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50 or 75 ohm reference for analyzer?

Jan 6th 2013, 22:52

KO0Y

Joined: Apr 7th 2012, 19:22
Total Topics: 0
Total Posts: 0
I bought an antenna analyzer to scan my dipole's SWR. It can be set for either 50 or 75 ohm reference impedance. The initial line is 50 ohm LMR-400 coax, but that connects to a 4:1 balun, then 300 ohm twin line to the antenna. 300 divided by 4 is 75, so should I use 75 or 50 as the reference? I get significantly different results when changing. Thanks.
Jan 7th 2013, 13:56

W1VT

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0

Nearly all modern ham rigs are designed for 50 ohms, so you should use 50 ohms as the reference.

Zack Lau W1VT
ARRL Senior Lab Engineer

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