K2 KAT2 P-out readings?

[Joe Planisky]

I recently decided to give my K2 (#3490) a tune-up.  I hadn't done any  
alignment on it since I built it in June of 2003.  Realigning the  
bandpass filters produced a noticeable improvement in receive  
performance. I have the KAT2 antenna tuner option in it, so I re-did  
the bridge null and power calibration adjustments.

However, now I notice that the power output as indicated in the  
forward reading in "ATU Pout" mode is sometimes quite far off of the  
power set with the POWER control.   For example:

POWER  Pout
0.1    0.1
0.2    0.5
0.3    0.8
0.5    0.5
1.0    1.9
2.0    1.9
3.0    4.0
4.0    3.4
5.0    6.6
7.0    8.6
10.0  10.7
12.0  12.2

These are all into a known good 50-ohm dummy load.  I'm particularly  
concerned that requesting 0.3 W with the POWER control puts out more  
power than when I request 0.5 W.  Same between 3.0 W and 4.0 W.  I  
don't remember noticing this 6 years ago when I first built the rig  
(and I didn't make any notes to that effect in my log), but then I  
don't remember if I compared requested vs. measured power output back  
then.

I've checked continuity of the control cable between the KAT2 and the  
control board and all conductors are OK.  Before I dig deeper, I  
wanted to ask if these reading might indicate a problem, or is this  
just the nature of the beast?

73
--
Joe KB8AP

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[Don Wilhelm-4]

Joe,

Are you using the TUNE button when you make those measurements, or are
you doing CW and send 3 or 4 dots to assist in leveling the power and
then measure during a key-down period.
There is a difference. The K2 must have a bit of output before the power
levels out.  With TUNE, there are no breaks to level out the power and
you get whatever came up when the button was pressed - that will be
close, but try 3 or 4 dots of keying before measuring and I believe you
will find the power much closer and less erratic.

If the power does not then follow the power requested knob, tweak the
KAT2 forward power pot a bit - that is the indication of power output
that is being fed back to the K2 microprocessor.

73,
Don W3FPR


Joe Planisky wrote:

> I recently decided to give my K2 (#3490) a tune-up.  I hadn't done any  
> alignment on it since I built it in June of 2003.  Realigning the  
> bandpass filters produced a noticeable improvement in receive  
> performance. I have the KAT2 antenna tuner option in it, so I re-did  
> the bridge null and power calibration adjustments.
>
> However, now I notice that the power output as indicated in the  
> forward reading in "ATU Pout" mode is sometimes quite far off of the  
> power set with the POWER control.   For example:
>  
>

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