Hi Larry,
Thanks again for the advice to the ignorant.
What was all black box to me is now starting to turn a little brown or
a whiter shade of pale.
Should be setting off tomorrow. The boatyards here in Chaguramas,
Trinidad are filling up fast with new arrivals who will leave their
boats on the hard during the hurricane season. Friend Jack from
California left yesterday for quieter parts, but not before he made me
up a 40 foot primary hose for my scuba so that I could leave the
bottle on deck should I need to go over the side in a seaway - a great
but simple idea. He cut the hose in half and joined the two ends with
industrial air hose. On end goes to the mouthpiece and the other to
the regulator. Some may think it not good practice but he uses one and
is a retired submersion diver who has worked most of his life in the
oil industry. No more trying to snorkel under the hull to cut ropes,
nets and plastic bags from the prop or using scuba and having the tank
bang on the hull as the waves bounce it about.
If you ever come to Trinidad, be sure to meet Claus at "First Mate"
who is a first rate engineer of the old German school. He has a wealth
of experience and can repair anything as well as being able to
converse on a wide range of subjects including the recent discovery of
the Emperor Augustus's lost three legions in Germany. As a young
engineer on merchant ships he served under the former commander of the
U-boat of "Das Boat". Apparently the story is true. I have seen two
versions of the film; the original German one and the latest version
which had, at the final stages, the main participants being killed by
an air raid. This did not happen and was supposedly added for the
American market. Take a look at
http://uboat.net/flotillas/bases/index.html
There is a whole U-boat war saga that was focused upon Trinidad that
is very interesting and is featured in the excellent maritime museum
near here.
Anyway thanks so very much for your help and much appreciated advice.
Remember, if you come to either New Zealand, Australia or Malaysia -
let me know. I would be greatful to repay you by playing host.
Don't change
regards
Peter Hendra
RF will follow the outside of the coax shield, induced by the RF
radiating from the nearby antenna, back towards the radio. But, if it
causes no problem, let's not make one. On the air, RF interference into
a microphone circuit sounds like a rasping sound every time you start
talking. If it gets too bad, it'll go into wild oscillation making a
screaming noise in the transmitter's audio input, but, obviously these
aren't happening so I don't think you have a problem. If it gets into
any kind of modem, it simply won't connect to anyone. Yours works, so is
probably fine.
Ferrites don't need to be tight to the wire, just surrounding them. On
power leads, I use those square ferrites you can take several turns of
power lead wire around, filling it with wire. This also helps reduce
noise RF following the DC and control cable "antennas" back into the
radio receiver, as well as transmitter. Do these as close to the radio
as practical. As to the coax, RG-58 or 6, make an air inductor out of
it. Instead of cutting the coax as short as possible, leave extra on the
radio end and make a smooth, 8-10 turn loop in it about 15cm in diameter,
taping the loop so it will stay tight. The RF inside the coax is
unaffected. The RF sneaking back down the outside sees this series
inductance and is "somewhat" blocked. It reduces the backfed RF to
acceptable levels, even RF that's tearing up mic audio amps.
Another great way to both eliminate RF feedback down the coax and greatly
reduce the radio being destroyed by a static discharge from a nearby
lightning hit, is to route the coax to the engine block. Most backstay
antenna tuners are right over the rudder, inside a locker that's exposed
to the engine compartment. I like to route the coax to a coaxial surge
suppressor mounted in a little stainless (if possible) plate I can bolt
to any engine bolt I can get to. The surge suppressor will trigger on
any static high voltage pulse inside the coax, saving the transmitter,
but not the tuner, of course. This also bleeds any RF following the
cable back to the nav station instruments off to the engine block
(ground) so the coax from that point to the radio is nearly RF free. I
do the same thing to antenna cables on ham radios at home. I route the
coax down the tower, through surge suppressors mounted into a large
aluminum block firmly U-bolted to an 8' electrical ground rod in the soil
next to the tower, one of 3 that also ground the tower. This keeps RF
and lightning from looking in my hamshack for a ground path. I use a 20
turn coax "inductor", just like I described above, to make extra
protective inductance in series to reduce the risk even further. It's
worked for me since the 1960s with good success...(c; One hit blew the
top off the tower and just vaporized the coax back to my ground plate.
The coax and radios on the house side of that plate were untouched! Too
bad the beam antenna and top 3 feet of the tower were also vaporized,
just disappeared. All I remember is a blinding pink flash you'd expect
from a nuclear detonation and being deaf for days after the event....
I would much appreciate your help - once again.
Being back in the water again out of a hot and dirty yard is just
bliss. Using and having to pump your own toilet (- dismantling it due
to a blockage first), going to and fro by dinghy, rocking of the boat
and using the kerosene stove instead of an electric hot plate is like
being in heaven.
You can always tell a true sailor from the rest by just looking at their
faces at the dingy dock, especially if its windy enough to get them wet
on their way in from the anchorage...(c;
Just have to tune the rigging and I am off. All the little things that
need to be completed after a refit can be done under way.
Congratulations! Glad you're at sea, again.
Just remember:
It's always better to be standing on the dock, wishing you were at
sea....
Than to be at sea, wishing you were on the dock....
Larry