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From: "James Moritz" <james.moritz@btopenworld.com>
To: <rsgb_lf_group@blacksheep.org>
References: <000001c8379a$cbf54800$8700a8c0@rtv5f9d8dfdf44>
Date: Thu, 6 Dec 2007 01:53:43 -0000
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Subject: LF: Re: [500] RE: M0BMU/P on 503.8
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Dear Lubos, Mike, Graham, LF Group,

Thanks for the reports - I was doing some antenna tests, as part of the
programme in my Special Research Permit application for 500k. The 1/2-space
DFCW setting is a bit difficult to read on the screen, but is convenient for
field strength measurement since there are only short gaps in the carrier.

Briefly, the idea was to set up a replica of my home QTH antenna in an "open
field" location, and compare the performance with the original antenna,
which is surrounded by trees, etc. in order to get some figures for the
effect of the site on antenna performance.  The /P location is near Newgate
Street, a village about 4km east of my home QTH in Hertfordshire, and really
is an open field, belonging to one of my relatives. Actually, as the rain
keeps coming down, it is starting to remind me more and more of the pictures
of the Scarborough reef expedition in Radcom a little while ago!

A quick look at the figures from FS measurements and loss resistance
measurements looks quite interesting so far. The calculated ERP seems to be
close to the measured figure, so not much "site loss", and the loss
resistance at 500k is about 1/3 of that of the original antenna - only 8.5
ohms. This means the "open field" antenna is about 6 times as efficient as
my home QTH antenna at 500k, although the antennas themselves are nearly
identical.

Weather/circumstances/Murphy permitting, I hope to test the same antenna on
136k tomorrow evening, and will hopefully have some more detailed results by
the weekend.

Cheers, Jim Moritz
73 de M0BMU

----- Original Message -----
From: "Lubomír Bobalík" <lubomir.bobalik@rtv5.cz>
To: <rsgb_lf_group@blacksheep.org>
Sent: Wednesday, December 05, 2007 11:58 PM
Subject: LF: [500] RE: M0BMU/P on 503.8


>
> Hallo Mike and All!
> I captured DFCW signal on 503800kHz as you can see on the snapshot. The
> signal is growing stronger.
>
> 73 from Lubos, OK2BVG, JN88KS
>