Message-ID: <23184.200101311724@gemini>
From: "James Moritz" <j.r.moritz@herts.ac.uk>
Organization: University of Hertfordshire
To: rsgb_lf_group@blacksheep.org
Date: Wed, 31 Jan 2001 17:28:55 +0000
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Subject: LF: "Flutter" / LOPT cores
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Dear Tom, LF group,

I think Andy must be right about the flutter - myself and G3AQC are 
often within 1 or 2Hz of each other, and the flutter is produced by 
the two signals beating together. I heard something similar when 
EI0CF rang up the other day, and I was able to listen to the signals 
over the phone. The tiny frequency separation is neccessary so 
that the guys on the other side of the pond can bring high-
resolution software to bear on 2 or more signals at the same time, 
but it certainly isn't very helpful when trying to identify signals 
aurally.

The ferrite cores used in TV EHT line output transformers use 
similar materials to the SMPSU transformers - they operate at a 
lower frequency, so some might be more lossy, you will just have 
to try. The type with a metal clip are handy to wind cables round for 
RFI supression, but they are a slightly awkward shape for making a 
transformer with. Make sure you remove any thin plastic film 
spacers from the joining surfaces before using; the 'air gap' is good 
for an energy storage inductor, but not a transformer.

Cheers, Jim Moritz
73 de M0BMU