With the KPA3A / 100 watt amp active, which switches in at 12 watts, the
LPA then runs about 1 to 5 watts. The issue I encountered was running
the KPA3A / 100 watt amp, at the lower end of the power range being 15
or so watts. I encountered two failures of the KPA3A amp module.
I now stay away from that power level thus running 20 to 25 watts from
the KPA3A. I've been doing this since May 2018 when the last KPA3A was
replaced. I was also advised by another ham who experienced several
KPA3A failures to "stay away from 15 watts". The last KPA3A is the Rev E
model that, according to the report from Elecraft, states "Replaced
KPA3A Rev B with the more stable KPA3A Rev E amp".
The discussion can be confusing as the LPA runs normally up to about 12
to watts but can be pushed to near 15 watts. The KPA switches in the
circuit at ~12 watts. {Listen for the relay click} General discussion
surrounds running the LPA at 12 to 15 watts in high duty cycle modes,
thus causing failure of the LPA. The devices are only heat sinked to
the bottom panel and no forced air cooling is provided for the LPA.
73
Bob, K4TAX
On 11/22/2019 7:08 AM, hawley, charles j jr wrote:
I thought the answer was to run the KPA by going up to 12 or 15 watts. What is
the LPA running when when the power is at 12 or 15 watts? What is it running
when the power is at 20 or 25 watts?
Chuck Jack Hawley
KE9UW
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