On 2 Nov 2007 at 9:00, John Pumford-Green GM4SLV wrote:
> However, I don't think Dave runs even 25W though, and his antenna, by
> his own admission, is very inefficient due to his sandy soil so he's
> doubly handicapped:-
>
> Low TX power and poor efficiency.
I run around 6W output. My original calculations which was what the
wording on my NOV application were based, was that the maximum power
I would use would be 10W and that my proposed vertical would produce
around 100mW erp. And my objective, as also stated on my NOV
application, was to evaluate the use of 500kHz from a 'typical urban
property'. To that extent I have now evaluated my experiments.
The earth loss, at 150 ohms measured, proved rather higher than the
20 ohms or so that I assumed in those original calculations.
The results I am getting are very much in keeping with my setup and
antenna. Using a vertical antenna with no horizontal section there is
very little high angle radiation. So within the ground wave zone, 100-
150 miles or so, results have been remarkably good and I can have
excellent chats with some of the stations in this area. Because there
is no high angle radiation longer distance stations are hard to work,
much as I experience in using this vertical on 160m. But I would
expect at even further distances, eastern Europe, for instance when
the sky wave is at a low angle, results may be a bit better.
Remember also that any antenna with a horizontal section will radiate
from that section. Theory may say it cancels out due to earth
reflection, but that is only really true if you have a perfect earth.
As for running higher power, that is not really my option. Regardless
of saying that I would not run more than 10W on my NOV surely the
answer is to find ways of lowering the earth resistance to something
more comparable with what others experience rather than just heating
up the garden with virtually all the power. I shall not be doing that
myself, others may see it as an answer.
Since I shall be changing the antenna over to 160m before CQWW at the
end of the month, it is probably fairly academic.
73 Dave G3YMC
http://www.davesergeant.com
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