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Old 09-25-2018, 09:54 PM
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LADR LADR is offline
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1956 GE 675 find

Got this GE transistor set for $15 wich I don’t think is bad. This thing uses 9 and 13.5 volt batteries for some reason. Don’t know if it works yet, soon will find out. Made the 13th week of 1956 and is GE’s first transistor radio.
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Last edited by LADR; 09-25-2018 at 09:55 PM. Reason: Typo
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Old 09-26-2018, 09:40 AM
WISCOJIM WISCOJIM is offline
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Quote:
Originally Posted by LADR View Post
This thing uses 9 and 13.5 volt batteries for some reason.
Quote:
The reason why GE had decided to use two separate battery line voltage supplies in its original 1955 design, is that the -4.5 volts was used "only" for the 2N137 1st I.F. PNP transistor emitter "fixed" bias voltage supply and was also used for the radio's AGC (Automatic Gain Control) action. GE had used the -13.5 volts for the rest of the circuitry, including the "self" bias voltage supply from resistors (R12-2700 ohms + R5-2700 ohms + R4-220K ohms) for the base of the 2N137 1st I.F. PNP transistor. And when the radio's circuitry would receive a strong radio signal, the 2N44 audio output PNP transistor will conduct more current flow and thus there would be a greater voltage drop across the supply resistors for the base of the 2N137 1st I.F. PNP transistor. This will cause the base voltage to be less negative, while the separate -4.5 "fixed" bias voltage for the emitter of the 2N137 1st I.F. PNP transistor, will remain more constant. This AGC action will cause the "forward" bias of the base and emitter junctions of the 2N137 1st I.F. PNP transistor to be lowered and thus reducing the Beta (hFE) gain of this transistor, which will lower the overall radio's audio volume output.
Lots more info on this radio here (thanks to Rich Hirsh & ARF): http://antiqueradios.com/forums/view...p?f=4&t=208340

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Old 09-26-2018, 08:45 PM
dieseljeep dieseljeep is offline
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Quote:
Originally Posted by LADR View Post
Got this GE transistor set for $15 wich I donít think is bad. This thing uses 9 and 13.5 volt batteries for some reason. Donít know if it works yet, soon will find out. Made the 13th week of 1956 and is GEís first transistor radio.
My Uncle had one of those when they came out. I was like eleven at the time and thought it was pretty neat.
It used that Burgess XX9 battery that wasn't that readily available at the time. I don't remember the alternate Eveready numbers. They also claimed that the same battery was used in a garage door remote.
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