[Elecraft] KNB2 does not work on my power line noise

[Roger Marrotte]

I have a KNB2 for my K2.  The PC board says 1999 ELECRAFT REV D.  The
microcontroller says NB102.  I sometimes have power line noise at about =
an
S5 level, usually between storms.  After a storm the noise goes away for =
a
few days to a week.  The noise blanker has absolutely no effect on the
noise.  It doesn't matter if I use NB1, NB2 or LO THR.  It's as if the
blanker was still off.  I recently built a K2 for a friend and this past
week he raved about how the noise blanker on his K2 completely removed =
his
power line noise (also about an S5).  He lives about 15 miles away so =
it's
not the same noise. I haven't bothered with my noise blanker for a long =
time
since it does nothing.  Yesterday, remembering my friends rave report, I
looked into my noise blanker problem again.  It still did nothing for =
the
noise.  I found a suggestion on the reflector that recommended changing =
C11
from 0.001uF to 0.0068uF and C12 from 0.0068uF to 0.047uF.  I made the
changes and still no noise reduction at all.  I then took my K2 over to =
my
friends house.  He turned on his K2 and let me hear his power line =
noise.
It sounded just like mine.  He turned on his noise blanker and the noise =
was
gone.  I then connected my K2 to his antenna turned on my noise blanker =
and
the noise was gone!  I guess my noise is different enough for the noise
blanker not to work on it.  Does anyone have any suggestions for me.

Roger, W1EM