Russian power transistors

Thread Starter

Ian0

Joined Aug 7, 2020
3,188
I'm looking for germanium power transistors, to make an audio amplifier.
My data Tabulation of Published data on Soviet Electron Devices suggests that a P217 should be a 60V 7A NPN device, but all the usual Ebay sellers have it listed as PNP. Does anyone know for certain?
I'm looking for NPN and PNP drive transistors, and either NPN and PNP output transistors or just PNP to make a quasi-comp.
Any suggestions?
 

Thread Starter

Ian0

Joined Aug 7, 2020
3,188
Is there a make and model number of the amplifier to search for?
Not as yet - I'll design it according to the parts I can find!
My hare-brained idea was to make a germanium amplifier based on the more recent design work such as Doug Self's and see how good it is.
 

DickCappels

Joined Aug 21, 2008
7,690
They seem cheap enough, generally less than $3 each. You might want to buy just one and check it out yourself. Many of the sellers of electronic components
on ebay don't understand what they are selling.
 

schmitt trigger

Joined Jul 12, 2010
463
Exact what Dick said.
Most Ebay sellers ignore how to interpret the finer technical details.
Some time ago, I actually spotted a listing offering “assorted PPN” transistors.

I like your idea of an “all Germanium” audio amplifier.
It should be the ultimate retro amp.
Please post when done.
 

ronsimpson

Joined Oct 7, 2019
1,454
It has been a while back, I used Germanium power transistors. I remember them being temperature sensitive. Some what leaky and the gain varied from part to part.
 

Thread Starter

Ian0

Joined Aug 7, 2020
3,188
More annoyingly, for a power amplifier, Vbe is fairly random. And they don't like more than 55 degrees C - so a ridiculously sized heatsink will be required.
I often see posts about Germanium being "more linear", but doesn't the physics say it should be just as exponential as silicon?
Perhaps the leakage, or the variable gain somehow prevents it from being exponential!
Anyway, I've ordered some P217G 60V power transistors, and in a week or so I'll see whether the cold-war American spies or the Dutch e-Bay seller got the facts right!
 

Thread Starter

Ian0

Joined Aug 7, 2020
3,188
I've looked at a lot of datasheets, and most Germanium power transistor output stages have a conjugate pole pair just below 20kHz, so it looks rather like I'll be making an oscillator not an amplifier if I'm not careful.
However, I found some power devices with rather higher fT, but I can't find any SPICE models. (I'm currently using Bordodynov's models).
I have datasheets for these devices, so could anyone explain how to modify a SPICE model?

In case anyone is interested, I've attached a handy explanation of Russian transistor part numbers.
 

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