Fritzel FD4 : Very high SWR, please help!

[ON3RMB]

This weekend I've installed my FD4 wire-antenne (newly bought) but when I've tested it, I noticed a very high swr on 80M, 40M and 20M. Only 12M and 10M is working good (SWR=1)

On 80M the SWR is "eternal".
On 40M the SWR is 3
On 20M the SWR is 2.8

I've measured on the FM modulation. Power of 10W (Icom 703)

Does it have something to do with the installation of the balun (taped it against the mast)?

Here are some pictures of the installation:


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Thanks in advance for your help!

[W0UZR]

Your wire isn't in a straight line. the SWR will be greatly affected if you don't have that in a straight line. And are you at the height that it's suppose to be?

On 2nd look, it looks like you have your transformer where your balun is suppose to be. And that is suppose to be ABOVE a choke balun. The transformer is suppose to be down one side of the antenna about 1/3 from the end. And I'm not sure what that is above your antenna. I didn't read that anything is suppose to be up there.

[ON3RMB]

Your wire isn't in a straight line

True. I didn't know it would cause a SWR that high! Will solve that asap.

And about the correct height...

1 isolator = 7m (+/-23ft) above the ground
Balun = 13m (+/-43ft) above the ground
2 isolator = 7m (+/-23ft) above the ground

I've read that there are many different ways to install the antenne.
Some install it like an inverted V and others install it in a 100% horizontal way.

A few weeks ago I had the antenne installed in the attic and it was even better than right now.

[W0UZR]

What is that above your feed point? The pictures I saw reading on it has nothing up there.

And a 6:1 balun at your feed point, and your choke balun is below that. And a transformer goes down one side of your antenna stopping 1/3 the way from the end.

And is 80 your lowest band you are using that for? It's suppose to be a 1/2 wave length for 80 meters TOTAL length...

[ON3RMB]

What is that above your feed point? The pictures I saw reading on it has nothing up there.

It's for my Diamond CP62 (50MHz) antenne that has yet to be installed.

Yes, 80M is the lowest band I'm using the FD4 for. Total length is 42m. It's a 6:1 balun indeed.

And a 6:1 balun at your feed point, and your choke balun is below that. And a transformer goes down one side of your antenna stopping 1/3 the way from the end.

I don't understand what you mean here. My English is not that good I'm afraid.

[W0UZR]

On what I read a choke balun is Below the 6:1 balun. A choke balun is a coil of coax with about 6 to 8 turns on a 5 inch plastic tube. Coil up your coax that is connected to your 6:1 balun anotherwords.

And it looks like your transformer is fed 1/3 off center fed on the antenna. Take the total length of the antenna, divide it by 3, and that's where the feed point is.

On reading further, I'm wondering if a transformer is not available, then you can feed it with the 6:1 balun and the choke balun. ? Otherwise you just use the transformer? It appears that way because in one of the diagrams, I don't see the transformer. Well, read on it and see what you think.

Here is what I'm looking at what I'm reading and you can read on it. Here is the link.



http://www.xs4all.nl/~pa0fri/Ant/FD4/fd4eng.htm

Oh, and get rid of that thing for your Diamond antenna up there and don't put that antenna on that same support pole. It will interfere with the antenna.

[ON3RMB]

Thanks for your input W0UZR.

I'm now thinking of installing the antenne 100% horizontal, about 8meters above the ground.
The space between the balun and the CP62 will than be about 6meters. Hopefully that will prevent interference.
I don't want too many masts in the garden at this time.


Ain't it possible to let the balun "float" in the air? I was thinking about using some weight and a pully ...

[ON3RMB]

The picture below says that the end isolator of the longest leg should be about 3m above the ground. In that case I should lower it about 4m... Will try that out first.

[W0UZR]

To just support the ends of the antenna and the feed point hanging, then you will have the weight of the balun and coax choke and the coax going up to it, then that will make it sag a quite a bit. There would be way too much tention on the antenna wire to keep it straight, and it will break easy. And with the weights and pully, I don't think that you will be able to create enough tention to be able to keep it from sagging. But you can try different things and see what happens. Maybe it will stay pretty straight.

[ON3RMB]

Sorry, forgot the picture ...