I'm using a off centre fed dipole. Its 66ft long and is a fed a third of the way in. The balun consists of a T200-2 wound bifilar with 17 turn of speaker wire (cheap speaker wire at that ).

The antenna will tune 80m-10m with the ATU in my TS-570. But my main goal is 40m.

I feel the balun could be better. I worked Japan with it last night on 40m but I feel it was more of a fluke then being down too my antenna construction skills.

The antenna goes from 12ft up too the balun which is 27ft up and then the short leg of the anntenna drops down to 6 foot.

The question is, How should I have constructed the balun?

Are you talking about the balun at the feedpoint, or one further back along the coax?

Steve G3TXQ

If it's working Japan 40m on 10W I wouldn't touch it.

The balun is at the feed point.

So, is it a 4:1 or a 6:1, and is it a voltage balun or a current balun ?

Steve G3TXQ

If your trying to catch me out it is working. How do you tell the difference between a voltage and a current balun? I just copied these instructions.

http://www.sdarc.net/wp-content/uploads ... Baluns.pdf

Not trying to catch you out - just trying to understand what you are currently using.

The link you gave shows a 1:1 voltage balun and a 4:1 voltage balun, which did you build?

Steve G3TXQ

I built the 4:1. Have you got any links too any websites to show the difference between the winding's for voltage and current?

http://www.qsl.net/ta1dx/amator/broadband_baluns.htm

Drawing B is what you built - a 4:1 Voltage balun.
Drawing D shows a 4:1 Current balun.

The voltage balun will tend to force current back down the coax braid, making it radiate as well as the dipole; the current balun will tend to stop it.

Steve G3TXQ

I suppose that might be the reason so many "New Carolina windoms" do not perform?

So looking at those diagrams a current balun should use 2 torroids?

Correct! You can't build a 4;1 Guanella current balun on a single core.

Steve G3TXQ

No, they're designed to use the coax braid as a radiating part of the antenna for a set length of coax usually supplied which is why they also come with a 1:1 balun.

Windom - off center fed dipole uses a step down current balun. Feeder coax doesn't radiate.

Carolina Windom - off center fed dipole uses a step down voltage balun. Feeder coax designed to radiate for a specific length choked from the rest of the coax by a 1:1 current balun.

Conor you picked me up wrong, I understand the purpose of the centre radiator I was referring to the use of an incorrect balun on the New Carolina Windom not the OCFD.

Not quite, the "Carolina windom", uses a 4:1 voltage balun at the feed point, to induce the coax feed to radiate as a vertical section, and a current balun (choke) is placed 22ft down the feeder to stop it.
So you in effect, have a 22ft vertical radiator, as well as the 1/2 wave horizontal radiators.
And they cost HOW MUCH ??