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Larry Larry is offline
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First recorded activity by BoatBanter: Jul 2006
Posts: 5,275
Default Ping Larry: Sintered Bronze

Peter Hendra wrote in
:

I don't mind shelling out US$200 if it will provide even a modest gain
in reception or transmission. What is your angle on this?

Given that I do buy it, where is the best place to install it, apart
from permanently below the water line?



If you already have a good earth (ground to the Americans), adding
another one probably will make no difference. I would like the ground
(er, ah earth) cable that connects the HF tuner to the ocean to be
installed with NO SHARP CORNERS in the most direct path available. Make
SMOOTH, not necessarily neat, turns. NEVER make a sharp turn with coax
cable, I don't care how neat it looks. Sharp turns in the earth bus act
like little inductors in series between your tuner and your earth...not
good...raises the impedance of the earth to the tuner.

To show you how futile this is on a sailboat, let me describe the earth
used at an AM broadcast station.....

If we drive a 3 meter ground rod into the ground at the base of the AM
tower, which is the AM stations actual antenna like your backstay
probably is your HF installation, it will work. However, it will not
work "good"....near as "good" as 36 sections of bridge cable arranged out
horizontally, radially, from a big, heavy cable ring at the base of the
tower to hook the transmitter's earth to. It's called a "counterpoise"
and creates an artificial earth in even very poorly conducting soil.

Now, you can, while you're at sea traveling ahead and not backing over
it, create a pseudo copy of this earth with a single wire hooked straight
to the tuner's ground post, thrown directly overboard to trail out in the
ocean behind the boat...straight as you can get it. The longer the
better, but a good length is from 15-35 meters long. DON'T forget to
roll it up as you come into port so it fouls rudder or screw! This dirty
little secret is a MUCH better earth for your HF radio than anything
screwed under the hull. Even hookup wire will work, but a nice old piece
of stainless winch cable with lots of open strands that won't rust makes
a fantastic trailing-earth ground. Try it with and without....doing a
retune on the tuner as it WILL change the feedpoint impedance of your HF
antenna quite drastically, once connected.

No big $$$ outlay is necessary....just an old piece of stainless cable,
tied off to a sturdy handrail post or the base of the backstay below the
bottom insulator is fine. Don't worry about it sinking. If it were
100' STRAIGHT DOWN, which it won't be unless you're becalmed, that would
be BEST! It doesn't need a dragging anchor to attract the really big
fish, either. If you like, you can just trail it out when making HF
calls, then coil it back in to store it. Works great...

Larry W4CSC
--
Geez, a ham letting out his secret weapons...how awful...(c;