[Milsurplus] Re: Germanium diodes

[J Forster]

Take a look here:

http://en.wikipedia.org/wiki/Diode

As to failure modes in early diodes, there could be bond deterioration which would
primarily alter the forward conduction properties, or die contamination which could
impact the reverse characteristics. You really need to do a V-I plot to check them
or try a substitution.

A V-I plot is almost trivial to do if you have even the most minimal X-Y scope and
a couple of resistors and some kind of an AC source, like a small filament
transformer.

Best,
-John





Brooke Clarke wrote:

> Hi:
>
> I question if the Germanium material was a problem on hot summer days or if it
> was the circuit design.  I seem to remember a college class where we designed
> amplifier stages using Germanium, Silicon and tubes.  In order to maintain the
> operation point (Ic & Vc) over temperature required strong feedback on the
> Germanium.  With no feedback the Germanium would saturate or open (forget
> which), but with proper design worked fine.
>
> For a common emitter amp the feed back is a resistor in series with the emitter
> and bypassed by a cap.  That stablizes the Ic, Vc over temperature.
>
> --
> Have Fun,
>
> Brooke Clarke