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Need help on How to test transmission line

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June 26th 06, 12:44 AM posted to rec.radio.amateur.antenna

Dave

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Need help on How to test transmission line

wrote:

Hi fellow amateurs,
I am using 746Pro for 6M with direct coax to my 5 el antenna. I used to
get 1:1 SWR but recently, the SWR runs a little over 1:2 and my output
drops to 30W.When stations in FN20 were working EU, I could hear
nothing. My signal can still be received because I was able to make
contacts despite 1:2 SWR as far as FM5AA. But I know something is wrong
with the line or the antenna. I checked all the connections and they
seemed to be ok.

Can someone help by directing me to a source where I can read about
troubleshooting transmission line? Or can someone who has experience in
this give me step by step instruction on how to diagnose the problem,
e.g., is it the PL 259 at the rig side, or the antenna side, or
somewhere along the line, or is it the antenna altogether. I have an
ohm meter and a small swr/pwr meter box.
Thanks in advance.

73, steve

Steve, If you can locate someone who owns an antenna analyzer you should be able
to analyze your problem. I use the MFJ 259B.

Someone in your local radio club should own one, antenna analyzer, or have
access to one.

BTW, a 2:1 VSWR is not BAD. It indicates that the antenna is receiving 90% of
the available power. However, ICOMs are designed to power down on low to
moderate VSWR. Note: I run about 30:1 on 75 meters.

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