[Elecraft] K2/100 #2700

[Tom Hammond NØSS]

Michael:

>During my test and alignment phase, I noticed that when setting the power to
>11 Watts with the PA on, the voltage display drops to 8.5V, 3.4-3.5A and 
>the fan comes on immediately.  When returning briefly to the tune mode, 
>the fan slows down as if the voltage feeding it drops but returns to 
>normal speed when I exit the tune mode.  There are no error codes in the 
>PA menu.

It sounds as though your power supply is having problems supplying the 
required amount of current. Sounds as though the supply is going into 
'foldback' mode.

The fan may well turn on when the PA is enabled... especially if the 
setting for TPa is not set properly.

Originally, when I set TPa, I forgot to CONVERT Farenheit to Centigrade, so 
this caused the fan to turn on ALL THE TIME.

Ensure that TPa has been (fairly) accurately set, and that the FAN 
parameter is set to NORmal, otherwise, the fan will run at one speed or the 
other any time the PA is enabled.

>I have a feeling that the power transistors have been damaged somehow but 
>further checks will have to wait until I get home Saturday.  For now I 
>have the PA turned off and will continue at QRP power levels until I 
>figure out what the problem is.

Look to the power supply and TPa first.

>Another thing I have noticed is that while in tune mode with the PA off, 
>the power reading on the LCD says I have an output of about 16 Watts but 
>my external Wattmeter reports less than 10. Also the LCD display reports 
>just over 12V but only about 1.8A.

You're still using the KPA100's wattmeter circuitry... better check your 
calibration.

>With the exception of the power output problem with the KPA100, all the 
>other tests are okay (I haven't gotten to the the voltage checks on the 
>board yet).
>The radio "talks" to the computer via K2 Remote and N1MM logger without any
>problems.

I kinda doubt you have as many real 'problems' as you might think you do.

GL OM,

Tom Hammond   N0SS