K2 & KPA100 Problems.

[Bob Wehking]

I am now at the final checkout of my KPA100 & on page 47, there was an addendum to measure the voltage at the left side of R12. In the CW test mode, the voltage should be between 100-110 VDC while in the tune mode. I get zero.

I hooked up a LDG digital wattmeter & when I set the rig for 5 watts, I get 10 watts, radio readout shows 5.6 & swr 1.0:1. When is set the radio to 10 watts, the radio shows 10 watts but the watt meter show 20 watts. When I adjust the power for 20 watts, I show 26 on the radio & 39 watts on the watt meter. From that point on, no matter what power setting I set, my power out stays around 40 watts on the watt meter  on all bands & the radio shows 28watts. As I turn the power adjust to 70 & above, the output power drops to 30 watts on the wattmeter, still26 on the readout.

Any idesa why the power adjust on the basic K2 causes the K2 to put oot twice that of what is showing on the screen. Secondly why I don't have a reading at R12 & lastly why I can't get bore that 40 watts output?

Thanks
Bob
WB8DDI
K2 #4998
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[Don Wilhelm-3]

Bob,

To answer your power output discrepancy question first - the wattmeter in
the KPA100 must be properly calibrated before it will read correctly.  If
you can trust the calibration of your LDG, you can set the KPA100 wattmeter
to match that reading.  The instructions are in the manual.

BUT, your first problem to tackle is the lack of voltage at R12.  If there
is no voltage present there during transmit, the TR switch will not work
properly and that could certainly explain your max of 40 watts output.

Do you have negative voltage on U4 pin 8?  It is usually more negative than
20 volts. If you have voltage there and none at R12, there is either a short
to ground somewhere or there is something wrong with the high voltage bias
supply.  Look at the schematic (sheet 2) and identify the diodes and
capacitors in the HV Bias Supply and check each one of them for proper
orientation and soldering.

73,
Don W3FPR

> -----Original Message-----
>
> I am now at the final checkout of my KPA100 & on page 47, there
> was an addendum to measure the voltage at the left side of R12.
> In the CW test mode, the voltage should be between 100-110 VDC
> while in the tune mode. I get zero.
>
> I hooked up a LDG digital wattmeter & when I set the rig for 5
> watts, I get 10 watts, radio readout shows 5.6 & swr 1.0:1. When
> is set the radio to 10 watts, the radio shows 10 watts but the
> watt meter show 20 watts. When I adjust the power for 20 watts, I
> show 26 on the radio & 39 watts on the watt meter. From that
> point on, no matter what power setting I set, my power out stays
> around 40 watts on the watt meter  on all bands & the radio shows
> 28watts. As I turn the power adjust to 70 & above, the output
> power drops to 30 watts on the wattmeter, still26 on the readout.
>
> Any idesa why the power adjust on the basic K2 causes the K2 to
> put oot twice that of what is showing on the screen. Secondly why
> I don't have a reading at R12 & lastly why I can't get bore that
> 40 watts output?
>
> Thanks
> Bob
> WB8DDI
> K2 #4998
>

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