[Swprograms] radio review

["Eric Floden" <eric.f99999@xxxxxxxxx>]

from the wonderful Cool Tools site, this review

 

http://www.kk.org/cooltools/archives/003464.php

 

starts out like this

 

Best portable, shortwave receiver

01-14-09

Sony Shortwave Radio

The previously-reviewed Sony ICF-2010 is undoubtedly the best portable shortwave radio ever made. It was built to perfection with synchronous detection, aircraft band and a lot of other bells and whistles. But unfortunately, it has long been discontinued. Likewise, the previously-reviewed Grundig YB-400 has also been discontinued.

Today, the two best portable shortwave receivers in the market are the Sony ICF-SW7600GR and the Grundig G5. Both are great radios, but the 7600GR triumphs over the Grundig because of its excellent build quality (still Japanese made!) and synchronous detection circuitry, which lets the user eliminate adjacent channel interference, fading and distortion on shortwave. Both are equally sensitive on shortwave but some argue that the G5 has better audio (i.e. the speaker). For listening to ham radio stations, though, the 7600GR is much better and, at least for the moment, it is the only portable receiver that features synchronous detection circuitry, technology usually found only on radios *ten times* the price!

Some background on synchronous detection: an Amplitude modulated (AM) signal has three components: the carrier signal which is flanked by upper and lower sidebands (USB and LSB). The sidebands carry the audio information and are prone to interference when a station from an adjacent frequency interferes with the sidebands. For example, if you are listening to BBC on 9500 KHz, a station at 9505 KHz might interfere with the upper sideband of 9500 KHz but not with the lower sideband. The lower sideband is vulnerable only to a frequency lower than BBC at 9500 KHz. A regular detector on a radio like G5 will take *both* sidebands and the carrier signal and generate an audio that will show signs of interference. A synchronous detector like the one on the Sony 7600GR eliminates the distorted sideband and uses the cleaner sideband (the one not affected by interference) and mixes it up with a new strong carrier signal, which it generates by itself. Thus, the 7600GR eliminates two problems: weak carrier signal and distortion of the sidebands due to adjacent channel interference.

 

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-- Sam Ponissery

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