Pocketful of Power: The Gonset Commander
    by Rick Ferranti WA6NCX; Arlington Heights, Massachusetts

    Introduction

    Surprising as it may seem, it wasn't until 1948 that hams were allowed to operate mobile on frequencies below 28 MHz. The new ruling spurred manufacturers to respond to a whole new market for ham gear. In the later 50's, familiar equipment like the Johnson mobile, the Morrow twins, the Elmac PMR and AF series, and the Gonset G-77 transmitter, G-66 receiver, and the G-76 transceiver, appeared to answer the burgeoning need for compact hf equipment operating all the way down to 160 meters. But it was the very first of this gaggle of Gonsets that broke new ground for compactness and light weight, and it's still hard to find any hf plate-modulated AM transmitter smaller or easier to carry than the Gonset "Commander," manufactured between 1952 and 1955.

    Faust Gonsett W6VR, was a frequent contributor to RADIO magazine (see Appendix) during the mid and late 1930's, often writing about a new ham transmitter design or a commercial adaptation of one, such as a diathermy machine. In the early 40's he joined his father's company1 and several years later designed a compact mobile/fixed station for six or two meters, the famous Gonset "Communicator." These were indeed hot performers for their time, with tunable superhet receivers, crystal-controlled plate-modulated AM transmitters running 5-10 watts output, and a modular design incorporating separate chassis for the AC/vibrator power supply, the receiver, and the transmitter. Known affectionately as "Gooney Boxes," and noted for their ability to hear VHF AM aircraft communications as well as the two meter band (the 5 MHz if and poor tunable front-end selectivity yielded a strong image response), Communicators are still seen at ham radio flea markets, sometimes painted garish Civil Defense yellow.

    After World War II, Gonset also marketed a hf mobile receiver converter series, first the "10/11," then others like the "Triband" and the "Super Six." The latter was a fine tunable hf converter, and it even became the heart of a mobile transceiver designed by Don Johnson WA6AAQ, as described in his book 40 Years of HF Mobileering. Appearing shortly thereafter, and not much larger than the converters, was the Gonset Commander transmitter.

    Anatomy of a Gonset Gem

    The Commander is a 30-50 watt input, crystal controlled 160 to 6 meter plate-modulated AM/CW transmitter measuring 8" wide by 5" high by 7" deep, about the size of two modest-sized paperbacks stacked on top of each other. It weighs all of 7 pounds, an easy handful for the weakest couch-potato ham to heft. Inside, a 6AG7 is the crystal oscillator/multiplier, driving a 6146 final, which runs as a straight- through amplifier below 27 MHz, and acts as a doubler on 10 and 6 meters. The final is plate modulated by a pair of push-pull class B 6AQ5's (in earlier models) or 7C5's (later production), driven by a 12AT7 mike amp/driver. The rig will accept either a carbon or high-impedance (crystal or ceramic) microphone.

    The rf section is a bit unusual. First, the 6AG7 crystal oscillator can be reconfigured for VFO operation by a front-panel slide switch. No, it does not become a buffer, but rather the 6AG7 accepts a series-tuned circuit at the front panel jack and becomes a free-running Clapp oscillator! The VFO that Gonset marketed for the Commander is thus a completely passive device. Though Gonset claims that their passive VFO was stable enough for operation even on 10 meters, I wonder if more FM resulted than AM. I've seen only one example of the Commander VFO at a ham flea market.

    The 6AG7 oscillator/driver is tuned over a 1.7 - 27 MHz range by a bandswitched tapped coil and miniature tuning capacitor. Grid current is indicated by a switched front-panel meter. But the final amplifier is tuned by a plug-in coil, accessed by a little front-panel trap door. Loading is accomplished by moving the coil tap up and down the plug-in output tank until the correct plate current is indicated by the meter at the resonance dip. The output tank tuning capacitor has a large, color-coded tuning dial, calibrated roughly in wavelength, so that with the proper Gonset coil the operator has little chance of tuning the final to the wrong harmonic. Two coils were provided with the rig, one covering 80 and 40 meters, the other 20 to 10 meters. A 160 meter coil and one for 6 meters were available separately. The plug-in coils and the rig's ceramic feedthrough output terminals could be configured for either coaxial or balanced feedlines. Despite its harkening back to the plug-in coil transmitters of the 1930's, this final output design allowed for very compact construction, and it adds a bit of quirky nostalgia to the transmitter

    Other front-panel controls include slide switches for tune-operate, hi-lo grid drive level (you need the higher drive capability when doubling in the final for 10 and 6), AM/CW selection, VFO/crystal operation, and power. Connectors include a FT-243 style crystal socket, the VFO input connector, and a 3/16" microphone jack. The rear-panel mounted mike gain control, power connector, and output terminals complete the control and connector complement. No antenna changeover relay is included. The rig can be wired for either 6 or 12 volt operation, and runs entirely on 300 volts, including the final amplifier. In fact, the manual cautions against higher voltage operation, giving elaborate details for connecting the then-popular 425 volt PE-103 dynamotor through dropping resistors so that the transmitter does not zorch over or burn up. With 300 volts running both low and high level stages, the Gonset Commander can be conveniently powered by a single vibrator-type power supply, or a simple AC operated source.

    For a lightweight transmitter the construction is remarkably rugged, with shielding and layout cleverly designed to maximize rigidity without adding weight. High quality components are used throughout (my 3 Commanders have had no smoked or failed parts); the audio and modulation transformers are shielded as well. This was not a cheap radio to build, but it was built to last - no wonder it cost $125 in 1952.

    Commanding the Airwaves

    Operating the Commander is very simple. After you get an antenna relay and PTT control system connected, you key up in the "Tune" position and tweak the grid for maximum current. If your crystal is a bit inactive you may have to switch to the high drive position for the required 2.5 mA grid current on the 6146. With the proper final amplifier coil plugged in and the little door open, you switch to "Operate," key down, and quickly swing the plate tuning capacitor through its range, tuning for a dip. To load, simply change the antenna tap point on the output tank coil, shooting for 100 mA plate current at resonance. Adjust the microphone gain for 100% modulation and you're on the air - oh yes, don't forget to check that you're tuned to the right harmonic on the final tank capacitor dial, and do close that cute little coil door. You can't get a 300 volt shock from the exposed windings (the coil is isolated from the 6146 plate voltage with a coupling capacitor), but the high-z side of the coil could give you an unpleasant rf burn.

    With the Commander running all of 30 watts input on AM and yielding about 12 watts out (10 watts on 10 meters), you're not going to blast through the QRM with shear power. But on a quiet band, the Commander really shines with fine, punchy audio, no doubt because of its integral high-level clipping which limits the modulation to near 100%. I've made contacts up and down the Northeast on 40 and 80 meters; on 10 meters the West Coast hears me fine (the antenna is a full-wave 80 meter horizontal loop about 30 feet off the ground, fed with a homebrew tuner). In fact, I was more readable with the Commander while talking with Walt KJ4KV 500 miles away on 75 meters, than was my neighbor Charlie KA1GON running 10 times the power with a much-audio modified Valiant and a dipole. I haven't tried to "improve" the audio with various mods; it doesn't require any work according to the reports I receive. In any case, running a stock rig lets others hear just how good the original design is.

    If you're looking for a compact mobile or fixed-station transmitter that pours out a first-quality AM signal, you will find just the ticket in a Gonset Commander. Mated with a suitably tiny receiver,4 the Commander forms half of what must be the smallest and lightest AM ham station money could buy. Its high quality, convenient power requirements, ease of operation, and fine signal make it a, worthy avatar of hf ham radio mobile, in the early 50's or 40 years later.