On Sat, 13 Sep 1997 23:39:46 -0700 "Ron Angle (AB6ZX)" <dom@shocking.com>
writes:
>My ancient 4-400 GG homebrew amp is nearly ready for HV tests after
>extensive modification and checkout. Am running the filaments tonight
>for the first extended test with the blower in place. Both 4-400s are
>from RCA and the ages are unknown. One has a bluish/green glow when
>viewed from the top of the tube. The last time I saw such a color was
>on my old 866 rectifiers. I checked the filament voltage on one tube
>(each has its own transformer) and measured 5.0 V. for 120 VAC in.
>
>Fatal flaw?
Possible but not certain. Cook the filament for 24 hours and then run
sufficient idle current so that the plates show color for 30 minutes. Run
plenty of air and be sure to have a suppressor resistor in place in the
B+.
This method has worked for me with everything from 304TL's to 4-1000A's.
Maybe others have a better idea...I'm just following tradition!
GL....Carl KM1H
73....Carl KM1H
>
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>
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