[Elecraft] KXPA100 Intermittent VSWR Issues

[Jim Brown]

On Sun,12/7/2014 9:19 PM, Jack Brindle wrote:
> Check for something arcing in the antenna system at higher power. This would be something that heats
> up before the arcing starts, like maybe a grounding RF choke on a vertical or something similar. The
> worst feedline component for this is the cheap right-angle UHF adapter. The center conductors are not
> well made, and will bend and arc to the shell over time. This usually is a problem at powers higher than
> the KXPA puts out, but it can still happen.

While I agree that these junk connectors can cause many problems that 
are difficult to track down, I'd be surprised to that spring overheating 
at 100W with a well matched antenna.  1kW, sure -- I had exactly that 
happen an hour into a contest running legal limit and calling CQ a lot.

But I certainly agree about avoiding these junk connectors. If it 
doesn't say Amphenol or have a MIL-spec number stamped into it, it's 
junk, and has no place in our stations. It can only cause us grief. I 
know that from direct personal experience -- when I got back on the air 
in 2003 after a couple of decades off, I restocked my box of parts with 
all sorts of these el cheapo adapters -- Tees, barrels, BNC to UHF, to 
N, and so on. Over a period of three or four years, I experienced more 
than a half dozen flaky failures that were hard to track down, all due 
to those junk connectors.

73, Jim K9YC