"Steve Lusardi" wrote in
:

Larry,
Excellent explanation, but I would like to know if I understood it
correctly. I believe you stated that ,yes, some radiation would be
lost with the slightly out of phase, grounded stay, coupled current
radiation, but you did not state how much of a performance impact this
would make. As I have an SEA 330, I have power to spare on the
transmitter side, but the split lead antenna's receive performance was
not mentioned, nor any effect this arrangement would make in its
omni-directional ability. I guess the question I need to answer, is
this an affordable alternative to the insulated stay? Could you
elaborate? Steve



Oh, it probably works just fine. Shunt fed antennas have worked great
for years. The problem I see in it is more related to how are we going
to keep seawater out of the insulating material between his feed and the
stay to keep the tuning stable and to keep the wet device from arcing on
some frequencies where it's at a high impedance point.

The only real way to tell how well it works is to just order it and
install it TEMPORARILY WITHOUT THE HOLES and try it out on your
backstay. If it works, install it. If not, send it back and get a
refund.

Are you SURE your backstay is grounded at the BOTTOM? That would be
very unusual in a production boat.

I'd say before you send him all this money, let's hook the RF output of
the SEA autotuner directly to the bottom of the backstay and any kind of
ground right there at the dock. Just run a jumper cable from the tuner
ground post to the engine block as directly as you can to test it. If
the bottom of the backstay is grounded it simply won't find a tuning,
especially on the lower bands. just sit the grounded tuner under the
backstay on the seating, anyplace it won't fall overboard is fine, but
as close to the backstay as you can temporarily located it. Keep the
wire from the tuner's high voltage output to the backstay as short as
possible. Listen to the receiver AFTER pushing the TUNE button and
letting the autotuner find a tuniing solution as tuning also affects
reception. If it will tune and seems to receive well, call someone at
some distance, not in your area, that you've prearranged to have
listening on the phone, maybe a couple of hundred km away. Connect the
cellphone to them so you can listen to your own signal at a
distance....above 6 Mhz in daytime, below 6 Mhz at night.

If it works, just install it! Problem solved!

If you can't find a way to get a ground to the temporary installation,
that's easy, too. Drop an anchor chain over the side and let it lay on
the bottom under the boat. Boy does THAT make a great ground! I use a
trailing wire about 30 meters long behind the boat under sail at sea.
It's just a plastic covered #16 piece of hookup wire the end of which
has been dipped in sealer so the water can't get up into it and rot the
wire. I did have a can lid on the end of it making a little sea anchor
to hold it out behind the boat, but SOMETHING BIG fell in love with that
and SWALLOWED it and half my ground wire! He must have needed iron in
his diet...(c;