[Elecraft] KPA500 - Full Power Keydown

[Jim N7US]

I keep my KAT500 under my KPA500 to not impede the airflow from the
amplifier, as recommended in the manual.

73, Jim N7US



-----Original Message-----

The KPA500 RF deck and power supply can put out 500 watts for a very long
time (definition of "very long time" is an exercise left for the reader).

If you are operating outdoors in direct sunlight in Saudi Arabia at mid-day
in the summer, key down time is likely limited to a few minutes.  If the
heat sink is covered in dust from a recent wind storm, it may only be
several seconds.

If you are operating at the south pole in winter with a direct air duct to
the outside to draw cooling air over the KPA500 heatisnk, you can probably
operate key down for months -- and might need to to prevent the amplifier
from being damaged by the extreme cold!

The point is that this is a thermal management problem.  If you keep the
ambient air environment around the amplifier at a comfortable room
temperature and ensure the fan and vents on the amplifier cabinet are not
blocked, you can probably operate it at 500 watts as long as you have
patience to hold the key down.  If the ambient air is not sufficient to cool
the power transistors, perhaps due to temperature or limits on air flow, the
amplifier will eventually shut down to protect itself.

Like many things in life, this is a system (ham shack station design
including physical environment) issue, not a component (amplifier) issue.

73,

Lyle KK7P

> May be I would like to ask the question from another angle.  Can KPA500 be
used for RTTY in a contest condition say at 500W?  If not, do we need to
turn it down to 300W?