In article ,
Albert P. Belle Isle wrote:


Yes


Bruce in alaska
--
add a 2 before @

On Sun, 26 Dec 2004 20:36:21 GMT, Bruce in Alaska
wrote:

In article ,
Albert P. Belle Isle wrote:


Yes


Bruce in alaska

Bruce -

Thanks for responding.

I plan to place the output of a 1-30MHz Polyphaser isolator (fed from
my AT140 with less than 6" of hot lead) within 8" of the solid deck
area through which my lower shroud is fed. From there I can run the
GTO15 directly up to the mid-point of the leading edge of each
spreader, and connect it near the top of the (aluminum) mast.

With the mast and Polyphaser grounds connected to the keel (and
isolated by the Polyphaser from my DC/60Hz grounds that single-point
to the prop shaft), I hope to end up with a 50ft folded monopole whose
wire radiator is parallel to and separated from the mast by about one
foot.

I'd like to make as small a penetration next to the shroud turnbuckle
as possible, and am looking for any tips you might have on waterproof
bulkhead-penetrating connector options for the in-cabin and above-deck
portions of the GTO15.

I've tried to describe the overall scheme in the hope that you might
also comment on it.

Thanks for your time.

Al
s/v Persephone
Newburyport, MA

In article ,
Albert P. Belle Isle wrote:

On Sun, 26 Dec 2004 20:36:21 GMT, Bruce in Alaska
wrote:

In article ,
Albert P. Belle Isle wrote:


Yes


Bruce in alaska

Bruce -

Thanks for responding.

I plan to place the output of a 1-30MHz Polyphaser isolator (fed from
my AT140 with less than 6" of hot lead) within 8" of the solid deck
area through which my lower shroud is fed. From there I can run the
GTO15 directly up to the mid-point of the leading edge of each
spreader, and connect it near the top of the (aluminum) mast.

With the mast and Polyphaser grounds connected to the keel (and
isolated by the Polyphaser from my DC/60Hz grounds that single-point
to the prop shaft), I hope to end up with a 50ft folded monopole whose
wire radiator is parallel to and separated from the mast by about one
foot.

I'd like to make as small a penetration next to the shroud turnbuckle
as possible, and am looking for any tips you might have on waterproof
bulkhead-penetrating connector options for the in-cabin and above-deck
portions of the GTO15.

I've tried to describe the overall scheme in the hope that you might
also comment on it.

Thanks for your time.

Al
s/v Persephone
Newburyport, MA



What is the deck made out of? (material) Is it conductive? (metal)
If so, then a Thru-House insulator will be required, and should be at
least 2" in diameter. If not, then anything would do, but a Thru-House
insulator is still the thing to use for that job. Remeber that the
GTO-15 IS part of the antenna, so don't strap it to any other structure.
I suspect that your PolyPhaser isn't going to provide the RF Ground that
you think it will, as compared to REAL RF Ground, but that is just an
opinion.


Bruce in alaska
--
add a 2 before @

On Mon, 27 Dec 2004 19:49:17 GMT, Bruce in Alaska
wrote:

In article ,
Albert P. Belle Isle wrote:

On Sun, 26 Dec 2004 20:36:21 GMT, Bruce in Alaska
wrote:

In article ,
Albert P. Belle Isle wrote:


Yes


Bruce in alaska

Bruce -

Thanks for responding.

I plan to place the output of a 1-30MHz Polyphaser isolator (fed from
my AT140 with less than 6" of hot lead) within 8" of the solid deck
area through which my lower shroud is fed. From there I can run the
GTO15 directly up to the mid-point of the leading edge of each
spreader, and connect it near the top of the (aluminum) mast.

With the mast and Polyphaser grounds connected to the keel (and
isolated by the Polyphaser from my DC/60Hz grounds that single-point
to the prop shaft), I hope to end up with a 50ft folded monopole whose
wire radiator is parallel to and separated from the mast by about one
foot.

I'd like to make as small a penetration next to the shroud turnbuckle
as possible, and am looking for any tips you might have on waterproof
bulkhead-penetrating connector options for the in-cabin and above-deck
portions of the GTO15.

I've tried to describe the overall scheme in the hope that you might
also comment on it.

Thanks for your time.

Al
s/v Persephone
Newburyport, MA



What is the deck made out of? (material) Is it conductive? (metal)
If so, then a Thru-House insulator will be required, and should be at
least 2" in diameter. If not, then anything would do, but a Thru-House
insulator is still the thing to use for that job. Remeber that the
GTO-15 IS part of the antenna, so don't strap it to any other structure.
I suspect that your PolyPhaser isn't going to provide the RF Ground that
you think it will, as compared to REAL RF Ground, but that is just an
opinion.


Bruce in alaska

Bruce,

The deck is FRP, Baltek cored except in places where things are
mounted - like the lower shroud in this case - where it's solid FRP to
avoid sideways penetration of the core by any water that might leak
around a fitting's penetration.

Since it is well-insulated, I was looking for the smallest penetration
and for some kind of connector that would provide a waterproof
connect/disconnect for both the GTO15 radiator above deck and the
GTO15 hot-lead below deck.

The RF (and lightning) ground will be an antimoneous lead keel with
the Polyphaser capacitively coupling it to the common DC/60Hz gound
system just as it couples the hot lead to the antenna. The lightning
arrestor portion of the Ployphaser spark-gaps to the keel/RF ground.

Separating the keel/RF/lightning ground from the single-point DC/60Hz
ground avoids a DC/Galvanic path from the water around the propeller
shaft through the DC ground system to the water around the keel.

The keel measures around 6ft long and 3ft deep, and has a large bulb
on it. I estimate its surface exposed to seawater at well over 30sqft.
The ground foil run to it from the Polyphaser output ground is 8ft

The effective drive point and its ground are both at the output of the
Polyphaser, which provides a 1-to-30MHz low-impedance coupling of both
to the output and ground of the AT140 (less than a foot away).

I can keep the hotlead length under 6 inches from the Polyphaser to
the base of the solid fibreglass area through which I want to pass a
connector to the GTO15 radiator that goes from the deckside of that
connector up the mast.

The boat is a 36 foot auxiliary sloop, so the keel is a _lot_ more
metal in the water than the usual bonded group of through-hulls. It
will be connected to the Polyphaser output ground point with 3"x10mil
grounding foil down the interior hull side to the keel bolts.

Since the amount of metal is a lot more than the radials I've used on
my roof-top multiband vertical antenna at home, I thought it'd
suffice.

Am I missing some particular consideration that causes your concern
about the effectiveness of the RF ground? Is the 8ft run of foil to
the 35sqft of keel surface too small for an effective counterpoise to
the 50ft folded monopole? I can computer-model and analyze till I'm
blue in the face, but I have little direct experience of what sea
water does in such a case, and would gladly accept inputs on same.

Thanks.

Al
s/v Persephone
Newburyport, MA

Here's some ASCII art to try to depict the set-up

___
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
50' | | GTO15
Mast | | Wire Radiator
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |____/---||------- AT140 tuner output pin
| ____Polyphaser
| | \---||------- AT140 ground/DC ground system
\ \ (single-pointed to prop shaft)
strap\ \ strap
\ \_________________
\__\ \
\ KEEL \
\ \
\________________\