>Let me start this over.
>
>Typically it is imperative to not apply drive to a grid driven tetrode
>unless anode voltage is applied.
** In grid driven, Class AB1, there is zero grid current and zero
grid-dissipation whether anode V is applied or not. The critical thing
is that screen V not be applied unless anode V is present.
> This is usually accomplished by
>interlocking the T/R switching.
>
>I have a Harris RF-110A which uses a pair of 8122s. When operating, the
>8122s are Class A. However there is no protection against applying grid
>drive at any time (power on / power off / anode on / anode off / filament
>on / filament off) - the input is completely unswitched.
>
>Simple question: Will application of 20 or 30mW of RF damage the tubes
>when they are not "ready" ??
** The rated grid-dissipation is 2w each, so 30mW of drive should be
safe.
>It looks like the 8122s can handle a couple
>watts of grid dissipation each - is this relevant if they are driven when
>not "ready" ?
>
>I can add a drive interlock if necessary - it's going to be a pain -
>though not as much pain as toasting the tubes.
>
>Thanks, Bill
>~~~~~~~~~~~~~~~~
>Bill Coleman N2BC
- R. L. Measures, a.k.a. Rich..., 805.386.3734, AG6K,
www.vcnet.com/measures.
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