From: Paul
Date: Wed, 16 May 2001 11:03:14 +0100
Subject: Re: [TSSP] Multimode CW excitation
Malcolm Watts wrote: > The two modes do not always reinforce though. they go through a cycle > which causes a peak coincidence at one point, and a cancellation at > another on a regular basis. Hence the amplitude modulation. Am I > reading your suggestion correctly? Yes, I think so. I'm suggesting putting a two-tone (ie DSBSC) CW feed into the coil base, after having first made the coil resonate at both component frequencies by coupling in a freewheeling primary resonator, thus obtaining a factor sqrt(2) increase in peak volts, due to the power compression of the beat envelope. This in addition to the usual CW burst-mode power compression. > > Then suppose we add a second 'primary' resonator... by which I mean sharing the drive power over multiple frequencies, so that from time to time they will all come together in phase to create a substantial peak. Sort of a half-way house between the trad coil and the CW coil. Not really a serious suggestion unless a way can be found to generate the multi-tone signal which doesn't involve the driver also seeing a mega current pulse from time to time. While we're on the subject, the traditional use of a two-tone test signal is to measure distortion on comms links, eg RF linear amps, etc. Maybe a two-tone test can be devised to measure the amount of non-linearity caused by brush discharges. Cheers, -- Paul Nicholson, Manchester, UK. --
Maintainer Paul Nicholson, paul@abelian.demon.co.uk.