In article , m II wrote:

Good idea. This may also motivate me to wind that matching transformer
I've had plans for. I found a nice fat toroidal core for it in a
junked microwave.

I will have to look through the past postings to see what the
consensus was for the ratio. Nine to one? four and a half to one?

I picked 3:1 (15:5 turns on J or 77 formula ferrite),
(9:1 impedance) at the antenna end of the coax.

One source I'd read had a (best match receiver input) impedance vs
frequency graph for a given length of wire. (ARRL Antenna Handbook?).
It bounces up and down all over the place, with a few thousand ohms at
half wave, down to the 50 ohm range for a quarter wave. So a nominal
450 ohm was a resonable average.

Another example: The R-1000 HF high impedance input has a rating of
1k ohm, which they get from a matching transfomer in the front end.


Mark Zenier
Googleproofaddress(account:mzenier provider:eskimo domain:com)