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

Bill Roberts

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?

EA4GLI

Looks like you might be txing out of the wrong ANT port.

G4NRT

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

David G4NRT

Martin AA6E

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.

Bill Roberts

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.

Bill Roberts

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.

km9r.mike

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.