I thought that one of the features of the K3/K3s was that it was able
to run, and run well, off of batteries. These power spikes makes it
sound like that is not the case? Or am I missing something?
Batteries start out at 12.6v and go down from there. The K3/K3s needs
to run well down to something like 10.5 to 11v. But if they need at
least 13v to prevent power spikes . . . .
73 de dave
ab9ca/4
On 3/1/16 9:30 AM, Don Wilhelm wrote:
Bill,
Is there any way that you can increase the power supply voltage to
13.0 volts or more during transmit? If so, that should help.
Most of my experience with power control is with the K2 which starts
out at lower than the requested power after a band change or a change
in power level, but quickly builds up to the requested power. The
result is a lack of power spikes.
I figured that the K3 power control is similar, and if so, I would not
expect power spikes at all. Perhaps the power control loop should be
investigated for critical damping. If power spikes occur, that is an
indication that the control loop is underdamped.
If the control loop damping is the problem, it is possible that this
is not a problem for all K3s - the loop gain will may vary depending
on the gain of the transmit RF stages, and while one K3 may have this
problem, another may not (that is the case with the K2). The RF Gain
also varies from band to band, so there may be a difference in that
behavior depending on what band is used.
73,
Don W3FPR
On 3/1/2016 10:12 AM, Bill Hammond via Elecraft wrote:
Hi John,
My power dances all over the place (my serial number is 00069).
Just had a quick QSO with the KPA500 indicating 560 watts at the
beginning and then going down to 480 at the end. That is typical.
My 12 volt supply drops to 12.2 on transmit, 13.3 on receive. I
have a long 12 volt cable from the supply so “I" squared losses
are understandable in the cable. Driving power from the K3 is
variable per band but typically set to 25 watts or so. The QSO
described above was on 17 Meters and the drive is 25 watts there for
~500 watts out or just below after stabilization.
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