Steve said:
>What we want from the suppressor is low resistance between the anode and
blocking cap/tune C at hf, and high resistance at vhf. Given that
there's a series circuit from the anode through the suppressor, blocking
cap and tune C to ground, looking at the series resistance the
suppressor introduces is the useful way to view it<
This is where I disagree. A higher impedance at VHF between the anode and the
blocking capacitor means that there is more gain at VHF - at least, at the
anode connector. A lower Q means less phase shift (and also lower impedance),
so the phase margin improves. Thus the inductor shunted by a resistor, having
an impedance that tends towards the resistor impedance as the frequency
increases, gives an upper limit to the VHF gain. This improves matters on a
Bode plot.
(I've always had trouble with Nyquist diagrams and normalisation and what it
really means, and exactly what parameters they are at 1 and -1 or wherever it
is they always oscillate, etc...)
73
Peter G3RZP
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