Hi Jim,
I've experienced a 10% drop in output as the finals warm up, which
doesn't ultimately make a large difference, but can be compensated if
desired (a percentage of 1 dB).
It can run legal limit on all bands; but into a SteppIR, because of the
transformer/balun in play not being efficient at 6M, limit the output to
no more than 1 KW (ask me how I know).
I use the default speeds, but I'm also uncomfortable with it going above
65C, so I step in at that point and boost the fans.
73,
Rick nk7i
On 11/10/2023 11:34 AM, Jim Brown wrote:
I've been told by someone who knows that 1) it is normal for MOSFet
devices to lose efficiency as they heat; 2) the KPA1500 can run WSJT
modes at rated power except on 6M, where it's best to not run much
more than 1 kW for long TX sessions, like meteor scatter. It's an
issue un-related to the the MOSFets; and 3) to use default fan
settings and let the amp adjust upward as needed.
73, Jim K9YC
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