I have the intention to replace a germanium diode with a PNP germanium diode in an old amplifier circuit How do I determine the correct R1 and R2 on a 1K trimpot if i chose another germanium transistor with a different voltage drop at Vbe on the circuit displayed?

 

This will make a pretty crappy diode, looking like a 1K resistor when reverse biased?

What does this diode circuit accomplish in the actual circuit?

 

It will be used to replace a 1N2326 diode in an old Fisher receiver The Vbe of the Russian germanium transistor, MP20 is around 0.120 at 2mA

 

It will not work. The like a shunt regulator that can be set anywhere between 1 Si diode drop (about 0.6V) up to the Collector-Emitter breakdown voltage. It cannot give the same forward drop as a germanium diode.

Try a silicon Schottky diode -it will have about the same forward drop as a germanium diode.

 

This is a germanium transistor Putting the collector and base together as the cathode, and the emitter as the anode , give a reading of 0.120 mV @ 2 Ma

Isn't the circuit , called a, "rubber diode"?

 

Then don't bother with the pot. Just connect the bast to the collector -that gives you a very nice germanium diode, unless you need to have it adjustable for some reason...

 

I wish to be able to adjust it for biasing purposes