K2

[K6KYJ]

I have a fairly old K2/100AT. It was in deep storage for a year. Friday I took it out of storage for CQP and ran it through some basic tests on a dummy load. I then went on the air on 20, 40, and 80 meters that evening on separate tuned dipole antennas with SWR better than 1.5. All operations were nominal and power output was 100 watts or less.
Saturday morning, upon powering up, I received error messages of HIGH eFL and PA HOT.  I went to low power and confirmed a good SWR. I then went to a dummy load and attempted to bring power up to 100 watts. Nearing eight watts or so, the error messages reappeared. Removing the AT from the system made no difference.

Tonight, I resumed tests and it appears that if I keep the power at five watts the rig will operate okay.  Wonderful.  I can work TX3X as QRP.
I am not an EE.  I think I am a notch above appliance operator, however, and my summation is that the PA went south on me.  If so, it has faithfully served its masters.  The rig was previously used by AD6E on several expeditions (and Al is currently using a KX3 as one of the TX3X ops).
Any feedback would be appreciated.

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[Don Wilhelm-4]

Ron,

First the PA HOT message -- power off the K2 and let it rest for 30
minutes to acclimate to ambient temperature.  Then power it on and enter
the menu for CAL TPA.  Edit the parameter and rotate the VFO knob to set
the value at the ambient air temperature in degC.

After that, check on the HiRefl message.  If it is still present, the
most likely problem is that the KPA100 wattmeter diode D17 has been
damaged (usually a result of static coming in on the antenna feedline).  
Replace both D16 and D17 while you have the KPA100 disassembled - they
are 1N5711 Schottky diodes.
There could be problems other than a faulty D17 diode, but that is the
most likely cause.

It is very unlikely that the PA transistors are at fault for that problem.

73,
Don W3FPR

On 10/8/2015 11:38 PM, Ron Angle wrote:
> I have a fairly old K2/100AT. It was in deep storage for a year. Friday I took it out of storage for CQP and ran it through some basic tests on a dummy load. I then went on the air on 20, 40, and 80 meters that evening on separate tuned dipole antennas with SWR better than 1.5. All operations were nominal and power output was 100 watts or less.
> Saturday morning, upon powering up, I received error messages of HIGH eFL and PA HOT.  I went to low power and confirmed a good SWR. I then went to a dummy load and attempted to bring power up to 100 watts. Nearing eight watts or so, the error messages reappeared. Removing the AT from the system made no difference.
>
>

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