Chris,
I cannot answer how well the KPA500 will run when driven 1 to 5w, but
JT65 does NOT require a linear amp. It runs the same as CW, only
stepping in frequency (makes different tones in a SSB receiver), so
one can use a class-C amp if they want to with JT65.
Therefore, there is no concern about intermod distortion (any more
than if one ran CW).
How efficient the KPA100 runs when lightly driven is another topic
which I cannot answer. It does reason that the heat sink should
easily take care of the heat at 50w, if designed for operation at
500w. If the KPA500 runs in class-AB it will dissipate some minimum
level without RF drive. If it were class-A it would dissipate full
power all the time.
I run my 8877 far into class-B so there is almost no idle current
without drive. In class-C it would be biased at cutoff.
One might measure the current draw without drive, but often much of
this is attributed to digital control components that have nothing to
do with dissipation of the finals. Perhaps the Elecraft engineers
have that number?
73, Ed - KL7UW
Date: Thu, 18 Jul 2013 15:08:14 -0700
From: Chris Johnson <[email protected]>
To: "[email protected] Reflector" <[email protected]>
Subject: [Elecraft] [KPA500] Low Power Use Cases
Message-ID: <[email protected]>
Content-Type: text/plain; charset=us-ascii
I love my KPA500. I don't use it enough because of all the low power
digital I do. I was wondering if the quality of my signal would
better if I let the KPA500 produce the output even if the wattage is
50 or less watts. If I drive it with 1 to 5 watts, it produces 10
to 50 watts. I like the thought of offloading the thermal load of
my long JT65 & JT9 duty cycles onto the KPA rather than my main rig
which is a Flex 6700.
Does the KPA500 make a much cleaner signal than the built in barefoot
amp because its running at such a higher voltage? I'm not too
concerned about power efficiency comparisons, because we know its not
more efficient doing it this way. :)
Thx
-Chris
73, Ed - KL7UW
http://www.kl7uw.com
[email protected]
"Kits made by KL7UW"
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