Antenna or KAT500/KPA500 Problem
Posted by
Elecraft mailing list on
Aug 07, 2019; 2:00am
URL: http://elecraft.85.s1.nabble.com/Antenna-or-KAT500-KPA500-Problem-tp7654300.html
Every so often at random after I have been on SSB for a while ( 80m with about 450w and a 1.1 to 1 SWR) my tuner jumps to retune or the amp faults and switches to standby. I am using a Van Gorden full size (102’) G5RV as
an inverted vee. The 31’ matching section is 300 ohm twin lead and, even though it has been up for 10yrs, is still flexible. Van Gordon is now out of business. The twin lead goes into a 3/4” pvc pipe and coax comes out the other end.
I am thinking that the 12” long pipe section has ferrite beads to cut common mode currents. I don’t know what wattage the ferrites are rated for.
Someone suggested that the ferrites might be heating up and causing my problem since the problem occurs after being on the air a while and could be thermal.
My questions are:
I have some new 450 ohm ladder line. Should I replace the 300 ohm with it? I know that most G5RV’s on the market today use 450 ohm not twinlead. If so what kind of line isolator is needed or what balun? Should I just replace the ferrite beads — and if so with what no. and mix. Can I just use an ugly balun (coiled coax). All thoughts are appreciated. The antenna itself has worked fine for me on all bands (80 thru 10) and I have worked all continents except Antarctica. Thank you in advance and 73 Mike KF6KXG
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