Effects of using 75 ohm cable (coax collinear antenna)

[tickingmind]

I built a coax collinear antenna a while ago to pull in a faint radio station and it has worked well, two 1/4 wave lengths, all 75 ohm cable for construction down to my receiver. The antenna is now retired as I replaced it with a Yagi since a competing station was causing some issues (Good airwave management don't you think?)

Now my friend has the antenna and has been broadcasting for some time off a wire horizontal dipole, He wants to use the collinear but the question was raised about the impedance. His TX is 50 ohms. The antenna is 75 ohms. What might be expected in the sense of power loss due to the mismatch?

Thanks,
TM

[Slim Jim]

Can't speak for the 75 ohm coax but the antenna impedence is almost the same as a standard dipole.

Simple suggestion is to use 50 ohm coax.

[tickingmind]

Thanks. He has now tried it and the SWR is a little high, about 2.8:1
He trimmed it and now it is even higher. I suggested trying 75 ohm cable on low power and he is going to do that.

[Slim Jim]

Maybe the antenna needed to be lengthened instead of trimmed? Look forward to finding out what happens next.