SWL Balun
 

Hi.
Has any body any simple balun designs for a SWL long wire ?
I made a 9:1 transformer at the weekend, signals were improved, noise was
down.
I was wondering if there was any thing better ?
I am not even sure what a 9:1 is and whether its the right one for the job
?
The greatest improvements were on 20mtrs.
How can i improve say 80mtrs ?
I use a 20mtr long wire, coax feed , earthed with a earth rod 10mtrs from
the house.
All advice welcome
Regards
Jeff

Jeff,
For 80 meters, try a wire about 120 - 130 feet long. Feed
it in the center and you won't need a balun.
'Doc

Would that be so each half is 60- 65 feet long ?
And is 75 ohm tv coax ok to feed it ?
Cheers
Jeff

"'Doc" wrote in message ...
Jeff,
For 80 meters, try a wire about 120 - 130 feet long. Feed
it in the center and you won't need a balun.
'Doc

Jeff,
Yes, 60 - 65 feet per side. As long as you aren't
transmitting,
75 ohm TV coax, or 50 ohm coax of almost any kind will work just
fine. Get it up as high as possible. If you have to 'bend' it
a
bit to make it fit your space, it shouldn't really affect things
very much. It may not be 'better' than what you're using now,
but
it will be different, so you should hear things you may not be
able
to hear now. Good luck...
'Doc

On Thu, 29 Jan 2004 20:40:31 +0000 (UTC), "JEFF UK"
wrote:

Hi.
Has any body any simple balun designs for a SWL long wire ?
I made a 9:1 transformer at the weekend, signals were improved, noise was
down.
I was wondering if there was any thing better ?
I am not even sure what a 9:1 is and whether its the right one for the job
?
The greatest improvements were on 20mtrs.
How can i improve say 80mtrs ?
I use a 20mtr long wire, coax feed , earthed with a earth rod 10mtrs from
the house.
All advice welcome

Jeff, the biggest reason for using a BalUn for SWL is if you are
trying to isolate the antenna system from the local RF fields in your
house. These fields can result from noisy light dimmers, to poorly
shielded computers, to a noisy set of brushes on the blower for a
furnace...

If you get lots of interference of this sort, then a BalUn might be
appropriate. Otherwise, it's not worth the trouble.

Generally, this sort of interference is worst with those who have
their short wave radios upstairs, throw a wire out of a window for an
antenna, and use the electrical system ground as the counterpoise to
their antenna.

However, if you install a dipole high in the air, away from your
house, chances are you won't hear enough of a difference to make a
BalUn worth using.

73,


Jake Brodsky, AB3A
"Beware of the massive impossible!"