Dear LF Group,
Thanks to Brian and Alan for the reports on my test signals on
Saturday night. I was trying out my new field strength measurement
system as a prelude to doing some more antenna tests this winter.
I am now using a W&G SPM-3 level meter, with a tuned ferrite rod
and preamp, which I have re-built to mount on my car. I can now
rotate the antenna and take readings from the driver's seat (not
while in motion though!), which makes field strength measurement
much quicker and easier - I was able to get 30 readings in a couple
of hours at distances between 1 and 8 km. I used a GPS receiver
for position measurement.
Transmitter power was around 150W, giving 2A into my inverted L
which has about 8m effective height. The calculated ERP is
150mW . The field strength measurements gave an average ERP
of 66mW, which is in line with previous measurements.
The cherry picker I was using last winter to support my antenna
has now returned after it's summer migration, so I intend to do
some comparative tests with antennas of different heights, and
also on 73kHz, over the next few months.
Cheers, Jim Moritz
73 de M0BMU
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