Unexpected Behavior of Smart SDR SWR / Power Meter into New OCF Dipole

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  • Updated 4 years ago
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Today I installed a Maxcom (fairly generic) OCF dipole for 80-6 meters.  It has the supplier's 4:1 balun.  I have made a choke at the feed point from a 3 inch ferrite doughnut with 12 turns of RG8X coax followed by 5 snap-on split beads of admittedly unknown mix (Amazon).  My MFJ 259C analyzer says 1.2:1 SWR on 40 meters.  The feed point is about 40 feet above the house and not directly over the shack.  My "Flex PC" has a pair of $8.99 amplified speakers that pick up virtually all stray RF.  They are quiet.

Given the above, my back-up rig, an IC 7300 operates normally into the antenna.  At least on 40, my Flex 6300 running SSDR 1.18.4 shows off the scale SWR and little power output.

Any ideas?
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Bill Roberts

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Posted 4 years ago

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Photo of EA4GLI - 8P9EH - Salvador

EA4GLI - 8P9EH - Salvador

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Looks like you might be txing out of the wrong ANT port.
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David G4NRT / Z21NRT

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I think we have ALL done that - once at least!

David G4NRT
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Martin Ewing AA6E

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My 6500 occasionally transmits into an open circuit, it seems.  Somehow the internal antenna switching does not set up properly.  I can fix this by switching antenna ports to #2 and then back to #1, or other fiddling like that.  After it starts working, all is normal.

It's rare enough that I haven't declared it to be a major problem, but it is a nuisance when it happens.
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Bill Roberts

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I'll give that a try.  The funny thing is that I do receive.  Signals seem about 20% weaker than on my main antenna (a GAP Voyager vertical dipole for 160-20).  Thanks.  I will report back but first I have to do the lawn.
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Bill Roberts

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Official Response
Might as well close this one. It appears my problem was stray RF that didn't bother the back-up radio. Problem resolved with an old Radio Works line isolator.
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Odd that your pc speakers which seem to be both sensitive and accurate to the presence of stray rf did not indicate such. Good to hear you found a solution and did not have to rely on that back up rig.

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