Anybody feel like discussing Old Mopar/Motorola hybrid AM radios?

I find these quite interesting because they represent both the last dying gasp of the vacuum tube and its highest form of evolution before it was totally replaced by the transistor.

These radios used so-called "space charge" tubes, which used only 12 volts on their plates, in the front end and IF stages of the radio. This allowed Ma Mopar to get rid of the vibrator power supply that was necessary to produce the high B+ voltage for regular tubes.

The space-charge tubes performed only low-level signal amplification. The audio power amplification was done with transistors because, due to their low plate voltage, a space-charge tube can really only amplify signal voltage, not current; they can't handle more than maybe 50 mw. of power. The secret to being able to use such a low plate voltage is that the first grid after the cathode isn't used as a gate, like in a normal vacuum tube; it is instead biased so as to accelerate electrons toward the weakly-charged plate, rather than cutting them off as a regular grid would do. Physically, these tubes are called "miniature 7-pin button" tubes, which I think are smaller than regular 7-pin miniature tubes.

I've got a Motorola hybrid radio in my '62 Valiant V8 which doesn't work. I know that it is either a model 119 (the cheap model with no RF amp stage), or a model 203 (with an RF stage), but I won't know which until I remove it from the dash.

Would anybody be interested in a thread devoted to documenting, troubleshooting and repairing this radio?