[Elecraft] K2/100

[Andrew Lenton]

See comments on brackets  
  
  KR 
  
  
  
  
  Andrew  
  
  
  
  
  
  
  
  
  
  Andrew, 
  
  
  
  
  With the KPA100 installed, and the power set to 10 or 11 watts, what is  
  
  the actual power output in TUNE? 
  
  It should be near 2 watts. (True this is fine.) 
  
  
  
  
  If not, there is a problem in the VRFDET section of the KPA100 or in the  

  
  base K2. 
  
  First, remove the KPA100 (physically) and try it with just the base K2. 
(Works fine) 
  
  
  
  
  If the base K2 is OK, then yoou have some KPA100 problem to solve.  Put  
  
  the KPA100 upside down on a box or book about 1/2 the height of the K2  
  
  and remove the shield. ( All done works fine) 
  
  
  
  
  set the power to about 50 watts and prepare to do some voltage 
measurements. ( 50 Watts set up) 
  
  
  
  
  (I will do this) 
  
  
  
  
  Measure the voltage at U5 pin 5 - then at 5 pin 7, they should be close  
  
  to the same voltage. 
  
  U6 pin 3 should be about 1/2 that voltage.  If not, the problem is Q10  
  
  
  
  
  ( Only see the problem after I put the PA back on the  K2) 
  
  
  
  
  
  
  
  and possibly Q11. 
  
  
  
  
  If all OK this far, then make certain U6 pin 8 is near 5 volts. 
  
  If so, then check U6 pin 6 and tell me what the voltage there actually  
  
  is.  U6 is a common failure. 
  
  
  
  
  73, 
  
  Don W3FPR 
  
  
  
  
  On 7/26/2026 1:16 PM, Andrew Lenton via Elecraft wrote: