[Elecraft] KAT100 Power Calibration at R4-help!

[Gil Stacy]

No joy during power calibration.  On my KAT100, I’ve completed the initial 
tests involving the LED sequences, the Menu and Relay tests and all appears 
fine.  However, after completing the SWR Bridge Null Adjustment at 10mV and 
then moving to the Power calibration of R4, at pin 5 of U5, with 20 watts 
out of my K2/100, I only detect a range of mV (app. 100-20) on my DVM—no 
where near target of 2.7 V.  My set up is dummy load (15w) on RF In and coax 
from K2 to ANT1 on KAT100 with the control cable (K2 and KAT100) and power 
cable to the KAT100 removed.  In accord with manual, before power was turned 
off at K2 and KAT100, , K2/100 was set to CAL mode and Menu exited prior to 
shutdown. The power level of the K2/100 is set at 20 watts.  In “TUNE”, the 
K2’s LCD registers HiCurr and then 9.9-1.  With the K2/100 set at 20 watts, 
at the KAT100’s  Ant. 1 jack, I detect 20 mV and with an RF probe, 2.7 Vrms. 
  Solder joints look good and parts placement seems to be correct. All 
diodes properly oriented.  T1’s leads show correct placement with clean 
solder on the wire above the board. With all power off, K17 shows 0 ohms 
from pins 1-3 and 1-4.  K2 in Tune mode at 20 watts on LCD was less than 30 
seconds and the dummy load showed no signs of noticeable warming.  Help with 
troubleshooting would be appreciated.

Tnx es 73.

Gil NN4CW