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!"