In message <iuzLQJA55fC3EwjV@ifwtech.demon.co.uk>, Ian White, G3SEK
<G3SEK@ifwtech.demon.co.uk> writes
snip
>The suppressor is wired in series with the tube, but the way it works is
>that its resistive part creates a permanent PARALLEL load impedance for
>the tube at VHF, low enough to make its gain drop below the oscillation
>threshold. If you analyse the circuit in detail, you find that the
>series-to-parallel impedance transformation depends on the stray
>inductance that is causing the VHF resonance. There's the problem: the
>load impedance seen by the tube depends partly on the suppressor
>characteristics BUT ALSO on the stray inductance in the amplifier.
And the suppressor does stuff all at the vhf frequencies where the tune-
C/coil combination looks high impedance.
snip
Steve
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