[TowerTalk] Using 75 Ohm Hardline

[Pete Smith]

At 12:43 AM 6/5/2005, K4SB wrote:
>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.


You don't have to use transformers, if the feedline is long enough  -- in 
my case, I cut for a full wave at 1750 khz, and the resulting cable is 12 
half waves on 15 meters.  A half wave on 80m is 6 half waves  on 15, on 40m 
is 3 half waves on 15.

I have been feeding a tri-bander stack with it for years.  Theoretically, 
frequency excursions at 10 meters can result in fairly substantial SWR 
fluctuations (as your operating frequency departs from the perfect 
half-wave multiple), but in practice I have not found any problems.

73, Pete