Noisy Hackers!

[Trumpetrousers]

Always a good rule if you want to minimise amplifier noise is use quality low noise resistors in first stage esp. if of high value or carrying current - I would have gone straight to R1 and R2....but I can say that now can't I...?

Many early transistors are failing now, esp certain types like the lockfit. Going noisy or intermittent or failing altogether. Funny thing is the Soviet transistors of same vintage seem to be bullet proof in comparison, at any rate the ones I have come across - and you can still buy them quite cheaply. The UFO and bowler hat type are just cool as well. (Germanium and silicon).

Martin

[BusyBee]

Many early transistors are failing now, esp certain types like the lockfit. Going noisy or intermittent or failing altogether.  Funny thing is the Soviet transistors of same vintage seem to be bullet proof in comparison, at any rate the ones I have come across - and you can still buy them quite cheaply.

Martin

I have found old Soviet components to be reliable, only having one transistor faulty so far (I have also used quite a number of valves). I do wonder whether, even though their temperature range specifications etc may be similar to UK / US and possible temperature variations the same their approach may be to expect far greater misuse and variations than in the west. I know with the Russian multimeter that I have had for years has had stress that I have not seen AVO's survive and still keeps going.

Tracy

[Mike Watterson]

The lockfits seem to be mechanical stress issues, poor assembly to PCBs.
AF117 etc, too much tin plate inside can.
I've opened Soviet Ge and they looked like silicon planar construction inside. Not point, metal alloy etc. No internal gel like OC glass tube or AF117. I don't think tinned inside either. They are really Germanium going by characteristics.
The Soviet ones are not usually the same vintage, but 10 to 20 years younger. They were still using Ge transistors when the West was entirely using silicon.

[Terry]

Yes, the trouble with Lockfits are entirely down to packaging problems and, when they were introduced they weren't really 'new'.

The first Lockfits, the BC147, 8 & 9 for example, were simply repackaged BC107, 8 & 9s - which are still going strong.

The 'tin whisker' problem which has affected so many transistors such as the AF117 and all other types in the same packaging has even attracted the attention of NASA - see here.

[Kalee20]

It's ironic that the Lockfit encapsulation, which has a much bigger blob of epoxy, seems less reliable than the little TO92.

Luckily, I have nothing with Lockfits in - I only used one once, and that was in a piece of equipment which would have been scrapped years ago.