In late 1952, Gonset introduced the Super 6 Converter designed for receiving six HF ham bands in four switched ranges covering 75, 40, 20, 15, 11 and 10 meters as well as the 19 and 49 meter shortwave bands. A 1953 Gonset ad speaks of the Super Six as "the successor to the famous Gonset Tri-Band". All of the converters were designed so that the car radio provided B+ and the remainder of the receiver. The Super Six output was 1430 KHz to which the car radio was tuned allowing for dual conversion. Designed by Faust Gonsett, the Super Six and the other converters follow the Gonset philosophy of a high quality but very compact design. The converters measure only 5 and 1/4 inches wide and deep and 3 and 3/4 inches high. Gonset later also came out with a companion "Super-ceiver" Model 3041 for the Super six which eliminated the need for a car radio. It provided power, voltage regulator for the Super Six oscillator, crystal controlled IF, audio chain, BFO and controls such as RF gain and squelch for making the Super Six a complete ham receiver with much better selectivity and stability than simply using a car radio.
The Tri-Band and the "Super Six" share not only their looks, but also much of their circuitry. The antenna jack and output cable use the Motorola jack and plug, as was common in car radios. The car radio was tuned to 1440 KHz (1430 for the "Super Six"). The Gonset was then switched from the straight-through position to one of the selected shortwave or ham bands.
Tubes in the converters are 6CB6, 6AT6 (or 6AV6), 6C4, and 6BH6.
All of the slide-switches were frozen in place and refused to budge with a gentle tug. I did not force them as I did not wish to break any. The band switch was also difficult to move. Deoxit solved the problem. I checked continuity on the switches afterwards. No problems. The chassis and the cabinet cleaned easily with white waterless hand cleaner. Deoxit was also applied to the variable cap rotor-to-ground feelers and the tube sockets. Testing the tubes found all to be in good order. Note that the chassis picture above shows one of those "dreaded" Sprague Black Beauty capacitors. However, it is across the 6 volt filament line. Yes, I purposely left it there.
I used a little Heathkit EF-1 power supply to provide the filament voltage and B+ power. Under load, the B+ measured about 125 volts which was about what the set was needing.
Trying out the converter
These converters were designed to be used with a shielded car radio. I connected a car radio and made sure that it was perfectly tuned to 1430 KHz using a signal generator and frequency counter. The Super Six has a wire intended for optional AVC connection to the car radio. I left it disconnected. The converter worked quite well although the oscillator needed some alignment. The Super Six manual does not give details for alignment. The 75, 40 and 10 meter trimmers affect those bands only but the adjustment for the 15 and 20 meter range trimmer on the rear panel interacts with the other ranges and should thus be adjusted first. I then adjusted the lower 2 ranges by simply monitoring the converter's oscillator with a frequency counter adding 1430 to the dial indication for correct alignment. The alignment held quite well for each marked ham band coverage. The two highest ranges apparently use harmonics of the oscillator frequency. I aligned those with a signal generator.
All these converters are only useful for AM since they preceded wide acceptance of SSB. I found a couple of AM ham QSO's but found the 19 meter daytime and 49 meter nighttime shortwave bands had plenty to listen to. The converter worked quite well with just a short wire antenna but not surprisingly really came alive when connected to my 80 meter ham antenna. The short antenna would be more typical of a car radio antenna or mobile ham antenna.
It is relatively easy to build a BFO circuit so that the car radio (or other connected radio) can receive SSB and CW. Tom W0EAJ has done exactly that, re-purposing a radio-phono chassis and adding a small homebrew BFO for 455 KHz. Here's a PDF writeup on his project
Converters meet the Commander
The Gonset Commander was originally designed for mobile use with one of little Gonset converters such as the Tri-Band or the Super Six. Note the similarities in design. The Commander was happy to see his brand-mate converters from the days of mobile AM ham radio.
The manual for the Super-Six can be found on BAMA. Click here for a link to BAMA and other manual sources. The Super-Six manual addendum details the connections needed for conversion to 12 volt power and also mentions using a 45 volt battery for the B+ supply when using the converter with the "new" 12 volt-only car radios (radios that use 12 volt space-charge tubes and solid state audio output).
"Fun With Signal Generators"
article as written for "Monitoring Times" magazine was the previous project.