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" <dhchurch@lineone.net>
To: <rsgb_lf_group@blacksheep.org>
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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