setting power via RS232 with KPA100

[Brian Mury-3]

I've discovered some odd behaviour when setting the power level via the
serial port on a K2/100.

The front panel power knob changes between the K2 PA to the KPA100 PA
depending on the power level (it switches at 10 W).

When setting the power via the serial port using basic mode, whichever
PA is in use will remain in use, regardless of the output set via the
serial port. The K2 will not switch according to the power level like it
does with the front panel knob. This means:

- If the K2 PA is in use (power is set to 10 W or less with the front
panel knob), then power cannot be set above 15 W via serial.
- If the KPA 100 PA is in use (power is set >10 W with the front panel
knob), then power can be set as low as 1 W, but it does not switch to
the K2 PA.

This seems like rather odd behaviour to me (and it isn't documented,
BTW).

When setting power via the serial port using extended mode, either range
can be selected, so the output can still be set as low as 1 W with the
KPA100 PA.

I'm planning to use extended mode so that the computer can set the power
to >15 W regardless of the front panel knob. Should I:

A. switch to the K2 PA below some value? (and if so, what value? 10W? 15W?)
B. always use the KPA100 PA, even for low power settings?

I'm leaning towards A because of the better resolution (0.1 W steps
instead of 1 W), but I'm curious if there are any reasons why the KPA100
PA should or should not be used at low levels.

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[VR2BrettGraham]

VE7NGR noted:

>When setting the power via the serial port using basic mode, whichever
>PA is in use will remain in use, regardless of the output set via the
>serial port. The K2 will not switch according to the power level like it
>does with the front panel knob. This means:
>
>- If the K2 PA is in use (power is set to 10 W or less with the front
>panel knob), then power cannot be set above 15 W via serial.
>- If the KPA 100 PA is in use (power is set >10 W with the front panel
>knob), then power can be set as low as 1 W, but it does not switch to
>the K2 PA.
>
>This seems like rather odd behaviour to me (and it isn't documented,
>BTW).

I would suggest this is a nature-of-beast issue.

One must leave RIT knob centered, otherwise clearing it by
remote control results in RIT going back to where knob is
pointing (I drive RIT up & down by remote).

Makes sense when you think about how the knobs are read.
No idea if the reaction is immediate on return to receive (didn't
bother to check), but display changes on next update.

73, VR2BrettGraham

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