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The same advice as from others go into the open
countryside away from all pipes and cables and do the job properly.
Set up a transmitter as Stefan does out in the forest and
then try an earth mode antenna and RX at intervals and see how you get
on.
de g3kev
----- Original Message -----
Sent: Thursday, February 03, 2011 2:40
PM
Subject: Re: LF: RE: More earth-mode
tests and a puzzle
Hi Roger,
First, congrats to the 3 km in QRSS-3! This
allows you to do local QSOs :-) What about G6ALB? Has he tried to receive your
transmissions as well? This would allow you both to to a QRSS-3 VLF QSO!! Have
you tried this?
Am 03.02.2011 11:35, schrieb Roger Lapthorn:
What I do NOT understand is why I get ZERO signal pick-up
from G6ALB at 3km with another earth-electrode set-up at the RX end. One of
my ground points is the copper central heating radiator which connects
directly to metal pipes in the road. I know this as I use the same set-up to
launch my own earth-mode signals that can be detected in the roads with a
loop out in the fens >5km away.
...but in your own experiments
you received your signal with the loop and here you want to receive it with
the earth electrodes. This seems to show that it is easier possible to receive
the magnetic field caused by the current flow in the pipes than measuring a
current flow through the soil between your electrodes in your garden (causing
a potential difference between them).
Logic tells me that if Andrew G6ALB is launching his signal
along pipes from his earth electrode pair then I would get strongest signals
by also connecting one ground to the metal pipework at the RX end, but this
is definitely not the case as there is absolutely no signal
detectable in QRSS3 by this method, but at least 20dB S/N with the EFP! Can
someone explain what is going on please as I am very
baffled!
Check if there is a difference in the signal level
and SNR if you disconnect the EFP from the local ground, i.e. use a
battery and a notebook. Go out in the fields with all 3 forms of antennas
(loop, EFP, earth electrodes) to check the difference at an equal distance. If
the noise and a reference signal (e.g. Alphas) stays at the same level but
your 9 kHz signal level is strongly reduced, it may have been supported by the
quasi galvanic coupling to one of the TX antennas legs. This may be the
difference compared to your own transmission. As you've been /p with your RX,
there was no ground connection to the TX!
Go out in the forest, far
away from pipes and cables and install a large (real) earth antenna, pointing
to G6ALB. First you may try to receive G6ALB with the EFP and/or the
loop.
Good luck and fun with your
experiments!
73,Stefan/DK7FC
PS: Which of the 3 antennas gives
you the best SNR of the Alphas? Which one shows the sferics as the dominant
noise source arround 9 kHz? :-) What about mains hum? Will you try to receive
me this weekend? :-) Most probably i'll do the 10th this
sunday!
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