[Amps] GU74B's

[Bill, W6WRT]

ORIGINAL MESSAGE:

On Mon, 24 Aug 2009 21:48:37 -0700, "Dave Hachadorian" <K6LL at ARRL.net> wrote:

>I have a commercial amp that uses a pair of GU74B's 
>(4cx800a's).  Due to a recent cable failure in the filament 
>circuit, there was no filament voltage, but plate voltage, 
>screen voltage and RF drive were applied.  After I get the 
>filament cable problem fixed, can I expect the tubes to have 
>survived?
>
>
>Dave Hachadorian, K6LL
>Yuma, AZ
REPLY:

Yes, the tubes will be fine. Tubes can be damaged by operating them with the
filament voltage on the low side, but with no filament V at all, no harm will be
done.

73, Bill W6WRT