[Boatanchors] [AMRadio] 4-1000 question

[Paul Baldock]

I discovered the "no drive" currents vary with plate tuning control. 
It turns out that its oscillating up around 100MHz.

This amp was designed for a 3-1000, so maybe I need a different APC 
for a 4-1000

- Paul


At 04:55 PM 11/6/2012, you wrote:
>Based on the replies of been getting, I should have highlighted 30mA
>grid current WITHOUT DRIVE APPLIED.
>
>Thanks
>
>- Paul
>
>At 03:50 PM 11/6/2012, Paul Baldock wrote:
> >I have acquired a LK-2000 linear that uses a 4-1000 in grounded grid,
> >zero bias. B+ is around 3400V. Control Grid and Screen Grid are 
> both grounded.
> >
> >When I go to transmit (no rf applied) the standing plate current is
> >about 140mA which is good. However the Grid Current (Ig1+Ig2) is
> >about 30mA - I would have thought it should be zero but I am not that
> >familiar with using Tetrodes as Triodes.
> >
> >I tried a second tube (they are both pulls) with very similar results.
> >
> >It does not appear to be a metering issue.
> >
> >Is this normal?
> >
> >Thanks
> >
> >- Paul   KW7Y
> >
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