The Superadio Plus: A Report

T. David Zimmerman

I have been a long time fan of long-distance performance radio receivers. As a matter of fact, I collect many such radios which were made by American and German companies in the 50's and the 60's. My favorites have been the Zenith "Long Distance" AM/FM models of the period. Since the demise of the tube receivers however, the emphasis in the market place has shifted away from RF performance in favor of such things as stereo, portability, cassette recorders and especially CHEAPNESS.

This has made enthusiasts like myself and others look for what the market had to offer using solid state components. The closest thing one could find in the 70's was a Panasonic. They were offering surprisingly good small radios at a reasonable price. I do enjoy those but even the Tech Series Panasonics emphasized other than straight AM/FM performance. Sony and Sharp also had some fairly impressive small radios. The best of these radios did utilize state of the art technology in their IF filters and such but still did not employ basic receiver techniques such as separate oscillator and mixer and an RF stage.

Finally, in 1979, GE of all companies, announced the first Superadio (model 7-2880). The idea of such a radio which boasted tuned RF stages on AM and FM, a ceramic FM IF filter, 4 stages of AM IF tuned circuits, 6" speaker and a 200 mm ferrite loopstick antenna was very intriguing. Knowing what GE had offered previously and how they could not hold a candle to Panasonic did make me skeptical. Nonetheless, when I tried one in a department store I was able to receive numerous FM stations with the antenna down. Maybe it really is good, I thought. Needless to say I acquired one. My wife surprised me with it on my birthday in 1981. We were living in Easton, Pennsylvania at the time were there are FM's at 95.1 and 96.1 MHz--a selectivity problem for anything in between and an intermodulation problem for 94.1 and 97.1 MHz. The radio pulled in WFLN-FM from Philadelphia @ 95.7 MHz with the antenna down and WPLJ, 95.5 MHz from New York with the antenna properly positioned. Yeah, OK, but can it do AM. Yes it can; its sensitivity handly blew away the Norelco portable I had been using as a benchmark. The DAYTIME dial had few gaps. The lowest dead frequency was 640 KHz.

I knew things were different now! I joined the small army of Superadio enthusiasts to spread the word that there was finally a decent new radio for AM/FM reception. It listed for $79.95. No, it doesn't play tapes and it isn't stereo but no other portable you could find could even touch it for RF performance.

In 1982 GE introduced a new model, the Superadio+ (model 7-2882_). This one boasted many of the same performance features (RF stages, IF filters, 6" speaker, 200 mm ferrite antenna). The difference was it was digital. Yes, A PLL synthesized Superadio! This one was pricey. $139.95 retail. At first, I passed. Apparently the Superadio+ didn't sell as well as the analog model because after a mere year it was already available for the closeout price of 54.55. At this price my wife and I bought one at a Murphey Mart in West Virginia.

Compared to the analog model, the performance is close but with some sacrifices. There is a noticable increase of noise on AM when DXing requires maximum sensitivity, most likely directly related to the synthesizer. FM capture is good but sharply loses lock below a certain signal strength below which the analog radio can still receive. There are eight presets on each band, scanning features and a lighted display, but no direct frequency access. There is a switch on the back to allow the radio to tune in 9 KHz spacing for European use. The station memory requires 3 AAA batteries.

The all-time best seller among Superadios was the Superadio II (model 7-2885). This was an upgraded version of the first analog model. Obvious changes included the addition of a piezo tweeter, more chrome and a flatter speaker grille. Also depending on which revision letter follows the model number on your particular radio, later earphone outputs accepted stereo headphone plugs. Less obvious were the change in IF amplifier coupling and some device changes inside. Also, later revisions used a different variable capacitor but still 6-gang. I have tested many of these radios and compared them against my own and another original Superadio.

Compared to the original, the AM IF gain on the SRII is increased, the FM sensitivity is improved and selectivity is somewhat better on both bands. FM capture on the original is somewhat more friendly however. The actual tracking of sensitivity across the AM band seems to depend as much on the individual unit as it does the model. For AM sensitivity measurements I always use daytime signals because night skywave DXing brings questions of masking, AVC variation, antenna polarization and selectivity into the equation. My measurements use the built in ferrite for AM and the whip for FM. No external antennas. As for the sound, the frequency response is quite wide but the bandwidth available in the audio amplifier is in excess of what should be expected from a 700 mW amplifier and much of the low frequency information is wasted on a speaker that is inefficient at the low frequency extreme of the amplifier. Using the bass and treble controls to contour the sound helps a little.

Finally when Thomson bought GE and after about 10 years of Superadio IIs, a new model was introduced, The Superadio III(model 7-2887_). This model is more plastic-intensive than any other SR and is the most hollow, too. The first production of this model, roughly through March of 1993, had serious sensitivity problems. At that point I had only tested someone else's radio but was so disappointed that I wrote to GE to tell them they had made a mistake with the varactor tuning. The varactor tuning in the front end of the receiver represents the most significant change in the model compared to the SRII. Later I started to hear that the problems had been fixed and the Superadio III really was good. So, my wife bought me a Superadio III for Christmas in 1994. I made sure the date code was of the period that was not affected by the earlier problems. Sure enough, this SRIII was much better than the first one I tried. Compared to the SRII this one has a better amplifier to speaker match and therefore gets better sound out of the same 700 mW amplifier chip. The AM (MW) now extends to 1700 KHz in hopes that the congestion will someday be relieved in the rest of the band by reassigning some stations up there. SRIII also has a wide bandwidth setting for extended audio response. This does make local stations sound good but, of course, fidelity sacrifices selectivity and sensitivity suffers quite a lot as well. The narrowband setting has good selectivity, especially at the low frequency end of the band. Based on several units tested, there is quite a bit more internal noise on the AM with the SRIII than with either of the other two analog models. There are a few new birdies too. This means that the most demanding DXing needs will favor the older variable capacitor-tuned Superadios for sensitivity. This sacrifice is undoubtedy the result of the increased noise figure of the varactor-tuned front end as well as the inability of all the varactors to track well over the required two and a half octave tuning range of the AM band. The tracking error also contributes to the absolutely abysmal dial calibration of the SRIII.

The FM on my SRIII is very nice. It can be hard to tune at the upper end because the mechanism is sloshy but the selectivity is good and the intermod and image rejection characteristics are better than with the SRII.

How do Superadios stack up to other high performance models? Compared to older multiband models like the aforementioned Norelco and the ultra-state-of the-art models like the Sony ICF-2010 (and even supposedly the Bose Wave radio), it is clear that the emphasis on AM/FM radio receptions makes the Superadios the best at what they do. Multiband radios optimize the IF bandwidth for shortwave reception and can sacrifice BC sideband information with selectivity merits that do nothing to improve AM BC reception. Boom boxes usually have trashy radios because the emphasis is on stereo, tapes, CD's etc. The one thing the Superadios still can't do quite as well is the good old fashioned brute force sensitivity of a well designed tube radio. The wide dynamic range and quiet, high impedance amplifier stages in good tube radios has still not been matched even in the world of shortwave reception. Solid state receivers require a higher degree of complexity to accommodate dynamic characteristics that are inherent to tubes. Of course, tubes are less reliable, power hungry and more expensive.

I like all good radios. Superadios provide the best reception available in today's market and at a price that anyone can afford. I own all four of the Superadio models and I know others who have even more.

T.David Zimmermann
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Last updated on April 4th, 2003