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Date: Sun, 27 Jun 2010 12:50:00 +0200 (CEST)
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From: =?ISO-8859-15?Q?Horst_St=F6cker?= <horst.stoecker@web.de>
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Subject: VLF: New test
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Hell Roger, Dreamers,

yesterday I tried to reproduce Rogers experiments with VLF transmissions=
 over the local gas and water mains.
I connected one wire to the equipotential busbar of my house. The other wi=
re is connected to a 60cm copper rod in about 15m distance in the garden=
 - very similar to Rogers setup. I measured about 180 ohm DC. I tried diff=
erent frequencies below 9kHz with an audio transformer.
The "walk around" reception was very disappointing, just a few meters. No=
 way to receive something walking down the street even 100 meters.
Because of the relatively good ground conductivity here it is not surprisi=
ng that the setup does not work as a ground loop. But I had expectected so=
me induction along the mains like at Rogers QTH.
As I do not assume that gas and water pipes of my house are all isolated=
 from the pipes in the street there is just one explanation: The good grou=
nd conductivity.

After that I tried to reproduce the test with the 100m earth base I did so=
me weeks ago. I could hear my signal (Or was it a false signal.) at about=
 500m. This time also nearly nothing - like at my very first test with an=
 30m earth base in my garden.
I had assumed that after some hot sommer days without rain the ground cond=
uctivity would be lower and the results with my earth antenna would be bet=
ter.
It seems my QTH ist not suitable for earth antenna tests at all.

To verify that I next took my T-antenna (10h20t) and the TV transformer.=
 The result: Still audible signal in 100m distance. So I assume that groun=
d conductivity has not changed very much since my previous tests.

Assuming that the T-antenna would work worse after some hot days without=
 rain I was surprised by that.

To verify that I will leave the busbar supported earth base installed so=
 I can measure any time, especially after the next heavy rain. I know that=
 measuring Ohm DC is not measuring ground counduktivity or even impedance.=
 But it will give a glimpse of how of the influence of weather and humidit=
y at my QTH.

The last test was more for fun. I connected my 2x27m Inverted Vee and the=
 both (13m) Wireman cores to the TV transformer instead of the T-antenna.=
 Dispite of more than the double of wire this works worse. So I found conf=
irmed what I hat learned about T-antennas and top loadings: not as Inverte=
d V.

This tests have shown the limits of what is possible at my home QTH on VLF=
.

The next step will be QRSS tests instead of audible CW.

On our field day 23.-25. July I will test the 800m earth base in JO30ON (E=
rpeler Ley). Distance to Stefans Grabber is 160 km, to Markus 300km. Possi=
bly it will be my first successful far field test.

vy73 Horst DO1KHS/DI2AN.
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