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Old November 15th 06, 06:36 PM posted to rec.radio.amateur.antenna
Tam/WB2TT Tam/WB2TT is offline
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First recorded activity by RadioBanter: Jul 2006
Posts: 125
Default matching 50 ohm line to 75 ohm antenna


"N4aeq" wrote in message
ps.com...
Im trying to match 50 ohm coax (lmr400) with a log peroidic which
should have a 75 ohm feedpoint
the SWR is flat across the 6 m band but high. Im thinking i need a
better match but not sure
where to start.

I can't remember the numbers, but there is a procedure in either the ARRL
Handbook, or antenna book for doing this. Basically, you have a short piece
of 50 Ohm coax, a short piece of 75 Ohm coax, and then an arbitrary length
of 50 Ohm transmission line.

If the antenna is 75 Ohms, your SWR on the 50 Ohm line should be no more
than 1.5:1. Are you sure you don't need a 4:1 balun? If your SWR is around 3
or 4, I would try the balun; easy neough to make out of a 1/2 wave piece of
coax.

Tam/WB2TT