On Wed, 01 Mar 2006 18:20:29 +0100, Charly wrote:


Dear all,

Usualy, people use 9:1 balun to connect a wire or dipole antenna to a 50 ohm coax.

A resonant dipole, I believe, is about 72 ohms. Connecting it through
75 ohm TV coax to a 50 ohm receiver input should be a near ideal
match.

On non-resonant frequencies, the dipole will present different
matches. That shouldn't be a problem, though, just for listening on a
sensitive receiver.

A balun won't give you a decent match except on the single frequency
it is designed for. That's one problem you run into, putting a balun
on a multi-band or multi-frequency antenna.


If I use a basic TV coax (75 ohms) I suspect I will need a 6:1 balun instead. If
so, how many turns of wire should I use for primary and secondary windings ?

I don't know the impendance of the antenna connection of my radios (ATS 909 +
ICF SW100), so I intend to give a try with the coax I have in hand.

If it's a coax-type connector, the input should be about 50 ohms. If
it's screw terminals or a plug-in terminal, I'm guessing it's for
higher-impedance antennas like a random end-fed wire.

bob
k5qwg



Thanks in advance for your help,

Charly