You don't bypass the neutralizing cap. You reduce the value of the
bypass cap at the cold end (away from the grid) of the grid tank circuit
so that it will above ground for RF to some extent. You connect one end
of the neutralizing capacitor to that point, the other end to the plate.
This provides out-of-phase RF feedback. The ratio between the 'bypass'
capacitor and the neutralizing capacitor determines the amount of feedback.
You need to look at the ARRL or Bill Orr handbooks. There are circuit
diagrams that make this clear. It's called 'bridge neutralization'.
73,
Vic, 4X6GP/K2VCO
Rehovot, Israel
http://www.qsl.net/k2vco/
On 27 Jul 2015 03:50, Roger wrote:
Sorry, I thought it was clear what I was trying to do. I have four 4x150a
tetrodes in parallel, attempting to make them operate on 50mhz. I'm
confident my DC is stable. Additional information includes, a Pi tuned
input and output. Input and output terminations are quality 50 ohm devices.
Power supply and rf deck are in separate boxes. My problem appears to be
related to instability possibly caused by insufficient or incorrect
neutralization.
It was mentioned that the neutralizing cap needed to be by-passed and
that's something I have not even considered. By-passing anything in the
grid circuit seems contradictory to me.
73, Roger
AI7RR
On Sun, Jul 26, 2015 at 3:56 PM, <donroden@hiwaay.net> wrote:
Quoting Ron Youvan <ka4inm@gmail.com>:
I am trying to find out what you are trying to do.
Me Too Ron,
He has to make the amp DC stable before hooking up the input and output RF
networks. We don't know if that's the case yet.
Don W4DNR
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