Re: AW: LF: VLF TX experiments_short report

[Roger Lapthorn <rogerlapthorn@gmail.com>]

Stefan,

If I understand correctly, DF8ZR was listening for your 8.9kHz signal but did not receive you. Is this correct?

73s
Roger G3XBM

2010/3/4 Alexander S. Yurkov <fitec@omskcity.com>

On Tue, 2 Mar 2010, [iso-8859-1] Stefan SchДfer wrote:
>
> Yesterday the wind was suitable and the sun was out :-) So i was on the hill
> and did the first test. I even had an oscilloscope there to measure the
> antenna voltage and current waveforms. Some photos of the arrangement
> will be shown on my site at qrz.com in some days (sri, have forgotten
> cable between camera and PC...)
> I just had 1,6kVrms on the wire. That is 23dB less than calculated but it
> was a first test. So, the ERP was just 1/200. Additionally i have
> forgotten a part of the ground radial wich increased the earth
> resistance. Bernd/DF8ZR received in a distance of abt 16km

Anyway this is a new record on 9 kHz:-) Congadulations! Remember, this is
well out of near reactive zone. Thus field decreases as 1/D and if you
increase voltage to 20 kV then distance will be 20:1.6=12.5 times more.
16*12.5=200km. You can see this first test corresponds
well with previous calculations (it SHOULD be abt 16 km with such a
voltage if 20 kV yelds 100-200 km). Factually you got first experimental
insurance of the calculations. Besides real distance may be more then
200km because of ionosphere influence on such distances. All of this is
very interesting.

Regards,
Alexander/RA9MB

-- 

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