From: John Rabson <[email protected]>
Subject: Re: LF: RE: Who needs antennas! - success with ground electrodes on 500kHz
To: [email protected]
Date: Wednesday, June 16, 2010, 4:11 PM

Some years ago, the Cave Radio & Electronics Group was conducting tests on 87 kHz between surface and underground at Roger Kirk Cave near Ribblehead viaduct in Yorkshire. After we had finished the tests I tuned the surface receiver up to 136 and got very good signals from EI0CF. Unfortunately there was no mobile phone service at the site so we could not let him know immediately. We did send him a QSL card.

 73

John F5VLF/G3PAI

 

On 16 Jun 2010, at 21:51CEST, Roger Lapthorn wrote:

Correction - I'm also copying PE1GRL at -18dB S/N using the earth electrode set-up!

73s
Roger G3XBM

On 16 June 2010 20:43, Dave G3WCB <[email protected]> wrote:

That's pretty amazing. You must have really bad soil conductivity. Did you try receiving on the earth-loop antenna?

 

Would the technique work on 137 kHz, I wonder.

 

73, Dave G3WCB IO91RM, nr Windsor, S.E. England

-----Original Message-----
From: [email protected] [mailto:[email protected]]On Behalf Of Roger Lapthorn
Sent: 16 June 2010 20:11
To: [email protected]
Subject: LF: Who needs antennas! - success with ground electrodes on 500kHz

Well, I'm amazed.

This evening I connected my 500kHz transverter straight to the two connections of my sub-9kHz grounded electrodes and TXed WSPR. No attempt was made to match anything on the assumption that the two electrodes system looked not too far from 50 ohms resistive as measured between 1-9kHz.. Pout from the IRF510 is around 5W. What happened?

Three people copied me - M0BMU, G7NKS and M0JXM with reports between -21 and -28dB S/N. The wire to the furtherest ground rod is at most 20m long and most of the way it is 1.5m above ground. Once again, this must be acting as a pretty effective loop mostly within the ground.  Screen grab of the WSPR log attached.

So, if you live on clunchy chalk soils like me then don't worry too much about big antennas, :-)

73s
Roger G3XBM

--
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http://www.g3xbm.co.uk
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G3XBM    GQRP 1678      ISWL G11088

--
http://g3xbm-qrp.blogspot.com/
http://www.g3xbm.co.uk
http://www.youtube.com/user/g3xbm
G3XBM    GQRP 1678      ISWL G11088