[Elecraft] high current with KXB3080

[Frederick Dwight]

Bruce,
    When I built and installed my KXB3080 modification I had high current on 80 meters...over 900 ma with a 12 volt supply.  However in my case I had high power on
80 meters...5 watts and around 4 watts on the other bands.  To troubleshoot this problem, I operated the kx1 out of the case for short transmit periods with about an 8 volt supply.  I had used a piece of insulation on the 2 close wires on the LPF board and verified that this was not my problem.  However whenever I pried the LPF board slightly away from the main board (1mm??) the 80 meter current dropped to a normal value and power on all bands was OK.  I never identified the problem, but apparently something was shorting with the LPF board snug against the main board.  With the LPF board pried slightly away there is no problem.  I do not think it is a cold solder joint since I can now tap the boards, wires, torroids, etc and nothing bad happens.  Perhaps when installing the LPF board against the main board a piece of tape or other insulation between the boards would prevent a short.  I now get between 3.0 watts and 4.1 watts on the 4 bands with my 13.7 volt supply (current about 600 ma)  and about 1.5 watts with an 8.2 volt supply.
  I also did the L3 modification and the power resistor modifications.  Possibly something is shorting on your LPF board.....or even the L3 modification.  For sure I would not test with full voltage, but with a fused power supply with something like 7 or 8 volts until you find the trouble.  
  PS...I had fun with my 5 watts on 80 meters for a few days until my conservative nature kicked in and I fixed the "problem".  No spectrum analyzer here, so who knows  what frequencie(s) my 5 watts was on !!!
                        Rick   KL7CW   Palmer Alaska   KX1 #  798