Receiver Review: Sony ICF-SW7600G

ICF-SW7600G

Year Introduced/Discontinued: 1995/2000
Power: 6 Volts DC (4 AA) or AC mains adaptor
Size: 191 x 118 x 32 mm
Weight: 615 g
Price: US$190, CAN$300, £130, A$500
Coverage: LW, MW, SW (continuous), FM

Value Rating: starstarstarstarstar


This review was compiled independently. The Medium Wave Circle and Radio Netherlands has no financial connection with Sony, the manufacturer of this receiver.


Reviewers: Jonathan Marks, Diana Janssen

 

Introduction

At first glance through a shop-window you could be forgiven for thinking that the ICF-SW7600G is just a cosmetic upgrade to its predecessor the ICF- SW7600 which has been around for a couple of years. Remember the so- called 7600 line has been around in various versions for ten years now. Back in 1984 the ICF-7600D was launched in most parts of the world, except in North America where is was known as the ICF-2002 to identify the US version from grey-imports from the Far East. By August 1987 the price had dropped to US$250 across Europe and with a change in colour it became known as the ICF-7600DS (or the ICF-2003 in North America). But the shortwave performance of all these radios was for all intents and purposes identical.

In January 1990 Sony upgraded its 7600 receiver re-naming it the ICF-SW7600, adding stereo to the FM portion of the radio and improving the single- Sideband reception on the ICF-SW7600. There was now a selector for upper or lower sideband rather than a fine-tuning thumb wheel. The price was still around US$250. With the launch of the ICF-SW7600G Sony has made a significant improvement to the receiver and cut the price by around US$50 in many markets, significantly more here in Europe where it now sells for £160.

 

Sync detection

The letter G in the new type number is very significant because Sony is the first to bring the price of a receiver with synchronous detection below the US$200 price barrier. The technique sounds complicated when you have to explain it to someone else, but in practice it is a feature which portable owners in the price class above US$350 have come to expect.

Most shortwave broadcast transmitters active today broadcast in what is called the AM mode which means that it consists of two components. The so-called carrier wave which puts the signal on a particular frequency, and two identical sidebands either side of the carrier frequency which carry the music or speech that you're trying the listen to. The carrier doesn't really carry any useful information with it apart from being a reference... most radios simply discard the carrier leaving the sum of the two sidebands containing the programming. The problem comes if you're listening to a weak signal that's just 5 kHz from a powerhouse signal that you don't want to hear. Take an example in Europe, namely on 6155 kHz is Radio Austria International, right next to the BBC on 6160 kHz. The upper sideband of Radio Austria International is sometimes swamped by the more powerful lower sideband of the BBC running on 6160 kHz.

A receiver with synchronous detection, like the ICF-SW7600G offers a possible solution. A very stable oscillator is used in the receiver so you can listen in a sort of "automatic single-sideband" mode. You select synchronous detection and the receiver's internal oscillator locks onto the carrier of the signal you're trying to hear. Now you can select the sideband furthest away from the interference, so in this case 6155 kHz lower sideband. Because the set locks onto the carrier you don't have to worry about adjusting controls to make the pitch of the music or speech sound normal which is something you'd have to do on a receiver without sync detection. Listening to a station using one sideband instead of two also reduces the problem of selective fading... especially during deep fades you notice there is less distortion if you are using the sync mode as opposed to AM.

 

Tuning

You can tune the radio by tapping in the frequency directly on the keypad and pressing an execute button... an improvement in fact over the ICF7600 which was a bit more clumsy. The key with the number 5 on it has a raised blip on it making it easy for blind listeners to orientate themselves and push the right key. That feature disappeared for a few years on the older ICF-SW7600.

You can also manually scan up and down the band in 5 or 1 kHz steps using cleverly designed up and down buttons arranged in arc shape. This idea appeared earlier this year on the more expensive ICF-SW100. You can scan automatically looking for strong stations too. The fact that the radio jumps up and down the band in finer steps than the older models and has a much stabler internal oscillator makes it much easier to tune in amateur radio operators using full SSB. You still have to clarify the signal using a thumbwheel on the side of the radio but it's much easier than in the past and the radio stays locked onto the signal without noticeable frequency drift.

 

Coverage

The ICF-SW7600G offers continuous coverage between 150 up to 29999 kHz in the AM mode and 76-108 MHz on FM covering the bands used in most parts of the world including the Far East. The version on sale in Italy has a chunk of shortwave missing (because it is used for military communications) and just the European FM band on it. On mediumwave the fine tuning step is 1 kHz and there's a small switch in the battery compartment allowing you to select between 9 or 10 kHz for the coarse tuning step. That's because radio stations in the America's are 10 kHz apart, 9 kHz elsewhere and if this feature were not available you quickly find it annoying if you jump from channel to channel to have to keep fine tuning all the time.

The liquid crystal display is clear, although it only shows the time when the radio is switched off and the frequency to the nearest 1 kHz when switched on. The radio has a dual timer function, but unlike the older SW-7600 there is no jack on the side of the receiver to operate a tape recorder. If you were using a Walkman-type cassette recorder to record what you hear then there's a line-output with a constant level. On FM though that output is in mono. You only get stereo reception on FM by plugging into the headphone socket.

The set now offers 22 memories, more than double that of older models. 10 are for AM, 10 for FM, and there are two which can be stored with the frequencies of favourite radio stations to wake you up in the morning.

 

Performance

When it comes to performance, the dual-heterodyne designs does well for a radio of this type. The intercept point is around -6dBm, but here in Europe we suggest you forget about an external antenna for night-time listening. In more remote parts of the world a simple long wire antenna might be required for improved daytime reception of higher frequencies. Any overloading when using the telescopic whip antenna can easily be reduced by collapsing the antenna a bit. The set comes complete with a washing-line type of antenna which is useful on trips.

 

Bandwidth Filters

The ICF-SW7600G is certainly selective enough for international radio listening. The filter specifications are tighter than on previous models and that is noticeable in a slightly more muffled audio. The sync detection mode compensates for the lack of a second bandwidth filter. There have clearer been changes to the audio section of the receiver. Battery consumption is down to 50 milliAmps at normal listening levels, and we got about 23 hours of life out of a new set of four alkaline batteries. One reason for the price drop in some countries is due to the fact that the AC power supply is no longer included in the package. The ICF-SW7600G uses the new-style Japanese 6 volt DC power standard so if you do buy a separate power supply check that it has the new smaller type of plug and that the polarity is correct. The batteries should be kept in the radio at all times, even when an external power supply is connected. This ensures that the stations programmed in the memory are retained. You have around 10 minutes to change the batteries before the radio resets itself.

A two position tone control is active on both AM and FM. It simply cuts the treble response when activated. Like older models, the radio has a cleverly designed ON/OFF switch which can be locked. This is useful when the set is packed in a suitcase and you don't want it to spring to life when knocked about.

 

Conclusions

The Sony ICF-SW7600G is a very clever package at a reasonable price. So far, no one else has managed to offer the synchronous detection feature on a radio under US$200. Performance on the ICF-SW7600G is similar to the new and much more expensive ICF-SW100, but without the extended page by page memory tuning. We think the identically priced Grundig Yacht Boy 400 sounds better on its own internal speaker. But as far as dynamic selectivity is concerned, the sync feature on the Sony has the edge and the synthesiser noise is lower. In March 1995, this receiver was given the Award for Technical Innovation.

Special Note: A copy of the manufacture's manual for this receiver is included on Vol 51 of our archive CD's.

This review first appeared on the Radio Netherlands website.