Thanks, Richard - I'll give it a try.

Richard Clark wrote:
On Wed, 19 Nov 2003 16:29:47 -0500, Jon Gauthier
wrote:


I have a Grundig YachtBoy SW/MW receiver that I'd like to connect to an
external long-wire antenna, but I'd like to have the antenna on the
roof, while I'd be listening in my office in the basement. I'd like to
make a couple of simple baluns to match it to 75 ohm coax. What's the
impedance that the receiver is expecting? It's just a phono plug
input... Grundig's web site is, ah, not very technical...


Hi Jon,

The matching doesn't really matter all that much for a receiver,
unless it is through an antenna tuner (quite useful even for casual
SWL). This cuts down on intermods and desense caused by local AM
stations (you would be surprised how much they can hammer your DX
without being heard).

On the other hand, the advantage of coax (50/75 Ohm) is in isolating
the noisy environment of the home from the signal path by allowing the
antenna to be remote. Using a feedpoint choke insures that noise does
not get into the picture. That choke can be in the form of 6-10 turns
of coax in a 4-8" diameter, or using a HAM 1:1 Current Balun
(generally 10-25 ferrite beads that fit over the jacket of the coax
cable at the feedpoint end OR the coax wound through a large ferrite
torus 3-5 times).

73's
Richard Clark, KB7QHC