Garage sale find: GE P1700A 10 transistor

[wa2ise]

It works! 10 transistors, a few are used in questionable purposes (or maybe my radio knowledge has gaps!) One is a "rejection regulator", its collector tied to the local oscillator coil tap, the base and emitter tied to ground (seems that transistor would do nothing like that, well maybe the base-collector junction would act like a diode to clip excessive oscillator amplitude and via emitter follower action clip excessive radio station amplitude). Another transistor is a detector diode. And another looks to be a temperature compensator for the audio output transistors. The first IF amp is a grounded base amplifier configuration, the first IF "transformer is actually a series LC circuit that would be what you'd use to drive a low impedance emitter. The converter transistor feeds a tap on the coil section.

This radio uses that strange circuit board technology GE liked back in the late 60's. A single sided board with plated thru holes. This radio shows up in the 1966 Beitman's.

[Celt]

As you already know...it wasn't uncommon back then to use 6 transistor circuits and stuff them with useless transistors.
Bragging rights you know.

[wa2ise]

Originally Posted by Celt

...it wasn't uncommon back then to use 6 transistor circuits and stuff them with useless transistors.

Here's one where they ran up the count from 7 to 12:

They soldered in pairs of transistors (base to base, emitter to emitter, collector to collector) most everywhere. The transistor with the lower b-e drop in such pairs will be the only one that does the work... Or it it's close, one will still take say 80% of the current. Still, it doesn't get you any more performance.

[wa2ise]

And here's the schematic: I highlighted the "extra" transistors in yellow.

The first IF amp does look like a good circuit, possibly high gain with minimal self oscillation instabilities. They're also using it as an AVC amplifier for the 2nd IF amp.

[Celt]

Maybe they were trying to "polish the pig"...