In message <[email protected]>, g3kev
<[email protected]> writes
Hi All. Was planning to operated from Cookstown/Tyrone (GI) this weekend
but because of the gales forecast it might be impossibe to get the 130
ft antenna erected. The tower is in situ and would probably stand the
gales but getting the antenna configured could be difficult. The antenna
would consist of 3 inv L antennas in parallel each one 130 ft vertical
and each top section 400 ft long. Wire used is 2.5 mm insulated with
suitable marine insulators as required.
They would converge at the bottom and be attached to a base loaded
inductor to resonate at 137 khz. The ground radials consist of 10
lengths of 400 ft 2.5 mm insulated wire and the far end of each one
connected to sheep fencing which runs for miles across the country.
The radials are elevated about 1 metre above ground. The output should
be around 1w erp.
When serious transatlantic tests evolve ie compatibility at each end I
will extend each top loading wire several hundred feet to maximise
efficiency both on tx and rx.
I intend to operate from this qth several times each year wx permitting,
I do not want the tower wrecked in gales or storms. The tower is heavy
duty commercial lattice construction and telescopic and guyed with heavy
marine rope. It is fine when erected but getting it up and wires
attached in gales is another story. Getting it back down in a storm is
even WORSE, the sections will not slide down properly because of the
wind pressure agains the sides. The guys are slack and then it gets VERY
DANGEROUS. You have to experience this to appreciate the hazards.
Maybe a 20 ft pole or a low tree, which most are using on Lf is the
answer and would be safer and forget about DX except for a bit of luck
once in a while.
Would it be worth remembering what Marconi discovered when the gales
ruined his aerials at Cape Cod? That an inverted 'L' aerial has some
gain towards the feed end (?).
Mike
--
M.J.Powell
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