local demolition of SAGE building

[lee davison]

> And as found with Colossus, it's power cycling that really
> kills them, so keep that to a minimum and they tend to last
> pretty well.

The fail rate can be reduced significantly by bringing the
filament supply up slowly, over a couple of minutes, and then
applying the bias supplies for a period, the longer the better,
before the HT is applied.

It's not unusual to see lifetimes of 150,000+ hours on
transmitter valves using these techniques and that's on valves
power cycled a few times each day.

Lee.









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