On Thu, 05 Aug 2004 07:58:05 -0400, Jerry Peters wrote:

I have been researching SSB installation issues and am left with a
couple of questions.

First, antenna installation. I intent to use a long wire through a
tuner to operate on HF. I intend to use an insulated shroud (I have a
cat with no backstay) with a short feed from the tuner. I have always
believed that the feed wire should be seaparated from the rigging before
it reaches the connection point to reduce capacitive reactance. I have
accomplished this in the past with 2" spacers holding the wire off of
the shroud until it reached the connection point. Recently, I read a
credible opinion that separation of an inch or two is irrelevant at high
frequencies because to eliminate all capacitive reactance the
seaparation would have to be meters. The capacitive reactance that does
exist can be accomodated with the tuner. If this is true I would prefer
to directly attach a long insulated wire to the shroud - perhaps tape it
over a 25 foot length. It would be out of the way, safe from rf burn
risk and would not require the installation of rigging isolators which
introduce mechanical weakness and expense.

My second set of questions relate to ground plane/counterpoise
installation but I'll hold of on those quetions for the moment.

Thanks for your help.


You can attach your feed line to the chain plate, down below, out of salt
water harm's way.

Some will advise you to attach a jumper wire around the rigging screw
(turn buckle). Try it first without a jumper. Try it with a temporary
jumper and see if you notice a difference. If so, install a permanent
jumper.

Remember your antenna starts where the tuner ends. The feed line from
your tuner to the shroud, vertical wire, insulated back stay, 23 foot
whip, or what ever you are loading up, is part of the antenna.

The reality is all the metal shrouds, booms, masts, 12 volt wiring, etc,
become hot with RF. Yes there will be capacitive coupling of your feed
line to the shroud below the insulator. You can measure these currents
with a clip on RF current meter. MFJ sells such a meter.

Besides, capacitive coupling to any metal on your vessel just makes that
piece of metal part of your antenna system. Any SSB installation on a
fiber glass yacht is a compromise. Regardless of your installation it
will work differently on different bands. Change the configuration and
the efficiency for each band varies. Changes can be as small as swinging
your boom over to the opposite tack. Live with it and get on with using
your SSB. Don't fall victim to "paralysis by analysis".

Greg
S/Y TUULI
VE0ACR/CFA2577

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