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Re: LF: coil screening

To: [email protected]
Subject: Re: LF: coil screening
From: "Rye Gewalt" <[email protected]>
Date: Sun, 14 Jan 2001 15:26:54 -0500
References: <002101c07e63$b23a4840$83b501d5@cambridge>
Reply-to: [email protected]
Sender: <[email protected]>
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, [email protected]
73 de Lech, G3KAU



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