> Is there a solution for matching 75 ohm hard-line to a triband
> antenna?
>
> I have a 6 meter, 2 meter and 440 antenna on my tower with 100 ft of
> 9913 feeding it. At 440, it's probably about 6 dB loss. I would
> like to replace the bulk of the line with 75 ohm hard-line. I know
> that you can match the impedance with tuned matching stubs, but that's
> difficult to do with 3 different bands at once...
You could just feed it with the 75 ohm cable, the SWR on the 75
ohm cable will only be 1.5:1.
Keep in mind the 50-ohm normalized SWR would be as high as 2:1
on some frequencies with 50 ohms at the far end of a 75 ohm
cable. Because of that, you want to do two things:
1.) Pick a length of 75 ohm cable that does not result in the worse
impedance showing up at the 50 ohm cable connection point at the
transmitter end.
2.) Never randomly mix 50 and 75 ohm cables in the system
*unless you are doing it for a good reason*. Just make one 75 ohm
length, and keep the rest of the system all 50 ohm cables.
73, Tom W8JI
W8JI@contesting.com
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