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A Modular AM radio? GE model P-807H

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A Modular AM radio? GE model P-807H Empty A Modular AM radio? GE model P-807H

Post by Ragwire Thu Mar 26, 2015 9:28 pm

This is a GE, model P-807H AM radio from 1964. It only needed a little cleanup, really, and repainting the tuning dial lettering...oh, and a modern 9V battery connector put on it. I have never seen a modular AM radio before now; I suppose it was supposed to make servicing easier. I remember the modular plug-in solid state televisions, but have never seen something as simple as a basic AM receiver that was modularized. The schematic below is not the complete page, but shows the outlines of the three sections. The pin voltages, etc. are given in the service literature, and it also stated that each module should be considered a "part" and replaced as a unit. These are each soldered in with a few pins to the main board. Of course, all the parts are accessible and detailed on the schematic, so one could replace the discrete components instead.

I thought it was unusual. Anyone ever seen anything like this before?

A Modular AM radio? GE model P-807H 1-GE%20P-807H%20Before_zpssn8taa2z

A Modular AM radio? GE model P-807H 2-GE%20P-807H%20Back%20Before_zpsuh8o58hc
A Modular AM radio? GE model P-807H 3-GE%20P-807H%20Chassis_zps4z0ejjfm

Pins are soldered to the main circuit board:
A Modular AM radio? GE model P-807H 4-GE%20P-807H%20Chassis%202%20-%20Copy_zps3zcaw7jp
A Modular AM radio? GE model P-807H P-807H%20Schematic_zpsmaudqocq

All done:
A Modular AM radio? GE model P-807H 5-GE%20P-807H%20After_zps0ifys0b0
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Post by 75X11 Thu Mar 26, 2015 9:40 pm

That was made when hybrid circuit construction was really catching on with commercial 2-way radio manufacturers. I would venture the guess that the modular construction was more to benefit manufacture than servicing. I'd not seen a consumer radio of that vintage assembled in that manner before. That is an interesting radio.
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Post by Ragwire Thu Mar 26, 2015 9:52 pm

75X11 wrote:That was made when hybrid circuit construction was really catching on with commercial 2-way radio manufacturers.  I would venture the guess that the modular construction was more to benefit manufacture than servicing...
That does make more sense, on second thought. I didn't even know it was modular until I bought it and got it home. Glad I got it. Very Happy
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Post by Wildcat445 Thu Mar 26, 2015 9:56 pm

Nice job on a neat radio. Enjoy. Very Happy

WC

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Post by 75X11 Thu Mar 26, 2015 11:08 pm

Circuits like those and the couplate circuits evolved into the integrated circuits of today as their functions became more complex. Your radio gives a view of the beginning of the concept. You can freak the kids out with that. Very Happy
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Post by Ragwire Fri Mar 27, 2015 9:46 am

Thanks fellas.
LOL...ya, the kids think every modern concept is a new concept.
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Post by Bill Cahill Fri Mar 27, 2015 9:53 am

They used to be fairly common. I believe they are from the late fifties., but, I'm not sure...
Fidelity was o. k.., but, not great. The output transistors would occasionally fail. But, I like the style. They came in different colors.

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Post by Ragwire Tue Mar 31, 2015 11:26 am

This particular one is from 1964. Can regular silicon transistors (but PNP) be used to replace the old germanium ones? I always wondered that. I wouldn't know where to get germanium transistors anymore except from another scrap radio.
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Post by Bill Cahill Tue Mar 31, 2015 2:30 pm

We tried that at the shop, and, with few exceptions, didn't work.

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Post by Ragwire Mon Apr 06, 2015 8:07 am

OK...Thanks Bill
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Post by Conelrad Mon Apr 06, 2015 9:34 am

That speaker with the armature motor is a real throwback, too.

Dennis

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Post by Resistance is Futile Mon Apr 06, 2015 10:14 pm

The difference is germanium has a lower junction voltage of around 3/10ths of a volt vs silicon transistors at 6/10ths of a volt. you would have to make some changes in resistors. (Biasing)
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Post by Ragwire Thu Apr 09, 2015 9:04 pm

That might work. The one time I tried it was in the power amplifier stage of a Japanese made tabletop. I did nothing to try rebiasing because the base to emitter voltage was supposed to be close to that. The amp passed audio, but was really weak. The radio was never repaired and I ended up scrapping it for parts.
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