Amps
[Top] [All Lists]

Re: [Amps] Suppressors

To: Steve Thompson <g8gsq@eltac.co.uk>, amps@contesting.com
Subject: Re: [Amps] Suppressors
From: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Reply-to: g3rzp@g3rzp.wanadoo.co.uk
Date: Wed, 30 Aug 2006 14:57:04 +0200 (CEST)
List-post: <mailto:amps@contesting.com>
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
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps

<Prev in Thread] Current Thread [Next in Thread>