[Elecraft] K2 Transmitter and KAT2 failures

[Don Wilhelm]

Damon,

I would speculate that you have bad diodes in the KAT2 wattmeter (D1 and 
D2), or there is some other problem with the wattmeter in the KAT2.

Try this test:
1) Put an external wattmeter (or other power measuring device) on the 
output of the K2 and make certain you are connected to a good 50 ohm 
dummy load.
2) Set the power to 4 or 5 watts and set the KAT2 to CAL P and press 
TUNE - check to be certain the K2 is controlling the power output near 
the requested level.
3) Evaluate the result:

If the power goes to maximum output (but displays 0.1 or 0.2 watts - 
which is actually zero), then you have a problem with the KAT2 wattmeter 
circuit, and it it was working before, the most likely cause is that the 
diodes have been zapped.

OTOH, if the K2 display shows some reasonable power output, but is quite 
different from the external wattmeter, you need to calibrate the KAT2 
wattmeter - start with the balance adjustment, then calibrate the power 
output and finally calibrate the SWR.  The adjustments must be done in 
that order - if you go back to a prior adjustment, you have to re-do the 
other adjustments.

Fact is you may have only the forward diode bad but not the refl diode - 
that would cause a higher than normal SWR to be indicated.  Since the 
diodes were likely damaged by a lightning static surge (yes, it can 
happen even with an attic antenna), I would recommend replacing both of 
them if either are suspected of causing a problem.

73,
Don W3FPR

Damon - KC5CQW wrote:
> Below is some of the text that I sent to Gary. 
> Basically, if I use the KAT2 to tune my 40m attic dipole the PA finals will
> short out. 
> I haven't tryied to tune any other antennas because I don't want to pay for
> any more PA kits ($18.50 'ish each time I tune up).  
> Also, CW is un-usable above 80m and no CW output on 10m (SSB and "tune"
> yield 8.5W)
>
> See text below...
>
> 73, Damon KC5CQW
>
>