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To day my lawn is covered with MOLE MOUNDS of soil. As far
as I can see all you are doing is driving the MOLE population up
NORTH
QRP es Underground earth mode induction seems to achieve
little for big effort !! The local Music Rave can be heard 19 miles
away
in Audio mode using loudspearkers, a 2 Kw amplifier and
an Appliance Operator !!!
G3KEV
----- Original Message -----
Sent: Monday, August 08, 2011 2:45
PM
Subject: LF: 1.095kHz earth mode test at
6km
Today I repeated the earth mode (through the ground) "long
carrier" test of 17.7.11 this time at 1.095kHz rather than 8.760kHz. The same
test location was used in the fens not far from the River Cam. This is now a
very long way from home! As before, I got my XYL to cut the carrier for
periods of 1 or 2 minutes to positively identify my signal. I need to automate
this so she can continue to do the gardening....
4 different receiving
antenna arrangements were tested, using my low impedance MPF102 tuned preamp
into the PC:
(a) an earth electrode pair parallel with the
road,
(b) an earth electrode pair diagonally across the road,
(c) a
single turn loop in the road, and
(d) a 30t 80cm diameter loop at the edge
of the road.
Best results were with (a) and (d). With (b)
there was no detectable.
At 1.095kHz the signal was again around
10dB S/N in 11mHz bandwidth on (a) and (d) and marginally weaker on (c). This
is a similar result to 8.76kHz although I was expecting the signal to be
stronger at this lower frequency. I'm now tempted to do an earth mode
test at a higher frequency, possibly 17.52kHz which I can still see
with Spectran and Spectrum Laboratory and I can derive with my 4060 divider
circuit. Using earth mode I believe I'll still be legal as very little
radiated signal can be present.
The image attached shows the signal
with the RX earth electrodes parallel to the road, i.e. set-up (a), at a
distance of 6km from the home QTH where the TX was running 5W into 20m spaced
earth electrodes.
73s
Roger G3XBM
--
http://g3xbm-qrp.blogspot.com/
http://www.g3xbm.co.uk
http://www.youtube.com/user/g3xbm
https://sites.google.com/site/sub9khz/
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