SSB Antenna's & Interference


svcrusader <g4ljf@...>
 

Hi All,

I was interested to read Gary's comments on the Bantem SSB vertical.
I have had two brackets crack during 25,000 miles of sailing in the
past two years. Like all plastic fittings, they do not last that long
in the tropical sun.I keep a permanent back up in place now with two
very strong nylon cable ties around the antenna in case the bracket
gives way completely. I have seen this happen to another boat. It
can be expensive!

I also have had the top part of the antenna unscrew. Luckily I
noticed it before it fell off during one of my rare visits to a
marina, when at low tide, the problem was noticeable from the dock
wall. I would strongly recommend that all owners use Locktite or a
similar thread lock substance to stop the top half unscrewing.

As a keen radio ham I am interested in long distance communications
from the boat. I can vouch that the vertical does radiate a low angle
signal very well indeed. However, verticals are notoriously noisy on
receive, and the noise level on the SM2000 is very high, particularly
on frequencies above 10 Mhz.

I have overcome this to some extent by fitting a 12V coaxial relay so
that I transmit on the vertical and receive on the triatic between
the two masts. This antenna being almost horizontal is very much
quieter on receive, and it makes emails email and weather fax much
easier when signals are poor. You will find the coax from the triatic
behind the left hand panel above the nav desk. You will probably have
to fit a PL 259 connector to the bottom end.

The relay I used is a Totsu CX-600. I got mine from Henry Radio in
LA. If your radio has a pin out that goes to ground when you
transmit, then it's easy to fit. There is a 12V supply point at the
back of the nav table, or from the cigar lighter socket.

Does anyone have a cure for the interference caused by the fridge and
freezer controller units on SSB? (Loud bleeping sounds). I have spent
a lot of time on this and still have not completely solved the
problem. The later controllers are a bit better than those fitted in
2000, and if you power them from a short cable from a battery the
problem disappears altogether. It would appear that it is the yacht's
wiring that is radiating the RF. I have tried various chokes, but no
luck so far. Any help would be welcome.

Best Wishes

Ian Shepherd

SM2000 #299 Crusader

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