Ever noticed these ancient Germanium transistors in TO5/TO39 case...

[eccerr0r]

Anyone ever notice...

Front - left to right
2N1307 - PNP Ge
2N1924 - PNP Ge
2N1305 - PNP Ge
2N3507 - NPN Si
2N5320 - NPN Si

Rear - left to right
Unknown - NPN Ge
2N329A - PNP Si
2N5322 - PNP Si

Why is this weird?

All TO5/TO39's are E B C looking at the bottom when the center pin away from you.

So this means, on the PNP Ge transistors, BASE is hooked up to the canister! Normally base is the high impedance signal (common emitter, emitter follower). I thought Germanium PNP transistors were used as common base as often as Silicon (not that often), hence this being weird ... or is it?

[PeteS in CA]

Re: Ever noticed these ancient Germanium transistors in TO5/TO39 case...

Back in ancient times I used the 2N404A when I was attending De Vry. It was probably obsolete by then, but I think De Vry did some sort of large scale lifetime buy at a really low price for use in their schools. I do not remember whether any of the leads connected to the case.

[eccerr0r]

Re: Ever noticed these ancient Germanium transistors in TO5/TO39 case...

Here you go, for old memory's sake. Well, not the "A" version... and another unmarked "npn" germanium.

The bottom of the 2n404 is epoxy potted or something (or is it glass?) and the pins all appear to be isolated from the case.