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Message-ID: <001901c64ed5$dde7e2c0$fc687ad5@w4o8m9>
From: "James Moritz" <james.moritz@btopenworld.com>
To: <rsgb_lf_group@blacksheep.org>
References: <002101c64ac4$2f109860$2102000a@ibm> <8bf118410603190722u455ba0f7q@mail.gmail.com> <000d01c64df6$8e8aea40$2102000a@ibm>
Date: Thu, 23 Mar 2006 23:59:48 -0000
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Subject: LF: Re: portable DX-pedition antenna?
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Dear Dick, LF Group,

I used three 10m telescopic fibreglass "fishing poles" to set up an inverted
L 136kHz antenna for an expedition to Puckeridge some years ago. The
inverted L had about 40m horizontal section, with a single wire, and with
about 300W I had many CW contacts up to 1000km or so, mostly during daylight
(I didn't have the gear to do portable QRSS at that time). The most
effective ground I tried was 4 x 1m ground rods, driven into the ground near
the antenna downlead. This system achieved an ERP around 0.15W in a good
open field location.

The main difficulty with the fishing poles is that they are very flexible -
I had to use nylon monofilament guys at the ends of the horizontal span, in
order  to keep the poles reasonably vertical. I used about 4mH loading coil
inductance, wound on 100mm PVC tubing, in a plastic dustbin to tune the
antenna. I had no problems at 300W, but later experience has shown that
corona will be a problem with this short an antenna wire and 1kW TX power.
The best way to avoid this would be to reduce the voltage by having a longer
antenna, probably 80m or more would be OK, but this would need more poles to
support it.

I missed LX1PD last time around, so would certainly be pleased to work you
in LX!

Cheers, Jim Moritz
73 de M0BMU

----- Original Message -----
From: Dick <knaap159@zonnet.nl>
To: <rsgb_lf_group@blacksheep.org>
Sent: Wednesday, March 22, 2006 9:20 PM
Subject: LF: portable DX-pedition antenna?


> Any suggestions for a DX-pedition antenna which is easy to built up,
> and as efficient as possible?
> Should be capable of withstanding 1kW.
>
> 73
>
> Dick, PA4VHF (LX/PA6Z..........)
>
>
>
>
>