[Elecraft] KAT2 problem: bridge null adjustment

[Stephan Walder, HB9DDO - K2]

Hello all

problem solved, thanks for all the supporting remarks that came back. It's
great to have so many helpful friends out there around the world...

If you're interested to know what was wrong, please read on...

If you're interested to learn about some of the lessons I learned, please
read on...

Please don't read on, I feel like a complete idiot and just hope none of the
guys I work with read this, my reputation will be gone...

What went wrong:

actually two things were wrong as I learned tonight first reading all your
comments and then going calmly over the troubleshooting section again:
actually the second last sentence in the troubleshooting section that
applies to my problem (can't get a reading of 010 or lower in CALn) reads as
follows: "Make sure you dont have the center conductor and the shield
exchanged at J7." Guess what ? They were exchanged. Ok, that was the first
time I felt a little foolish after annoying the email-list with something
that was well described in the manual; at the same time I thought: well you
can easily fix that little stupid... So I did, assembled everything again,
run thru the test agian and guess what ? Same behaviour.
Ok, what's next ? Read over your email comments and thru the manual again or
just put the project aside for tonight and get a good book ? This thought
lasted for about 7 seconds then I took the assembly apart again (hey, the
drill did me good, I'm real fast by now with this part ;-) and started to
check all the solder joints on the relays, T's etc. And than it sprang right
in my eye: to much solder causing a connection between pins 7&8 on P5 and
and L5 - obviusly this doesn't help a lot trying to get RF out of the thing.
The rest is well known history to all of you who completed the KAT2: the
needle on the RF-meter came alive immediatly, some playing around with C55
(finally getting it down to 009) and so on...
The ATU seems to work nicely, managed to get the SWR down to 1.3 or better
on all bands from 80 to 10 on my short G5RV - remains to be seen how good
the antenna actually works in my location.

Lessons learned:

ok, now for the other part of the story. For how many times did I read the
discussion about taking your time when building the kit, actually enjoying
this part etc... And I ignored it...

1) working too long on the K2, deep into the night, after a hard days work
rellay doesn't help
2) trying to keep the kids busy with the Internet on a late sunday afternoon
after we all spent a couple of hours out in the snow and sun and then trying
to assemble something easy like J7 is definitely NOT a good idea

Two lessons learned ain't enough ? Well first of all I'll try to remember
the when starting with the next option kit ;-)

Now I'll turn over the bands once more and then I'll read a book. The fun
will be next weekend: there's to hand out a few points in the CQ DX 160m and
hopefully collect a few new ones on the top band (that'll be QRO, the 160RX
option is not built yet), then there's a friend of mine who'll see and touch
the K2 for the first time (but who heard me talking about nothing elseever
since I ordered it in mid-december and last but not least I hope I can catch
N4BQW/KH9 for my DXCC #311 :-)

Ok dear fellow hams, thanks again for your support and I look forward to
meet you on the bands ! 73, Stephan, HB9DDO, K2 S/N 3128