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Re: LF: Re: Screening an LF Loading Coil

To: <[email protected]>
Subject: Re: LF: Re: Screening an LF Loading Coil
From: "Alan Melia" <[email protected]>
Date: Mon, 11 Apr 2016 11:10:46 +0100
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Hi Hugh,mmm that is quite a lot. Thinking of the copper lined tuning huts
Decca and Orfordness I guess the keg should be grounded. ??

Alan
G3NYK
----- Original Message ----- From: "LineOne" <[email protected]>
To: <[email protected]>
Sent: Monday, April 11, 2016 10:32 AM
Subject: Re: LF: Re: Screening an LF Loading Coil


Thank you Alan, the location inside makes your suggested spacing,
suspended and spaced on fibreglass rods. It needs more Tx testing as a few
brief reception reports were about 5dB down but that was probably
"propagation" conditions.

Hugh.

On 10/04/2016 17:04, Alan Melia wrote:
Hi Hugh I think the rule of thumb (or at least the one I use) is that the
lowest turn should be at least half the coil diamter from the screen base
(which if too close will exhibit the properties of a shorted turn) and
the diameter of the screen should be at least twice the diameter of the
coil....more is better, but.......

I think that should be OK with your coil size supported in the middle of
the keg, Hope you had the pleasure of emptying it :-))

Alan
G3NYK

----- Original Message ----- From: "LineOne" <[email protected]>
To: <[email protected]>
Sent: Sunday, April 10, 2016 4:50 PM
Subject: LF: Screening an LF Loading Coil


A few years ago I found an aluminium beer keg which had been used for
mixing cement. As it was damaged it was no good returning it to the
brewery so I have just moved my LF loading coil into it and placed the
assembly outside on a corrugated steel roof. (Having the coil suspended
from the shack ceiling was not a good idea for the long term).

I took the end off the keg, which is 370mm internal diameter, and the
coil is on a 130 mm former, likely to be no more than 160mm diameter
wound. The antenna is predominantly current fed so no voltage larger
than about 3kV is present.

Has anyone tried this and am I likely to lose radiated power by reducing
the Q of the coil, the Tx output voltage and current are just the same?

Hugh, M0DSZ





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