[Elecraft] K2/KPA100: External Amplifier Keying Test (PA Key) Problem

[Don Wilhelm]

Hideki,

With power off, check the resistance from the source of Q9 to ground.  
If you can check from the lead of Q9 rather than the solder connection.  
If it is not zero ohms, you have a soldering problem there.

If the source of Q9 is well grounded, next check the voltage at the Q9 
gate during TUNE - it should be in the 3 to 5 volt range. - if lower 
than that, check the soldering and value of R1 and the soldering at U1 
pin 16 (pin 16 of U1 should be very near 5 volts during TUNE).

If all is good with those checks, Q9 itself is the prime suspect (but I 
have never hear of one being a problem).

73,
Don W3FPR

JF1KGX wrote:
> Somebody has asked the same before. But nothing has been replied.
> Now I have the same problem.
>
> Page 49 of the KPA100 instructions calls for testing the resistance between
> ground and the tab of Q9 on the KPA100 board (or center conductor of the PA 
> KEY
> output jack, J7).
>
> According to the instructions, the resistance should drop to less than 3 
> ohms
> when the K2 is put into TUNE mode.  Mine only drops to about 270 ohms.  The
> troubleshooting in the KPA100 manual doesn't even include any information 
> for
> what to do if the resistance doesn't drop to less than 3 ohms.
>
> So far everything else seems to be working correctly with the KPA100.
> My serial number is 06617.
>
> Please advise me.
>
> Thanks
>
> Hideki
> JF1KGX
>
>
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