[Elecraft] KPA1500 Power Level

[Peter Hall]

Hello Barry,

I'm not a CW op but use my KPA1500 a lot at the sort of output levels you're interested in (for obvious reasons).  My operations are largely SSB, with the occasional JT mode digital on 160 m and 6 m.  I have not found the KPA1500 power output stability to be an issue, despite the fact that the efficiency is degraded.  The heatsink temperatures are certainly no worse than at higher power operation and the only real penalty is a small hip-pocket one when the power bill arrives.  On the IMD front my own quick measurements show that the overall picture is also no worse than at high power but it's not much better either, although the higher order products are a bit lower.

The KPA1500 manual is a poor effort for a premium product and, in areas like IMD specifications and any associated discussion, it's almost an exercise in studied disingenuity. An abiding irritation is the lack of a decent block diagram showing e.g. the connection points for signal and control lines.  In the end, the amplifier is a good one although given our antipodean locations, it'd pay to review the SPE and other offerings both in technical and support terms.  Personally, I like the Elecraft form factor and the relatively large amount of air in the two-box implementation.  My relatively early serial number RF deck has been back to the US once for service and upgrade and, while I was particularly grateful to a few Elecraft people for help at an obviously difficult time (CV19), the overall experience was very average.

73, Peter (VK6HP).



-----Original Message-----
From: elecraft-bounces at mailman.qth.net <elecraft-bounces at mailman.qth.net> On Behalf Of Barry Simpson
Sent: Wednesday, 15 September 2021 6:15 AM
To: Elecraft Mailing List <elecraft at mailman.qth.net>
Subject: [Elecraft] KPA1500 Power Level

I have had a quick look through the KPA1500 manual and could not find any reference to running the amplifier at a lower power level than the rated 1,500w.

Can anyone comment on the implications (eg temperature, efficiency and IMD) of running a KPA1500 at say 500w by simply reducing the drive power.

Would the power level be stable if set to 500w or would it drift upwards or downwards during the course of an over on CW ?

Thanks

Barry Simpson  VK2BJ
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