Bill Coleman wrote:
>
> Working on a homebrew 4-1000 amp. The CN is a piston type (outer sleeve
> feeds below chassis to the grid circuit, inner / adjustable sleeve connected
> to the anodes). Due to space considerations, CN is sitting appx. 4.5" from
> the anodes (centerline to centerline) or appx. 3" from the anodes to the
> outer (grid) sleeve.
>
> I can't get a null... as I reduce CN, feedthru steadily decreases until the
> adjustable cylinder is at the limit of it's travel at minimum C.
Is this a bridge neutralizing circuit, in which the Cn is connected to the
bottom of the grid tuned circuit, which is grounded via a second capacitor? If
so, you can increase the value of this second capacitor, which will have the
effect of requiring Cn to be larger.
If you are trying to use a triode-type neutralizing circuit (i.e., a balanced
grid circuit with the Cn connected to the opposite side from the grid and the
center grounded) then no wonder this doesn't work! The Cn required for a
tetrode with this circuit would be too small to be practically realized.
73,
Vic, K2VCO
Fresno CA
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