On Sat, 19 Feb 2005 14:28:50 +0000 (GMT), "Dave Plowman (News)"
wrote:

In article ,
Don Pearce wrote:
Even the small signal devices were fragile. Remember those little blue
anodized clothes pegs you clipped on the leads before you soldered
them? I'm not sure whether that was a bit of overkill or not, - or
perhaps just testimony to the horrible quality of soldering irons of
the day and Ersin multicore solder.

Well, perhaps the standard amateur soldering iron was the Solon 25 watt -
or an early Antex 15 watt. And I'll bet they both reached pretty high
temperatures. I've still got a Solon somewhere and could check.

Very hot, I think. I remember mine - the tip used to end up hollow
after an hour or so of use as the copper got leached out. And that was
even with the solder with a bit of added copper to prevent that very
thing.

I made a heatsink using a standard crock clip with copper wire soldered
into the jaws and copper plates to the 'handles' :-)

Probably worked better than the "real" thing.

d

Pearce Consulting
http://www.pearce.uk.com

"Don Pearce" wrote in message

On Thu, 17 Feb 2005 22:48:50 -0000, "Malcolm Stewart"
wrote:

"Eiron" wrote in message
...

I bet the transistors are germanium too.
--
Eiron.

... and what's wrong with germanium?

Thermal runaway is just the first thing that comes to mind.

Not a problem with proper biasing.

The one totally unmanagable problem germanium transistors had was the
inability to survive at temperatures that a silicon transistor could handle
with acceptable reliability.

"John Phillips" wrote in message

In article , Jim Lesurf wrote:
You've reminded me that I still have some 'fag packets' of very old
Newmarket transistors and some other antique devices in a drawer at
work. Perhaps I should put pictures on a webpage or donate them to a
museum. :-)

When I was last in Munich, with a half-day to spare, I visited the
Deutsches Museum. The telecommunications, computers and
microelectronics galleries came as something of a shock. It was
chilling to discover *in a museum* semiconductor devices I had worked
with as a young hobbyist, computers I had used as a student, and kit
I had seen brought to market as state-of-the-art during my early
career.

The model aircraft gallery was a far more pleasant piece of nostalgia
since it was one of my other hobbies before going to university.

Recommended if you find yourself in Munich. However I think they may
already have the sort of exhibits you offer.

Agreed. I haven't been at the Deutsches Museum for over 30 years, but I
still remember my day there and smile.

"Jim Lesurf" wrote in message


My only real experience with Ge devices has been with things like
AL102's in sets made back in the 1960's. These seemed to show
initially high rates of failures as you'd expect. Indeed, the term
'firecrackers' might be relevant here... :-)

I designed a phono preamp based on 2N404 ge switching transistors as a
junior engineering project. It outperformed the PAT 4 and remained
operational for a long time.

In article , Arny Krueger
wrote:
"Jim Lesurf" wrote in message


My only real experience with Ge devices has been with things like
AL102's in sets made back in the 1960's. These seemed to show
initially high rates of failures as you'd expect. Indeed, the term
'firecrackers' might be relevant here... :-)

I designed a phono preamp based on 2N404 ge switching transistors as a
junior engineering project. It outperformed the PAT 4 and remained
operational for a long time.

I also still have some (Armstrong) tuners and amps that use Ge devices and
which still work OK. The small signal devices generally seem fine if used
within their limits.

The problem with 'power' devices like the AL102 seems to have been
unreliable thermal/mechanical bonding. Hence in the same conditions of use
some devices would prove reliable, but others out of the same box would
fail quite soon due to variations in manufacture from one device to the
next.

This wasn't really a problem with Ge as such. Indeed, a few decades later I
encountered similar problems with InP Gunn diodes! The problem was that the
makers hadn't then learned how to bond/mount the devices reliably so as to
provide a good thermal path.

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html