In article , mike
writes:

Given I am currently using 75 ohm coax to feed my random wire, I
believe I could use a 300 ohm to 75 ohm (4:1) TV twin lead to coax
converter and get away with it.

Please correct me if I am wrong, but I think I would attach the random
wire to one terminal of the 300 ohm input. The other would go directly
to earth ground, or via a gas arc tube to ground.

On the other side, I would attach my coax cable.

To give the coax feeder a ground at the antenna end, I would to open
up the converter and solder in a ground wire on the coax sheild
terminal. This would kill off common mode currents.

This would give my antenna feeder system a matching transformer plus
give the antenna a direct path to ground.

Theoretically, I am I missing anything?

You could simple attach the 300-to-75 Ohm matching thing to the long
wire and use the coax...provided that the Z-changing-transformer can
handle HF. It won't be good if it's just a TV accessory; those seldom go
down to 30 MHz.

You might check the "300 Ohm" side of the transformer to see if it
actually has a DC path across it (an Ohmmeter will show that). Such an
accessory doesn't always have a DC path there. If it ain't there, no sense
in using it for your application.

The long-wire's impedance is going to range all over the place on HF so
it won't make much difference to a 75 Ohm coaxial cable feed. Most
frequencies will be way off in impedance matching regardless of the ultimate
impedance of the receiver.

Keeping the coax feedline offers some protection from household QRM
that is between receiver and antenna.

Len Anderson
retired (from regular hours) electronic engineer person