Ron(UK) wrote in message
...
N_Cook wrote:
As far as heaters are concerned. I went to a lecture by Tony Sale of
Colossus rebuild fame
http://www.codesandciphers.org.uk/lorenz/mk2.htm
About 2,500 valves in this computer.
They power up Colossus each day via a motorised variac.

How many valve failures a year, due to failed heaters in those 2,500,
would
you expect ?
Please reply here

Answer tomorrow

In my field (audio amp repairs) actual valve heater failures are very
rare - Occasionally you see a case where the contact between valve pin
and internal riser is intermittent. I wouldnt like to guess at Colossus,
maybe one or two, possibly none. Of course valves ain't what they use
to be!

Ron

They are all old contemporary valves. I should have said how many failures
for whatever reason in those 2,500 per year ? considering that they are
powered up slowly from cold, to reduce that reason for failure .


--
Diverse Devices, Southampton, England
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