I would be more likely to suspect something after the KPA500, such as
the tuner or a balun. I've experienced significant balun heating,
especially when using a balun other than a straight-through 1:1 balun,
or when the load is highly reactive. Balun power ratings assume a
non-reactive load.
73,
Victor, 4X6GP
Rehovot, Israel
Formerly K2VCO
CWops no. 5
http://www.qsl.net/k2vco/
On 10/04/2020 14:26, 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.
73,
Alan. G4GNX
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