Re: LF: My first tests below 9 kHz

[Roger Lapthorn <rogerlapthorn@gmail.com>]

Horst,

You may be interested in my web page about amateur communications below 10kHz. Have you tried grounded electrode pairs and "earth mode" through-the-ground conduction/induction communications? Attenuation is inversely proportional to distance cubed (near field) so more power will help a great deal. I have yet to repeat my own experiments made some years ago, but this time with a mode like WSPR or QRSS, but I suspect that  even with just a few watts my range would be considerably further than my 0.3kms.

See http://sites.google.com/site/g3xbmqrp/Home/10khz and do look at the attached .pdf paper (see bottom of the web page) on the subject written some years ago by G0AKN (now a silent key).

73s
Roger G3XBM

On 20 February 2010 16:39, Horst Stöcker <horst.stoecker@web.de> wrote:

Hello,

some years before, some experimental licences for ham radio below 9 kHz were issued in germany. Meanwhile this frequency range is free as the Bundesnetzagentur has confirmed last year.

Transmitter is an Präcitronic GF62 Level Generator actually at 8,79 kHz. PA is an old homebrew NF-Amplifier with 2x 2N3055 and about 40 Watt at 4 Ohm into a 100V ELA transformer. Antenna is a T-Antenne of 10m with 20m top capacity and poor ground.

Receiver is a portable sferics RX that I built some years before (AATIS). Unfortunately its whip antenne is highly influenced by trees and houses.

The fact that I can hear (!) my beacon in normal CW up to 100m in an city environment with a highly unmatched antenna makes me believe, that in a better environment and with a matched antenne and with help of ARGO one can make tests over longer distances. But even from my QTH in the city the ODX ;-)) surely can be improved.

The mean problem now ist how to match the antenna . . . - or using ground antennas vor TX, RX or both.

vy73 Horst
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