Uncle Peter wrote:
"Jeffrey D Angus" wrote in message
...

Unrevealed Source wrote:
I often see radios that someone has added the connector. I'd like to add
one to an old DX-150A, just for convenience since my longwire comes into
the house via coax. A already use a MLB between the longwire outside and
the coax; the antenna works great on radios with a 50ohm input.

Any advice? Thanks.
Ferrite is cheap. Why not put a 3:1 (turns) balun inside the
radio between the SO-239 connector and the original antenna
terminal.

(another) Jeff



There's no guarantee that the radio has a defined input impedance to begin
with!
You could try a balun to see what improvement it makes on various stations,
but with a random length wire the antenna impedance is going to be all over
the place. If you're really worried about matching, use an antenna tuner. It
probably isn't going to make that much difference.

Pete


I would add a small series capacitor (maybe 0.01 uF), not for impedance
matching but for safety in case a high-voltage fault develops inside the
radio. As Pete says, the input impedance over a 3:1 bandwidth will be
all over the map. You might match it over a 10% bandwidth. But 3:1? No way.

Bill Jeffrey