Germanium investigations

Yeah, I've got an icecream bucket full of them someplace. Haven't looked at them since the sixties. Here, have a geranium:

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RCA vintage datasheet with typical amplifiers schematics examples
 

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The first amplifier in my dorm room system at school was an Electro-Voice 1144 that used a class B solution vaguely similar to the one in the RCA data sheet with drive transformer/phase splitter and output coupling capacitor. The power amp used only 3 devices, a silicon front end driving the phase splitter transformer in Class A mode, and two germanium output devices. I got it completely busted, and had to replace all the power amp transistors with HEP equivalents for the inputs, and for the outputs, Ge samples that I begged from Bendix (a lot of players in the transistor markets in those days). It never was a stellar performer. and I ended up gutting the insides totally and replacing them with my own design - it sounded a lot better after that...

The preamp and tone control section used 3 transistor per channel - minimalist design. Here's the manual:

https://www.electrovoice.com/binary/EV 1144A Service Data.pdf
 
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..Curves soon.
Any investigations news ?
Peak tool max V / A range are ok for small signal but too low for the big Ge power transistors ?

The first amplifier in my dorm room system at school was an Electro-Voice 1144 that used a class B solution..

I can play music with vintage Dual receiver, have fews honesty watt's in class B :D
Hi-fi mainstream product example from that time, Ge AC180| AC181 push-pull stage.
The sound quality is surprisingly nice and relax..
Pure Class A amplifiers with great components build PSU, big heatsinks are practically unknow , even today in the year 2020
 

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Many know that my exploits with vacuum tubes date back to a pre-teen kid in the 60's that got tubes, transformers and other parts from the trash to make guitar and HiFi amps. I also got discarded car radios from a local auto junkyard. If it didn't work, they tossed it. The radios from the late 50's usually had 4 or 5 tubes that ran directly from the 12 volt car battery and one big fat (TO-36) germanium transistor on the back driving an output transformer in a class A SE design. There were several different kinds. The number 2N174 comes to mind, but there was a silver colored Delco branded part that was the hardest to blow up.

that used a class B solution vaguely similar to the one in the RCA data sheet with drive transformer/phase splitter and output coupling capacitor.

The common transistor used in the germanium totem pole circuit was the 2N2147. It was in everything from Heathkit stereos to Acoustic guitar amps. The circuit design comes from the RCA transistor manual.

I wound my own driver transformers and used the circuit for everything from 10 watt guitar amps with car radio transistors to a monster amp that put out over 1 KW from 24 X 2N3773's.

I found one of my old amps with 6 X "2n3055's" when I was moving out of Florida. I built it in high school (1969) which explains my crude construction skills. It made 200 to 300 watts into a 4 ohm load on a B+ of about 100 volts. The measurements were made with a Simpson 260 and a scope, hence the large uncertainty factor.
 

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Germanium DUT circuit ( small signal )
 

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Somewhere in my basement I have a motley selection of Germanium power devices, in a mixture of TO-3 and TO-36 packages. Some are made by Bendix, some Mototrola, and I have a few by Lansdale (ever hear of them?) Sadly, I don't have any by Oliver Germanium (Germanium Power Devices). He used to advertise in all the trade mags during the 80's, and manufactured transistors and honkin' stud mount Ge power rectifiers.

When I have the time (not at present), I'll try to figure out a way of giving some of that Germanium gainful employment. I haven't seen them or touched them in years, but I know they're still down there somewhere. I also have a selection of small signal devices ripped out of transistor radios, probably alloy construction. Those have a far less distinguished pedigree, and quite a few of them probably don't even have part numbers on them. I even have some micas and sil pads for the TO-36 packages, due more to packrat zeal than any organized planning on my part. Biasing up some of the big boys for Class A operation would be a challenge - I'm used to the relatively forgiving nature of Silicon. Thermal runaway with Ge is probably a lot easier to encounter.
 
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