Red wrote in news:%sXQi.1096$932.869
@newsfe12.lga:

Richard...I'm telling you one of the worlds top antenna
designers
lives here and I just happened to be lucky enough to get his
help
setting up my radios. If he tells me tarnished silver is the
best for
HF I take his word for it..If our goverment flys him all over
the
earth to design develope and set up the best....that's good
enough
reference for me.

Joe

I bet Larry could tell a few interesting stories on this
subject.
Antenna designers are really in a world of their own. Back in
the day I
remember a group of antenna engineers that were hired to keep a
large
surveillence receiver antenna working. They would come down and
crawl
inside the antenna case with a small metal tackle box. After a
short
while you would hear some light banging here and there and then
they
would come out and test it. The tackle box they carried had
several
hammers in it they used to shape/tune the antenna with. In
conversation
with them and from reading on the subject I learned that when
it comes
to antenna design some of what you think should make sense,
actually
doesn't. And sometimes stuff just works when intuitively you
would think
it wouldn't.
Red



We COULD turn your 55' mainmast into a conical monopole, like the
gummit uses on HF, but the cage might interfere with the genoa...
(c;

About the banging, one of my technical college associates was the
wife of Dr Rufus Fellars, Chair of the Electrical Engineering
school at the Univ of SC in Columbia. One of the UHF TV stations
in Columbia had a bad reflected power from their multimillion
dollar antenna system 1200' up. They hired Rufus to correct it.
He took the measurements, did some calculations and drew up plans
to put 3 dents in the UHF feedline, creating another reflection
to cancel the one they had. Machinists installed the dents, and
when the station was turned back on, it had no reflected power
one could measure, making their big multikilowatt UHF beast very
happy, indeed.

Denting works at microwaves much better than HF, however. Dents
at HF frequencies are measured in hundreds of feet, not inches.

HF on a boat has but two antennas...a flagpole....a clothesline.
Neither antenna is "resonant" at the frequencies you want to use
them. So, we must always compromise by having a very lossy L-C
tuner in the line to match the complex impedance of the
clothesline, with its highly reactive component creating that big
reflection, to the 52 ohm resistive-only transmitter. This is,
virtually, a variable dent you can slide up and down the line
that also varies in depth and width to match the wide variety of
frequencies Marine HF has spread across. You are using the same
antenna system the Morse operator on Titanic used with his spark
gap CW transmitter, feeding a tuner to untuned wires between her
masts. If you look at qrz dot com and put in my call W4CSC into
the search engine, you'll see a picture of me holding a 300,000
volt ceramic insulator that failed around 70 KW on a pirate radio
ship I had befriended the captain and chief engineer of. The
tuner was built into the top of the military HF transmitter:
http://hawkins.pair.com/voanc1.shtml
It came from Voice of America in Greenville, NC, bought surplus:
http://hawkins.pair.com/voanc/voanc07.jpg
This transmitter was built into the fish hold of an old Canadian
offshore fishing trawler and installed at one of our little
shipyards for Rev R G Stair, who talks directly to his God and
rapes the women living on his commune in Canadys, SC. The boat
was supposed to be taken to Belize where he'd bribed the right
people to let him anchor offshore in international waters
microwaving his religious nonsense out to the boat for HF
transmission on the shortwave bands. But, the captain, a non-
religious man living in St Kitts to avoid American prosecution
about a pirate 100KW FM station they used to run from a sailboat
off NYC, was afraid the "brothers" were going to feed him to the
fish as soon as he got the boat in place and working. So, to
attract the FCC's wrath and prevent the boat from moving, he
transmitted on the pirate's favorite frequencies just above 7.3
Mhz in the 41 meter band at 70KW from the Wando River here. It
worked. FCC swooped down and confiscated everything making a big
show in the paper of what great bureaucrats they are at
protecting the airwaves of the rich and powerful, like Clear
Channel Commications, Inc. to keep the airwaves for themselves.

That insulator sure made an impressive arc when it exploded...(c;

Larry
--
You can tell there's extremely
intelligent life in the universe
because they have never called Earth.