What happened to my awesome Ge transistors 1 year later???

[Rick]

It does seem odd that all these transistors have changed gain seemingly all at once.
Maybe a couple of ideas though - old Ge trannies like these,  could,  I'm sure be damaged
by environmental conditions (esp. heat, humidity, and just age). If the first batch of 25 or so
are still good and not the last batch then you have to figure out what has gone on differently
with each batch. And how about leakage? Correct me if I'm wrong, but nobody seems to have
touched on this subject here. If they have become leaky for whatever reason, they will read
higher gain than they really are. I'm sure you've already built the RG leakage tester, so my
last question is ...did you use the same meter to test all of the transistors? I know this sounds
improbable, but I had a wonky meter like this once. Anyway -good luck with it all   ...Rick

[mac]

ER .... what happened to my post with the hfe/comparison list !!!
Did I say something bad .. ??

MM   

what happened to my post also??

mac

[mac]

hFE is a fuction of kT, where k is the boltzmann constant and T the temp in kelvin degrees. This is common on eqs. derived using statistical mechanics.
The exact eq. is complicated, but it tells us a couple of things:
1. hFE WILL VARY WITH TEMP.
2. hFE is sensible to temp variations, especially ge.

So, do not panic. This is normal with germaniuns.

One thing that can be done is to measure how a transistor's hFE varies with temp and plot the results. Transistors of the same kind will behave in the same way most likely. This data can be helpful to predict how a ge will react on a circuit if temp changes.

mac

[vanessa]

I could see them jumping up say 10 to 30 hfe or so, but he batch by comparison has doubled in hfe, and quite a few have become unstable.

Not a big change in leakage for the most part. But there are a few now with leakage and in the original tests there were almost none.

Maybe some sort of atmospheric condition? I also live near a military complex; maybe they're doing ray gun testing again and did not warn anybody?

[mac]

I could see them jumping up say 10 to 30 hfe or so, but he batch by comparison has doubled in hfe, and quite a few have become unstable.

Not a big change in leakage for the most part. But there are a few now with leakage and in the original tests there were almost none.

I have a batch of AC187 & AC176. No matter the weather or season, their RG-test voltages, and so their hfe & leakage, fluctuate a lot, close to what you describe. On the other hand, my jap transistors have more stable readings.

Maybe some sort of atmospheric condition? I also live near a military complex; maybe they're doing ray gun testing again and did not warn anybody?

This night, when you switch the lights off, see if your OCs emite a green fluorescent light, jump out of the can and march togheter singing "you're in the army now"... 

mac