SSB antenna

[INCOMMUNICADO]

Hi All. I know this is a can of worms.I would like to know what SSB antenna solutions were found for your 365s. Thanks Allen

[BlameItOnBuffett]

I have a split backstay with insulators on one both sides, with another up high.

[POG]

Allen,

It strikes me as a bit incongruous that a boat named INCOMMUNICADO is about to be fitted with a SSB radio... Oh well.

I did install a SSB radio on POG – hull 118 – in March in anticipation of sailing the boat to New Zealand.  I am least of all an electronic nerd so I hired a sailing HAM guy for a modest fee to hold my hand, by email and telephone at first.  As I am presently in my native Sweden for a couple of months and the boat is in the San Francisco Bay I can't be specific about wire gages etc but I will try to give a general description of what is involved.

Beside the radio itself you need an automatic antenna tuner, an antenna and a counterpoint.

The auto tuner is a contraption the insides of which manipulate the fixed antenna length to suit the particular meter band you are working on the radio.  It must be mounted away from the radio itself to prevent interference.   It should be located as close to the antenna as possible.  My radio, logically, is at the starboard nav station .  I  mounted the auto tuner box on the side of the hull just under deck by the port split main backstay.

The upper single wire main backstay serves as the antenna.  There is an isolator at the lower end, just above the split, and another one closer to the top of the mast.  The wire between the isolators is the antenna and should be somewhere between 20 and 25 feet long.  I forget the exact recommended number.  You connect the auto tuner and the backstay antenna with a rubber coated wire cable which you wire tie to the port backstay leg.  This cable is actually the same kind that is used in cars for the connection to the spark plugs.  You hose clamp the copper stranded core to the antenna part of the backstay just above the lower insulator and waterproof the connection with, for example, self vulcanizing rubber tape.

The counterpoint is a necessary base or spring-board to shoot the signal into the stratospheres.  Without it you will not be heard.  On a steel boat you just connect the auto tuner to the hull with a 2" wide copper strip and the entire  hull acts as a counterpoint.  On a fiberglass Pearson 365 you have to provide the longest run of 2" copper strip you can achieve from the bow to the tuner.  I bought 40 feet of the stuff and ended up with little left over.  

I started at the back of the anchor well on the port side and ran the strip on the stringer by the top of the water tank and then down under the floor in the forepeak.  You must keep the strip away from the bilge water.  I used  Bondo to attach it under the floor through the main cabin and then up behind the stove and the port storage aft of the stove.  I cut a narrow slot in the bulkhead between the  port cockpit locker and the galley area for the strip to pass through.  For the last run over to the tuner you bend the strip to make it like the bellows of an accordion.  This makes it easy to turn and attach to the tuner.

Finally there is a special cable with pin connectors which connects the radio to the tuner and the antenna.

When I had completed the installation my ham guru came around and inspected it.   He was quite a sight, with a parrot on his shoulder and a captains hat with so much golden spaghetti on it that you could hardly tell the color underneath.  In a few minutes he was talking to another ham in Mexico, so I guess I did all right, though I have yet to learn how to use the darn thing myself.

I hope this is of help.  Good luck.

Carl  

[eveningebb]

An alternative to running a long copper strip for a counterpoint is the KISS SSB ground plane system.

Dirk

[PeteW]

I took a look at the KISS system which is simply a 9' 10" piece of insulated wire. I also downloaded the AT-140 manual to see what their engineers have to say about using 1/4 wavelength tuned radial stubs for a ground plane. A radial stub will look like a short circuit at the frequency that is 1/4 wavelength. The formula is 300/(Fmhz*4 )= 1/4 wavelength in meters.

Its pretty straight forward and here's the rub. To get a radial stub that works down to 1.6 Mhz it has to be 152' long. Consider that the longest radial stub you could fit in a 36' boat is around 36'. This means you can get a good VSWR down to 6.7 Mhz. If you can tolerate a 2:1 VSWR as ICOM specs for the tuner you could get a bit lower in frequency maybe 15% lower.

This also means that you will need multiple 1/4 wavelength stubs, each one shorter than the next to get a broadband ground plane. This is what ICOM recommends. So for operation up to 29 Mhz the shortest stub will be 8.25'. There may be some advantage in using a waterline connection for low fequency ground combined with tuned stubs for the higher frequencies.

Doing the math on the Kiss system limits your to operation in the range of 24.6 MHz

As for the length of the main radiating element, Icom says 23 feet min. Bare in mind that this length will create a 1/2 wavelength null around 21 MHZ making that frequency unusable. ICOM recommends a longer antenna to allow the AT-140 to be able to tune the full range of marine bands. They show that a 15 meter antenna will provide full coverage of the 1.6 to 25 MHz bands. The mast on the 365 is 14 meters tall. So there are possibilities for stringing up a longer antenna.

Pete W. hull #6

[INCOMMUNICADO]

Carl, Dirk And Jim I thank yall for the reply.I do understand that Incommunicado should only be using smoke signals when in a life and death situation the reason for the grill on board.When in the southern Bahama in the winter good weather reports are hard to come by.One less butt kicking is a good thing.So I guess I will be drug into the twenty first century.I have read a lot on SSB instillation and operation and have a SSB guru that I love aggravating with my foolish questions.From what I have read and what yall have told me I think I'm on the right track.Thanks Allen

[slokat]

Wind Tamer's SSB antenna also starts above the split backstay with an insulator there and another insulator just below the attachment on the mast.  Also have an auto tuner and alot of copper foil attached along the inside of the hull.

[RayNWanda]

I was looking at this for a possible solution, I really didn't want to cut a backstay.
http://www.gamelectronicsinc.com/ssb.htm

[BlameItOnBuffett]

We just had Sea-Tech, the guys who do Capn Navigation software for the Navy and Coast Guard, out for a speech to my squadron dinner (Galveston Bay Sail and Power Squadron). Afterwards, I pinned him down for more info on the antenna and the counterpoint. He said he absolutely goes with the new KISS and the GAM system that others have identified in this thread. He says that they always work. Period. He would not recommend anything else.

info@sea-tech.com

[Sta-Sea-Dawn]

I am totally befuddled ...but nearing the point where I have to find a SSB for Sat-Sea-Dawn.  I want something that I can get the net and weather information on.  I am not a ham or even SSB savvy.  I need to find a make and model that will receive the weather and net that will not break my meager budget....O'woe is me the poor sailor....I have a main back stay that has the isolators already installed....ideas...names of SSB that will suffice for listening.  I do not rally need to transmit unless I have water around my ankles...then just yelling probably not work....lol