TU Rich! I am also thinking about trying neutralization on the amp, Maybe
using a piece of solid copper from a piece of house romex wire (abt 14 or 12
gauge I guess?) and running it parallel to one of the tubes abt 1/2 inch
away??, then to the filament choke and wrap abt 4/5 turns around it in the
same direction that the choke was wound then to ground??? Does that sound
abt right? It "takes off" when I key it and turn the tune cap, then the
grid skies and the plate turns red, even if I un-key it at that time it
"takes off". Phil W2GE
Rich Measures wrote:
> >
> >I need the approximate input impedance for a pair of 572-B's?? I am
> >working on the input matching on an SB-200 to six meters. Abt 60ohms??
> >
> >Still have parasitc oscillation problem and am suspicious abt the plate
> >RF choke, dipmeter shows resonance at 52 (MHz)??? Any ideas?? ......
> >
> ... put a thin coat of urethane varnish on wire to hold in place, when
> dry, remove enough turns to move resonance above 60MHz. // At VHF, I
> would not try to use VHF suppressors.
> .
> - later, Phil
>
> Rich...
>
> R. L. Measures, 805-386-3734, AG6K, www.vcnet.com/measures
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