Message-ID: <3A620B8E.292E12C5@sitestar.net>
Date: Sun, 14 Jan 2001 15:26:54 -0500
From: "Rye Gewalt" <ryeg@sitestar.net>
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To: rsgb_lf_group@blacksheep.org
Subject: Re: LF: coil screening
References: <002101c07e63$b23a4840$83b501d5@cambridge>
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I wonder it they might have been concerned about outside conditions effecting
their very hiQ coils  (things like rain and/or snow on the roof etc.) and may
have decided to live with the loss of radiation in exchange for stability of
the matching mechanism.

Or maybe the matching system also functioned as a filter to keep their
harmonics under control and they didn't want them getting out of the tuning
shed.

Or stock in a copper screening firm?

Rye K9LCJ

=========

Lech Laszkiewicz wrote:

> I wonder why a very highly professional designers of the Decca system went
> to the expense and complexity of copper sheet screening of the interior of
> their complete buildings containing the antenna tunung/loading coils.  They
> seem to have obtained considerable advantages doing so, inspite of the
> dissertation of a certain homegrown "Guru". Could it be that the measuring
> systems and instruments they used were all wrong?
> Having a mildish dose of a flu like bug and not being allocated a frequency
> I decided to stay in RX  mode. The first night my receiver was overpowered
> by enormous signals from OK, I phoned Derek G3GRO who is languishing on his
> bed of nails in the local hospital and relayed to him via the twisted pair
> the crystal clear sigs from the OK1FIG and his father, OK1ARN.
> Derek had to be restrained by the nurses, he was ready to run to his TX on
> his brand new knee. He is improving and will be leaving the hospital this
> Thursday. I have seen and heard several sigs using Gram and Spectran. Some
> sigs appeared to be almost on the common frequency, much less than 3Hz
> spacing and aural reception was quite amusing, all signals heterodining to
> produce "music of the spheres". I found it very difficult to decide who was
> who but I think I have seen reasonable traces from VE1ZZ, one calling OK1
> FIG and some calling MM0ALM. VE1ZZ appeared to be a bit of his published
> frequency, but it could easily be my own finger trouble.
> I was planning to use my Deeca TX. giving 1.5KW out with a 67v/50amps PSU
> from the club with the big antenna but didn't feel up to it.
> At home, the RF power melted an expensive teflon feed through insulator
> sparking to a metal frame of my glass conservatory fortunately without any
> ill effects on the TX, thanks to the excellent design by those Decca
> magicians. The second night I felt really rotten and went to bed early
> filled with aspirines and liquid medicine derived from the Cognac district
> of France. It appears that I have missed very little.
>
> Crawley club have several brand new, full spec transistors as used in Decca
> TX, (not free but reasonable in batches of four) any Loffer interested pse
> contact G3KAU, QTHR, lechlaski@btinternet.com
> 73 de Lech, G3KAU