In my experience, coax connectors, barrel connectors, etc. are always fail
points when there is a sudden increase in SWR as power is increased. They
> Alan,
>
> That does sound like an antenna problem - balun heating, a loose or bad
> connection somewhere.
>
> Try that same test into a dummy load - if it shows the same behavior,
> then you can blame the KPA500, but if not blame the antenna system.
>
> 73,
> Don W3FPR
>
> On 4/10/2020 7:26 AM, Alan - G4GNX wrote:
> >
> > I have a strange fault a couple of times recently, where the SWR starts
> > to increase during the time of a single 'over'. I've been using the K3S
> > set at 100W out, via the KPA500 (in standby) and the KAT500 tuner,
> > without any problem, but after I've switched the linear to Operate and
> > driving it to 200W, the SWR creeps up. I don't think it's an antenna
> > issue, but a possible heat problem with the KPA500. I watched the
> > temperature display on the KPA500 and initially on Standby it shows
> > about 38 degrees C. After transmitting at 200W the temperature slowly
> > rises above 60 degrees C, but the fan doesn't cut in. Does anyone know
> > if this is normal behavior and what temperatures I should expect to see?
> > I have tested the fan via the Menu function and it works as expected.
> >
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