[Elecraft] Antennas and Output Power - KPA-1500

[K8TE]

No.  This is not the solution for what Pete describes and for what I and
others also experience.  Switching antennas, even antenna ports, often gives
very different power output numbers for the same drive levels from the
K3/K3S, even when appropriate and acceptable tuning solutions are found.

Using an external antenna switch on a single KPA1500 antenna port can be
problematic with the KPA1500 in cases where different tuning solutions are
necessary for different antennas.  Currently, there is no means to tell the
KPA1500 to use a different solution other than "trial and error" which means
providing RF on the "new" antenna, allowing the KPA1500 to find the proper
(trained) solution, change to that solution, and proceed.  At full power,
this process can result in an alarm which disables the amplifier,
inconvenient in the heat of battle (contest).

I have also noted that after not using the KPA1500 for a "long time" which
could be 15-30 minutes, power output can exceed alarm settings (well over
1500 Watts).  And when used some more, the power output decreases to 1500
without any exciter adjustments.  This means the KPA1500 gain figure seems
to increase after "resting" and decreases with use.

"Perfect" antennas that are always 50 Ohms and non-reactive won't cause
these symptoms.  I hope someday to have those.

73, Bill, K8TE



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