SSB

[Don S/V ILLusion]

1) What is a twin lead?

2) Is the length you refer to the length of one leg of the V or the entire length of the wire of the V?

3) If the deck to mast is 55' and the two ends are 12'6" apart, would that help you point me in the right direction to find out what percentage of SSB channels I could use? If it's like 70% or more, then I think this is the solution for me because it sounds a lot cheaper then a 23' whip antenna and easier.

twin lead is also called "ladder line" as it looks like a ladder - two separate conductors with spacers which look like ladder steps equally spaced so as to keep the two conductors at equal distance. You might remember it as "TV twin lead" which was common in the days when folks had exterior tv antennas.

Length of the entire antenna - unequal lengths of each half make it another design altogether and would overly complicate this discussion.

Frequency/length - with an approx total length based on your mast height, you might be able to run a total of 130 ft of wire which, if fed properly as I described, would make an effective antenna on all marine frequencies from 2.182 - 25 MHz plus most of the ham bands if you ever got interested. You might have a problem loading the antenna on 2182 as most of the so-called marine auto-tuners are crap when it comes to proper matching devices but if you are on 2182, you probably have better stuff to worry about...

 

[Phantomsailor]

Regarding Phantomsailior's comments, he is correct but I believe the discussion is not so much what can work but rather degrees of effectiveness.

Don, Gordon West conducted on the air tests with stations different distances away. In every instance, the direct connection to the water via a thru-hull, or copper ribbon put directly into the water gave the best performance. The link to Gordon's test results was posted by windward54 and is here: www.kp44.org/ftp/seawatergroundingfor_HF_Radios_byGordonWest.pdf

I've used balanced antennas aboard also. Specifically 40 & 20 meter sloped dipoles, no tuner required. They work well though I find that my insulated backstay/antenna tuner/seawater ground-counterpoise setup works just as well. I wonder about the practicality of an inverted vee such aboard. How do you run the twin lead to the feed point? How do you bring the twin lead below to the tuner? I can see hoisting the vee with a halyard while at anchor or at the dock but how does one use the vee underway?

In Franklin's case, an inverted vee with 55' legs would yield a lower frequency limit of roughly 4 Mhz. Marine SSB channel 4A is at 4.146 Mhz. The only "guarded" marine SSB distress channel is 2.182 Mhz. Inverted vee antennas are about 5% shorter in length than a corresponding dipole given a "vee" angle of 45 degrees. As the angle is reduced, the antenna has be longer for a given frequency. I assume given the geometry of most boats, that the vee would slope to some extent. I don't know what that would do to the lowest resonant frequency or whether it would cause directional effects evident in sloping dipoles. Interesting discussion.

 

[Franklin]

Ok....now I'm a little lost. Can an inverted V (left side of picture) work on most or all freq or does it need to be like a ladder on the right side of the picture?

 

[windward54]

Hey Randy, you stole my link! I used that one earlier! It is a good one though as lots of people still look for the magic 200 square feet of ground plane even though it is no longer needed with today's equipment.

Franklin, the reason for twin lead is that you feed one leg of the antenna with the positive side and one leg of the antenna with the ground side of the signal. Problem is, my tuner (ICOM AT140) has only one line out (GTO15) so you have to have a counterpoise in place. (It would look like figure A)

I've seen three ways of having an antenna on a boat with no backstay. 1. use a 23' mast, 2. install a fake backstay, 3. cut up and install on the shrouds using multiple isolators and interconnecting wire. The last one was the oddest thing you ever saw. The owner used to have a Hunter 410 and was in Newport Beach. He claimed it worked just as good as a backstay antenna. He has since sold his boat and moved on.

 

[Phantomsailor]

Hey Randy, you stole my link!

Windward, read it again, I gave you credit

 

[windward54]

Sorry! I'm at work and was finishing up my break. Got in a rush! I'll be on the air from Catalina this weekend if you want to give a holler!

KI6CZP
WDE4472

 

[Phantomsailor]

Ok....now I'm a little lost. Can an inverted V (left side of picture) work on most or all freq or does it need to be like a ladder on the right side of the picture?

Like the left side of the picture. The twin lead to the center is flat and about 3/8ths of an inch wide. Ladder line typically is about 3 - 4 inches wide but also flat.

 

[Phantomsailor]

Sorry! I'm at work and was finishing up my break. Got in a rush! I'll be on the air from Catalina this weekend if you want to give a holler!

KI6CZP
WDE4472

Wanna try 5330.5 at 1700 Pacific tomorrow, Saturday 1/31? Or maybe 6A (6.224.0 Mhz) same time? I'll be anchored out in SF Bay tomorrow night - should be fun.

 

[windward54]

I'll give it a try. 5330.5 is limited to 50 watts ERP, so that might be tough to get out that far. I haven't tried 60 meters much. I'll give it a try at 1700, and if it doesn't work, we can shift to 6A at 1710.

 

[Phantomsailor]

I'll give it a try. 5330.5 is limited to 50 watts ERP, so that might be tough to get out that far. I haven't tried 60 meters much. I'll give it a try at 1700, and if it doesn't work, we can shift to 6A at 1710.

Sounds good, talk to you tomorrow.

 

[mutualfun]

Hey Karl. I did not steal nothing. Ya had trouble with reading. It happens to us all. Have a good weekend.
Randy

 

[windward54]

Sounds good, talk to you tomorrow.

Missed you out there, but did get to talk to someone on 60 meters up in Yosemite and another over in Redding. Sixty meters was hopping!

We'll have to try again!