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Date: Tue, 31 Jul 2007 08:00:44 +0100
From: John GM4SLV <gm4slv@sighthound.demon.co.uk>
To: rsgb_lf_group@blacksheep.org
Message-ID: <20070731080044.5a5dbd18@lurcher.twatt.local>
Organization: The Gammy Bird
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Subject: LF: 500 GM Update
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Status: O

Hello LF group,

Just a quick update on things in the far north.

I took down my 500kHz antenna on Friday in preperation for a new
installation in a better location further away from the house. My
neighbour who owns the surrounding croft-land kindly offerred a patch
of damp ground about 50m from the house that can easily be fenced in to
keep sheep away from the antenna & stays. I will have at my disposal a
20m x 15m area of wet ground.

I should be able to fill it with radials and several earth rods. I will
also tie in the adjacent fences into the earth system.

I hope to radically improve the ground efficiency.

For the antenna itself - I received a new Spiderbeam 12m fibreglass
pole yesterday and intend to erect it (possibly not all 12m of it) as a
vertical and to run 4 capacity wires along the top guys for about 4-5m.
It should come out somewhere similar in Rrad as the small top loaded
affair I have been using which seemed to work reasonably, but with much
better grounding it should be more efficient.

My new Mark 2 TX was completed over the weekend too. It uses IRF640 FET
as the PA with a trifilar 9:1 transformer as the drain load. It happily
loafs along at 25W on a supply of 13.8v and can easily produce
well over 70W if I raise the supply volts. I should comfortably be able
to drive the antenna to 100mW ERP!

Hopefully (weather permitting) I'll complete the new antenna
installation over the forthcoming week and be QRV by the weekend.

Regards,

John GM4SLV
IP90GG
Shetland