"PDRUNEN" wrote in message
...
Hi Group,

Have a MFJ-269 here (new toy) and did a bit of expermienting with the TV
antenna over the Christmast weekend, I have one of those 13 element
antenna
from radio shack, I don't know the exact part number.

I tied the MFJ-269 into the 300 ohm to 75 ohm balun at the antenna. The
antenna being about 20 feet up on the house peak.

Looking at the impedances I got, nothing really looked good at the TV
frequencies as I would have expected.

If the match is this bad, I would expect alot of loss from the fact that I
run
75 ohm cable down from this antenna to the TV set.

Could my reading be mis-leading since the balum is a 4:1 going from 300
ohm to
75 ohm?

Has anyone done this before and posted the data? I would be interested to
see.

I don't have my data in front of me at this time so I don't have any
measurements to post.

I really find the MFJ-269 an exceptional device for the antenna
experimenter.

Tnx de KJ4UO


You will want to measure Z, not SWR. My offhand guess is that impedances
between 25 and 225 Ohms are about as good as you could expect. There will
probably be at least one frequency between channels2 & 6 and one between
channels 7 & 13 where you get some R + j0.

You might also want to put the MFJ in the mode where it displays parallel R
& X. It might show more of a trend.

The antenna not being 300 Ohms does not result in high SWR loss in the coax.
Your receiver not being 75/300 Ohms would. This is the inverse of the
transmitting case.

Tam/WB2TT