[Elecraft] K2 Internal ATU calibration issue

[Earl Richardet]

I've just completed the build on my internal K2 ATU.  I'm at the point of
performing the CALn Bridge Null Adjustment.  Following the procedures I am
unable to get any result other than "HI" unless I turn the power practically
down to zero.  Turning the power to zero I can get a reading close to 020.
However changing C55 doesn't lower or raise the indication.   I don't think
that the circuit is working as intended.  The voltage on pin 1 of U4 is
approx. 4.5 volts. With R6 removed.

 

I've looked over the components a number of times.  I've confirmed that all
the components in the circuit are the correct values, correctly soldered and
in the correct orientation.  Including L1.

 

Suggestions?