[Elecraft] K2 #6425 low/no sensitivity - suggestions?

[TF3KX]

Hi - I am in the process of constructing my K2 and have two problems that may
or may not be related.

Problem 1:  Low, almost nonexistent RX sensitivity during Alignment II.  I
can manage to copy a carrier from my MFJ antenna analyzer and I have used
this to verify that IF and input circuits are peaked.  Injecting this signal
into the antenna terminal I can also verify that PRE and ATT work as
expected, as well as the crystal different filter bandwidths.  Using an IF
carrier from the MFJ I have poked a low level signal into various parts of
the IF chain.  An interesting thing is that I hear this signal much weaker
in the K2 audio when I touch it to the INPUT of IF-amp U12 (MC1350) than to
its OUTPUT.  In other words, that IF amp does not amplify, but rather
attenuate the injected signal.  I have re-checked all connections around
U12, re-flowed the solder, checked T7 and removed the overload diodes D40
and D41 - with no improvement.

Problem 2:  Low 8V regulator output, 7.56V.  As a result I could only adjust
the U2 pin 5 voltage to 3.60V using R1, in Alignment I.  Probing the
voltages derived from the 8V supply, they are of course 5-10% lower than
expected.  All DC voltages on U12 are consequently a little low, but
otherwise not abnormal.

I plan to get a local replacement for the 8V regulator, just in case.  But
does anyone have comments on the low sensitivity?  Would the low 8V level be
a possible cause for this?

73 - Kristinn, TF3KX
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