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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