"markvictor" wrote in
oups.com:

And the fact that your aluminum mast is gonded ...why challenge the
working parameters of your tuner? It also prevents those tingles you
refer to when someone(yes, perhaps foolishly) comes in contact with
that backstay or mast while TXing... And I'm sure you realize that
despite what anyones opinion of it might be, that plastic AT-130 is the
most common tuner in the fleet these days...and works well enough with
an INSULATED backstay and efficient counterpoise....
regards
markvictor




You obviously don't work around RF. This isn't AC power. At some
frequency, when something resonates, your shroud and your handrail could
be several hundred volts DIFFERENCE, which is the only way to get zapped.
There is NO GROUND in an RF system. 1/4 wavelength back from some
reference point, say the engine block at sea potential, there exists a
virtual open circuit at that RF frequency....a point of no current and
high voltage to that engine block. Divide 246 by the frequency in
megahertz to find how many feet that is. Every 1/4 wavelength, the
opposite condition repeats itself over and over. If your backstay is
64' long with an insulator at the top that always makes that point the
high impedance point (an open), where voltage is high and current is
zero, on 7 Mhz, the feedpoint at the tuner is very low impedance, indeed.
Current in the wire is high, voltage is very low at the tuner output.
The backstay is 1/4 wavelength long. On 14 Mhz, the backstay is two 1/4
waves long. The high voltage, low current at the insulator repeats
itself and the voltage on the tuner output is very high...high impedance.
The low impedance point on 14 Mhz is in the middle of the backstay,
again, 1/4 wavelength back from the insulator at the top.

If things are bonded with very short bonds together, there won't be a
potential difference between points, say the shroud and handrail of a
sailboat. But, if the shroud has a bond from the chainplate down into
the bilge back to the engine block "ground" and the handrail is bonded
back by the engine room, a significant part of a wavelength DIFFERENCE
exists between the two lengths of grounding bond. ANY conductor is an
ANTENNA, even the bonding straps, handrail, shroud. If the chainplate,
at some frequency, was 1/4 wavelength to the engine and the handrail and
its bonding system were 1/2 wavelength (or some DIFFERENT LENGTH), at the
point where the shroud comes over the handrail, there could be a
CONSIDERABLE difference in RF voltage right between them as you're
leaning over the rail touching the shroud.

However, at 150 watts on the yachtsman's little Icom, you won't feel
much. Raise that up to 1500 watts on my ham radio station and it will
light your fire, induced from that totally isolated backstay antenna...by
RF induction crossing these other conductors aboard. Raise it to 5-50KW
a broadcaster runs on AM and those kinds of potentials are MOST
impressive, indeed...(c;

Larry, I think this topic has become blurred, I am in agreement with
you ....and the fact that the backstay insulator (lower) is kept above
head level is for the purpose of avoiding the situation you mentioned,
ie. grabbing the handrail and backstay...I'm sure you're familiar with
them but I think that some people might find reading about Nicholas
Tesla's experiments using earth as a radiator interesting...

Read it again Gary...
Pay particular attention to the part that says "There is no ground in
an RF system"
you still have not answered:
1) Is a backstay horizontal or vertical?
2) If you are using your backstay as the radiating element in your
antenna system why do you insulate it?

"markvictor" wrote in
oups.com:

Nicholas
Tesla

Nikola. I've been fascinated with him since I was 8. I built my first
Tesla coil at 12. I built my biggest Tesla coil at 22. It was 11' tall
and produced sparks over 12' long....(c;

While touring the Smithsonian's Edison Exhibit (their "boy"), one of the
curators made the mistake of asking me what I thought of his exhibit. I
told him I found it very ironic, since the Smithsonian refuses to even
accept a bust of Tesla from a bunch of elementary students. "What's
ironic?", he asked. "This display is lighted with Tesla's flourescent
lamps, from Tesla's multiphase AC power system, using Tesla's ballasts,
transformers, alternators, high tension transmission lines and his entire
electrical system, right down to the watthour meter he invented to meter
it to you. The air conditioning and even that water cooler over there is
powered by Tesla's multiphase AC motors. Shouldn't this building be
running on DC from an Edison GENERATOR?"

He was not amused....(c;

PRICELESS...(c;

On 18 Dec 2005 23:33:09 -0800, "markvictor"
wrote:

Read it again Gary...
Pay particular attention to the part that says "There is no ground in
an RF system"
you still have not answered:
1) Is a backstay horizontal or vertical?
2) If you are using your backstay as the radiating element in your
antenna system why do you insulate it?

"Read what again"? I don't know what you are referring to that has any
connection to what you are talking about. "No ground in an RF
system"?? What point are you trying to make?

Your question "is the back stay horizontal or vertical". Well you
could consider it either I suppose depending on the size of the boat.
I am not sure what your question is about but I suppose most would
consider it vertical.

"Insulating the back stay when using it as the radiating element in
your antenna system". Yes most are done that way but they don't have
to be. Didn't you read Larry's post about that?

Ever heard of a gamma match or a shunt feed system? That allows a
grounded element to be fed RF.

Regards
Gary

Most people would be quite surprised to learn that Tesla built the
first power plant at Niagra Falls....I think Tesla was the Einstein (or
beyond) of the practical world...Question: What kind of power supply do
you use for a Tesla coil? Just curious...I remember at a school I went
to while in the Navy we had some type of a Tesla alternator that
transmitted static(?) electricity...hold a flourescent tube within
about 6 inches,it would light... I though, no big deal... then the
insructor used an incandescent lamp, and it glowed (albeit somewhat
dimmer than normal...) I was hooked..
Regards,
markvictor

Gary,
in case you have forgotten we are talking about boats here not a Ham
shack...
regards,
markvictor

In article .com,
"markvictor" wrote:

And the fact that your aluminum mast is gonded ...why challenge the
working parameters of your tuner? It also prevents those tingles you
refer to when someone(yes, perhaps foolishly) comes in contact with
that backstay or mast while TXing... And I'm sure you realize that
despite what anyones opinion of it might be, that plastic AT-130 is the
most common tuner in the fleet these days...and works well enough with
an INSULATED backstay and efficient counterpoise....
regards
markvictor


Looks to "Me" that this fellows MF/HF Marine Radio experience has all
been since the invention of the Marine Radio Autotuner. If he had some
experience with the old Northern N555 tuners, or any of the RF Harris
channelized Tuners, his outlook would certainly be broader. If he had
to actually learn to TUNE an open wire antenna thru a channelized tuner
as the frequency approched 1/2 Wavelength, his outlook would be
different. But hey, I for one, admit that MF/HF Communications in
Marine Radio, is on its deathbed, and has very little future in the real
world. One can't expect newbies, to learn this Art, just because it
used to be the way the world communicated back in the 20th Century.

Me

And now we arrive in the 21st century....that is what we are talking
about, me, reality as applied to TODAY, not what was in days gone
by...And yes,truth be told,I have installed satphones with global
coverage with a price competitive with most SSB installations, however
the airtime is still cost-prohibitive...and data rates can be
astronomical...but that too will change...building Adobe huts and
living in them is becoming a lost "art" as well...
The bottom line is.You either keep up with the technology, or get left
behind..
regards,
markvictor

"markvictor" wrote in
oups.com:

What kind of power supply do
you use for a Tesla coil?

My big tesla coil primary power supply was a 30KV 1A Xray transformer
with 230VAC heavy primary. The tank circuit was a home made capacitor
with copper plates separated by 1" thick plexiglass dielectric that
exploded many times so we went to 2" thick glass panes to stop it. The
primary coil was 32 turns of #12 wire suspended on glass posts around the
secondary with over (estimated as we lost count on the lathe) 50,000
turns of very fine enamel covered copper wire around a 4" diameter solid
glass rod, which glowed an eerie, but beautiful blue from the stress,
especially if it wasn't arcing to anything with a solid arc. The top of
the glass rod had a flange glued to it and the top had a copper threaded
rod up about 6" with a 1" brass ball screwed to the top of it. The base
of the glass rod was fit into a PVC drain pipe for support with a heavy
boiler plate base, the ground for the system.

RF was generated with carbon arc lamp rods in home made holders in the
tank circuit, which with 30KV of AC power had no problem arcing over...
(c; Our problem was power input. We only had 50A 230VAC service
available and if you got the rods too close together it would take out
the 50A breaker. The key was to get it pulling around 35-40A, unloaded,
then hold your breath as it flashed over and converted the RF load to
lightning...(c;

Everyone always wore meat cutters' stainless mesh gloves used to cut meat
with a saw to protect your hands from burns because the arc was quite
hot. Even then, you took a pretty good jolt when you became the path.
RF would also burn holes in your feet right through your sneakers, so we
lined the sneakers with tin foil to "distribute the load"...more fun.
You could stand to be the conductor for "most of the arc" for around 5
seconds before the RF heating became uncomfortable in your hand and feet.
Watching so-called safety rubber matting lighting up UNDER YOUR SHOES was
very exciting. Any kind of flourescent lamp within 100' of it would
light brightly, indeed, in your hand. The radiation field was very
intense....tearing up RF communications, I suppose, for miles in all
directions, but not too far as it had no large antenna to speak of.

Set it out in the driveway and let it arc to a lamp post or tree 10' away
will stop traffic on the street...

All in good fun. The "new" wears off after a while and I sold it to
another "coiler" for $300. The Xray transformer was worth that.