Message-ID: <3AF5BC00.EEF6A5E@alg.demon.co.uk>
Date: Sun, 06 May 2001 22:02:56 +0100
From: "Steve Rawlings" <steve@alg.demon.co.uk>
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To: "LF Group" <rsgb_lf_group@blacksheep.org>
Subject: LF: Measurement of antenna current
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Hi All,

Today, I made some more antenna current measurements on my 12 m
vertical (and my shiny new loading coil), using a thermocouple
meter.

At resonance, the current into the base of the loading coil, was
2.2 A.  But when measuring the current into the antenna at the
hot end of the coil, the meter only indicated 1.8 A.  I had
expected the reading to be the same at both ends of the coil. 

The loading coil has many more turns than is required to resonate
the 12 m vertical, so the connection to the antenna uses a tap
which is several turns down from the top of the coil.  I've been
thinking that the excess turns at the top of the coil may be
causing the difference in current readings.  (This may sound
silly, but in my mind's eye, I can sort of picture some of the
current in the coil going into the capacitance of the antenna;
and some current going into the capacitance of the unused turns.) 

Before I try removing the excess turns, I'd like to know whether
the current should indeed be the same at both ends of the loading
coil.  Can anyone help?

Regards to all,
Steve GW4ALG