[Amps] 8877 Q's

[John T. M. Lyles]

Mark
Most of what you ask should really be asked of the manufacturer. They 
can direct you for industrial applications where you need to switch 
on and off. This is done in many types of processes, but most leave 
the heater lit. There is an area called black heat, which the 
thoriated tungsten filament tubes can operate. However, 8877 is not 
such a device.

>
>1). Does this 50% periodic filament voltage reduction stresses the tube?

Probably not if occassionally but doing it periodically is 
mechanically flexing the heater and lead/seals. This has to shorten 
life over the long term. Ask CPI how much.

>2). What is the recovery time from 50% to 100% caloric output of the
>filament (for a step up voltage)?

I would ask the engineers at CPI/Eimac. Ask for the application 
engineer for industrial tubes, might be John Button. (650) 592 1221.

>3). What happens, if by accident, HV and DRIVE is applied while the filament
>is still ramping up?

BAD THING. You WILL shorten the life of an 8877 if you apply HV and 
drive without the cathode being up to proper temperature.


>Mark
>PS ... Interesting work in your lab :) it remainds me of the times I was
>having fun in Toulouse, F. :)
>You would'n be there by any chance ? :)

No, in New Mexico at National Lab.
Take care and 73

John Lyles
K5PRO


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