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[AMPS] parasitic suppressors

To: <amps@contesting.com>
Subject: [AMPS] parasitic suppressors
From: amps@txrx.demon.co.uk (Steve Thompson)
Date: Tue, 6 Apr 1999 18:54:57 +0100
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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