>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?
>
Yes. A leaky glass-to-metal seal. Kaputsville.
Rich---
R. L. Measures, 805-386-3734, AG6K
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