[Elecraft] K2 Transmitter and KAT2 failures

[Damon - KC5CQW]

     Well I did it again, My last set of finals just fried! I was using my
manual tuner on 20m at 2W.
I think what's happening is the power spike is overloading the finals at the
end of each transmission.
Now I no longer believe the KAT2 is responsible since it was out of circuit.
I have not been able to find any faults in the KAT2. It just seemed a likely
candidate because thats when the failures would occur.
I've now proven that theory incorrect. I must have a fault in the LPF or PA
sections. To date, I have not been successful in locating the problem. 
     It is long overdue for me to swallow my pride and send the K2 in for
service. I think what hurts the most is knowing that it will be something
simple like a bad solder joint. 
I want to thank Don and the everyone else that has helped me to this point.
In the 2 1/2 months i've owned this radio, I'm glad to say that at-least I
did make one contact on the air! 

73, Damon KC5CQW



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
> 
> Copied text from support email:
> 
> On 40m-10m when I release the CW key or mic PTT in CW mode, the moment it
> is released I get a power spike resulting in a HiCur warning.
> On 12m and 10m I have no output during key down; Only the power spike. (CW
> only, SSB is fine)
> If the tune button is activated, The radio will give about 11w Max on 12m
> and 8.5w on 10m.
> All other bands yield 12-15W max.
> 
> 
> At the time of the last PA meltdown, I was able to tune my 40m dipole on
> 80, 40 and 10m; It failed at 30m.
> There seems to be no rhyme or reason as to when a failure will occur. It
> has happened at different frequencies.
> I am reluctant to use the KAT2 except in bypass from this point on. 
> I don't seem to have any problems with my MFJ-969 Versa Tuner II. 
> 
> During some KAT2 troubleshooting, I found that the voltage on pin 1 of U4
> was about 2.5VDC (3-4V spec at 5W) with a leg of R6 lifted.
> Perhaps I'm not having a mechanical short on the LC board. Maybe the
> SWR/Power bridge is sending the wrong data.
> If I tune up on 10m into my dummy load, the K2 reports a 2.1:1 SWR. My
> MFJ-969 read 1.05:1
> 
> The best I can tell, everything seems to be fine on the SSB modes. I can't
> help but think however, if a problem in CW if occurring that I may have
> some distortion on SSB.
> 
> 
> 


-----
Damon Wascom KC5CQW
Elecraft K2 #:6351
Build: 12/28/07-01/01/08


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