[TowerTalk] Using 75 Ohm Hardline

[K4SB]

Gedas wrote:
> Hi everyone. I was wondering if someone could recommend an easy and elegant method that would allow me to use a bunch of 7/8" 75 ohm hardline I have.

Easy.. visit your friendly Ace hardware and buy a 7/8" brass
compression fitting. Get the type which will allow you to screw/put a
reducer which will bring it down to 1/2".
Be sure you have removed about 3 inches of the end of the hard-line
leaving only the center conductor. Very carefully, thread the 7/8"
fitting which has the reducer over the hard-line and then transition
to a PL-259. Now, you may wind up with a little extra line, but if you
then make the run of hard-line an ELECTRICAL 1/2 wave, or multiple
thereof, you will find the far end will repeat the impedance it sees
at the transmitter end. This is true of any impedance line, be it 72,
450, 1000 or whatever.
..........
but for my tribander that approach will obviously not work.  Any
ideas?
........
This is a little harder, but I would suggest you use the 50:75 ohm
transformer at each end. You could use any open wire line, again a
multiple of an electrical half wave, but you're going to have a
mismatch on 15.

Remember, the important thing is that an electrical 1/2 wave of any
impedance ( or multiple thereof ) will repeat what it sees at one end
at the other end.

Been using these things for well over 25 years. Work like a charm.

Good Luck
73
Ed