TSSP: List Archives

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.