russian ge-transistors

[rnfr]

Hi

all russian ge's i have measured and read about have had extremely tight tolerances.

That is interesting.  It is very unusual to get tight tolerances in Ge devices - even the best of them.  Some of that is due to intrinsic issues with Germanium.  For example, hFE and leakage are VERY temperature dependent.  You can try heat sinking to the max and building in temperature-dependent biasing (e.g. negative feedback to prevent thermal runaway).  But Germanium devices are simply more temperature sensitive than Silicon ones due to its position in the periodic table.  Silicon junctions hold their characteristics until quite hot and don't melt until 150 C (or more).  However, Ge junctions are drifting this way and that at 40 and 50 C (try putting one in RG Keen's tester and put your fingers on it and off it, and watch the readings dance to and fro !)

This is not to say that I don't like the Russian Ge devices.  I think both the 308s and the 313s are terrific!  But I've posted before that they have a considerable range of hFE.  That can be a good thing, too !

cheers
Brett

i'm aware that they are dependent on temperature, all ge's are right?  maybe i just got a good batch, but i found that once they were allowed to get down to room temperature, they were not as widely varied as other transistors (ac128's for example) were reported to be.