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-   -   HF/VHF/UHF transiver (https://www.sailnet.com/forums/gear-maintenance/50610-hf-vhf-uhf-transiver.html)

Arunas 01-18-2009 12:56 PM

HF/VHF/UHF transiver
 
Hello,
may be somebody have experence with SSB radio antenas on backstays. On market found only one type of such type of antena. This product very expencive. www.gamelectronicsinc.com

The Split Lead antenna eliminates the need for high-voltage backstay insulators, cutting bachstay and Insulators cost very high. Also needed infor regarding ground plates suplyiers.
Arunas

Gary1 01-19-2009 09:23 AM

The simple bottom line is that you have to stop the RF from a transmitter from touching the mast. That means insulators. If the RF does get to the mast, standing rigging, etc., it's not going to do anything but short out, because the rig (had better be) is tied to ground.

The contraption on gam electronics page must be some kind of folded dipole or something, because it certainly isn't very long. Certainly not a quarter wave length at 40 meters, which is about where you'll be transmitting most of the time.

Norseman insulators aren't THAT expensive.

The other real option is to put on a multi-band HF antenna like the one from Shakespeare. Shakespeare Marine Antennas Specifications: Galaxy 5390 SSB

It's big, tall, and heavy, but they work.

Personally, I'd be leery of that folded dipole thingy.

btrayfors 01-19-2009 10:42 AM

Arunas,

You don't need insulators and you don't need a ground plate.

On most boats, you can rig an "alternate backstay", hoisted with a spare (rope) halyard and tied off -- again with a short length of rope -- to the pushpit on one side of the boat. The best material to use is insulated stainless steel lifeline. Put a loop in each end, using Nicopress sleeves or s/s clamps.

Run a length of highly insulated wire like GTO-15 from the tuner, located belowdecks as close to the base of the "alternate backstay" as you can get it, to the bottom of the "alternate backstay". Make sure the connection is good and tight.

You will need an RF ground. The easiest is to run a wide copper strap from the tuner ground lug to the nearest bronze thru-hull.

Bingo! That's it. You've got a passably good setup for HF/SSB communications.

For VHF and UHF, you'd need a separate dedicated antenna.

Bill
WA6CCA

windward54 01-19-2009 11:52 PM

Arunas, I opted to use the Gam antenna. I hated the idea of cutting my backstay. Also, a number of my friends have used their backstays, and had a corrosion problem which affected the performance of the antenna. And if you figure in the cost of the insulators and the rigging cost, there really isn't much of a difference in price. Best part of installation of the Gam, as long as you don't have a split backstay, it is easy to install the antenna by yourself at the dock. You just slide it up the backstay and use zip ties ever 5 or 6 feet. Because the antenna is sealed in plastic, no need to shove it up 7 feet above the deck to protect from RF burns. According the Gordon West, it actualy works better with a low angle, so I anchored the bottom to the stem on my turnbuckle.

How does it work?? I've found the Gam is just as effective if not slightly better then an insulated backstay. I've had good signal reports into Japan and Central Mexico from my dock in Southern California, even with not the greatest band conditions that we have right now.

As for a groundplane, I took my general ticket class with Gordon West. He recommended using a thru-hull, using the same thru-hull for both the tuner and transceiver. Just make sure the thru-hull is always in the water. Try it first, as it is the easiest to do. If it doesn't work for you, you can always try the next hardest way and that is running copper foil every where. Last is the dynaplate.

http://www.kp44.org/ftp/SeawaterGrou...GordonWest.swf

SimonV 01-20-2009 09:32 AM

So let me understand, my crawling around the bowels of my boat replacing the copper grounding strip was a wast of time and money. I should have just earthed to the through hull fitting (bronze).???

N0NJY 01-20-2009 10:22 AM

Quote:

Originally Posted by SimonV (Post 434721)
So let me understand, my crawling around the bowels of my boat replacing the copper grounding strip was a wast of time and money. I should have just earthed to the through hull fitting (bronze).???

Yep, pretty much.

There's WAY too much "myth and folklore" out there, and too many people on this site and others have very little real knowledge of how RF and radio systems actually work.

So, they will tell you all sorts of things that really either aren't true, simply aren't helpful or simply won't work.

You need a counter-poise for a whip antenna. It can be something as simple as a car body or as complex as a metal hull on a ship. But running copper rods, grounding strips and so forth under the bowels of the boat isn't going to help. It'll get you dirty, and it really isn't that efficient :)

windward54 01-20-2009 11:16 AM

Sorry SimonV, but it looks that way. I ran a 4-inch copper foil from the transceiver to a thru-hull, and a second foil from the tuner to the same thru-hull, and I get good signal reports. Running the two strips of foil for the ground took me all of about 30 minutes. That's why I tell people to try this first before punching a hole in the hull for a dynaplate or running foil all over the bowels of the ship.

sailingdog 01-20-2009 12:24 PM

You're assuming they're using metal through-hulls, which isn't always the case anymore. :)
Quote:

Originally Posted by windward54 (Post 434776)
Sorry SimonV, but it looks that way. I ran a 4-inch copper foil from the transceiver to a thru-hull, and a second foil from the tuner to the same thru-hull, and I get good signal reports. Running the two strips of foil for the ground took me all of about 30 minutes. That's why I tell people to try this first before punching a hole in the hull for a dynaplate or running foil all over the bowels of the ship.




N0NJY 01-20-2009 01:56 PM

I've been looking at a way to turn shrouds into an inverted Vee. If I do it, I'll do a write up and show how it's done.

Won't be till well into the summer months, when I have time to work it out and look at what sort of rigging I need to change out.

(Of course, I have a fiberglass boat so it will be easier than some people's boats will be)

Just for general knowledge an inverted vee is a balanced antenna, there's no need for special grounding and weird plates, grounds and strange ideas. Cut the wires to length, insulate the ends, connect your feed line to your tuner and go from there. You don't really have to bother with working out lengths even, because your tuner will "take care" of that problem for you.

But - enough for now...


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