coarse for SSB, so you'll have to use the fine tuning control.
I recommend leaving the fine tuning control in zero position most of the time (just tune to a broadcaster with a stable frequency [in Europe: perhaps the BBC or Deutsche Welle] and adjust the control so that it sounds normal), since quite often hams and utility services use full kHz frequencies. If it sounds strange anyway, you can still switch to the other sideband (remember to re-tune the receiver by about 3 kHz [1]) or adjust the fine tuning control (carefully). You'll soon get a feeling for that.

[1] Why? That's pretty simple. Imagine an AM signal like that:

 ^ amplitude
 |         __   |   __
 |        /  \  |  /  \
 |       /    \ | /    \
 |      /     | | |     \
 |_____/______|_|_|______\________ Frequency

          (1)  (2)  (3)

(1) Lower sideband = LSB
(2) carrier
(3) Upper sideband = USB

Both sideband carry the same information and are symmetrical with regard to the carrier, i.e. the lower tones are close to the carrier, the higher ones further away.

An SSB signal looks like that...

 ^ amplitude    
 |         __   |      
 |        /  \        
 |       /    \ |      
 |      /     |         
 |_____/______|_|_________________ Frequency

          (1)  (2)

(1) Lower sideband = LSB
(2) carrier frequency (unlike in AM, there is no carrier, and the information is only transmitted once - single side band)

...or like that:

 ^ amplitude
 |              |   __
 |                 /  \
 |              | /    \
 |                |     \
 |______________|_|______\________ Frequency

               (1)  (2)

(1) carrier frequency
(2) Upper sideband = USB

If you're receiving an SSB station sending in the LSB, the ICF-SW7600G(R) will show the frequency of the "carrier" (which does not really exist, of course), and if you switch to USB, there will be nothing to hear. You'll have to tune down a few kHz to hear the station again - of course bass and treble will be reversed then, which might just be what is needed to understand something.

Additional information

Service and Operating Manual

ICF-SW7600G service manual (3 meg zipped PDF)
Thanks to OM M. Reneman from .nl for sending me this.

Manual downloads at Sony - ICF-SW7600GR, ICF-SW7600G, ICF-SW7600, ICF-7600D

Links

Yahoo! Groups:

DRM modification for the SW7600GR, with notes on SW7600G differences

The IF filters

AM IF filter

Murata ceramic filter SFR455I (which might be the same as a CFWS455IT, the current P/N of which is CFWLA455KJFA-B0), a 6 element part with a nominal -6 dB bandwidth of 4 kHz. In addition there's one tuned IFT.

Measurements on an SFR455I with professional equipment indicate bandwidths of 7.1 kHz at -6 dB and ~13 kHz at -60 dB (-60 dB value may not be exact since the ultimate rejection isn't much higher) - a form factor of 2 is certainly not bad at all (and makes these filters look very well chosen), but we can safely assume that the actual selectivity will be limited by other factors such as phase noise (oscillators usually don't produce one clean frequency, but rather a whole spectrum around a main frequency; the faster these unwanted other frequency parts decay when you go away from the main frequency and the lower their amplitude is at a certain distance, the better is the oscillator) and leakage around the filter (which usually limits ultimate rejection). (See Radio Netherlands' measurements on the ICF-SW7600 which uses the same filter.) If the default bandwidth is too wide for one's taste (I rather like it, since I'm more into program listening with the little Sony), it can be replaced by the SFR455J, a nominal 3 kHz part measured with 4.5 kHz at -6 dB and ~9.5 kHz at -60 dB.

FM IF filter

Murata ceramic filter SFE10.7MA (nominal bandwidth: 280 kHz), 2 pcs.

The receiver contains two FM IF filters. I've had mine replaced with 110 kHz (SFE10.7MJ) and 150 kHz (SFE10.7MH) parts, respectively. (More precise P/Ns - the "7600group" on Yahoo! Groups is quite helpful btw - : SFE10.7MJA10-A / new SFELA10M7JAA0, SFE10.7MHY-A / new SFELA10M7KAH0) I don't know whether the radio is an FM DX machine now (I suspect rather not, since it's still rather sensitive to overload), but a quick tour through the FM band showed that indeed selectivity is quite good, separation of two stations 200 kHz apart didn't pose much of a problem.

On the 1st IF at 55.845 MHz, the 7600G(R) uses a nominal 15 kHz crystal filter.

Radio Netherlands' findings

Intercept point (3rd order): around -6 dBm
Power consumption:
(at "normal volume")		 50 mA
Battery life:
(new alkaline batteries)		 23 hours

(Seems power consumption was measured on FM, for the AM ranges 65 mA is more realistic, or 80 mA like the review in FUNKAMATEUR says.)

Power consumption

While we're at it, reader John Perkins from the US found that his 7600G purchased in 2000 consumes, on average,

depending on modulation and volume.

About the ripple filter

The following information is from a rec.radio.shortwave discussion (subject: "Ripple filter-7600G"), from the messages <3AA959CA.F9AA8EE0@sympatico.ca> (by Gus G.) and <3aaa8319$0$613$5a62924d@news.skynet.be> (by Bucki Slawomir), respectively. (You can search for message IDs via groups.google.com (formerly deja.com), in case you didn't know.) IMO it gives some insight into the problems of the construction of small radios.

[...] Looking at the schematic the DC input to the radio goes through a ripple filter. This ripple filter uses 3 transistors. 2 transistors are tied at the base to ground. And the bases of these transistors are in turn tied to the emitter of the other transistor. Can someone explain what is the purpose in using transistors as part of a ripple filter instead of say a capacitor. I have never seen this before.

they are part of an "active capacitance" circuit. an "active capacitance" circuit is comprised of a capacitor [and] a transistor and behaves like a large capacity capacitor to do ripple filtering in a voltage regulator circuit - but is much cheaper (and takes up less space) than a classic large capacity electrolitic capacitor.

About the antenna circuit and external antennas

The following information is from an older posting, <38EB4AAD.7C7D5EC6@yahoo.com>:

  1. The ext. antenna socket is "hot", i.e. powered through a 470 ohm resistence + 100 uH coil. This means that it will deliver approx. 10 mA DC current to the external antenna circuit. The coil is to prevent "polluting" the power circuit of the radio with radio frequency signal. Evidently, the purpose of this arrangement is to "inform" the accessory antenna when the radio is turned on. In case of the Sony AN-LP1 it turns on the antenna without need to use the antenna power switch. However, the 7600G will NOT power the antenna, the 10 mA are not enough to power the amplifier circuit. The power for the AN-LP1 comes from its own batteries. You can use this feature with any active antenna by including a proper power-up circuit - a nice feature if your active antenna is located far away from the radio and you want it to turn on and off automatically when you use your radio.
  2. You can connect any other antenna (provided it is correctly designed and installed) to the EXT ANT socket without risking to damage the radio. However, if the external antenna circuit has low DC resistence, it will drain some current from the radio. Therefore, you will experiment slightly higher power consumption from your batteries (up to 10% at normal listening volume). You can avoid this current drain by including a small ceramic capacitor (1000 pF) in series with the antenna circuit, however I don't think it is really necessary.
  3. The 7600G has some basic protection build into the EXT ANT input circuit. Any static buid-up will be drained off via the power circuit mentioned in point 1. It also includes a diode pair (1SS123) to protect the input RF amplifier FET from damage due to too strong signals or an accidental connection of the antenna to a low voltage AC source. IT IS NOT A SUBSTITUTE FOR A PROPER ANTENNA GROUNDING AND LIGHTNING PROTECTION IF YOU USE AN EXTERNAL ANTENNA - YOU STILL NEED TO PROPERLY GROUND YOUR EXTERNAL ANTENNA AND PROTECT YOUR RADIO, but it builds some margin of safety to protect the front-end FET - a common problem with the Sony 2001D (2010).

The power connector

Contrary to what a number of people believed when the ICF-SW7600G was new, the different power connector (compared to older models like the SW7600) was not intended to make people buy Sony's quite expensive power supply, but in fact the result of an EIAJ (Electronic Industries Association of Japan) norm for power connectors on consumer electronics published in 1990. In case of the ICF-SW7600G(R) this means:

Information about sync detection

Serial numbers

My own ICF-SW7600G, bought approx. in March 1997, carries a S/N of 157792 - and yours?

Reader John Perkins mentions his 7600G bought in May of 2000 has a S/N of 275749. This would mean that production barely reached 300000 (or maybe 350000), assuming it didn't sit on the shelf for too long. The largest serial number reported to date was in the 326xxx range.

A wishlist for the successor (predating the ICF-SW7600GR):

Important things:

Less important things:

Next: ICF-SW7600 →

Quick links

Write to the author (Stephan Großklaß, "Grossklass" in 7 bit)!

Created 1999-06-01 (yyyy-mm-dd)
Last revision 2010-02-11