PGXL swr protection question

Mike

I have a 6600 and PGXL. My antenna is just a simple dipole and the swr is low less than 1.5 to 1. Up until today now problems with using the PGXL on 80m (cw and FT8). Today for some reason the amp starts out xmit or and then shows high swr for some reason, folds back and stops transmitting. taking the amp out of line the radio is just fine xmit 100w into the antenna. I wonder what has changed or what I may need to reset.

David Decoons, wo2x

I had a problem with an old wire antenna that used 450 Ohm ladder line with solid conductors. Over time in the wind the conductor broke but the insulation was intact. At 100 watts it was fine but at high power the SWR would jump.

I replaced the ladder line with copper clad steel stranded ladder line by David RF. I also switched to copper clad steel stranded insulated wire for the antenna. No more issues.

The other thing it may be if you have a balun it might be heating up.

73

Dave wo2x

Mike

I'll check some of that, thanks. Just odd that it worked fine up until yesterday.

Bill NE1B

I had a similar problem. On Low power I had 1.6:1, then with the amplifier the SWR went up over 2:1. I reduced power and all was fine. Then one day SWR on low power went to 10:1. I lowered the antenna to check the connections and found the OCD 4:1 balun box had melted! I opened it up and found tiny spider nests inside! They came in thru the downward facing "weep hole".

There are so many possibilities including RFI into the shack LAN cables which would protect the amplifier by putting it into alarm.

73,

Bill, NE1B

Mike

Thanks, turns out to be a bad coax