[Elecraft] K2 S/N #5396 up and running employing the Rework Eliminator & UNPCBs

[Joerg Tack]

Here's my report to share my experiences & ideas:

I've got my K2 up and running about 1.5 weeks ago after editing the manual
to incorporate the few points from the errata and the changes from the
Rework Eliminators Guide (www.unpcbs.com) to have a rework-free upgradable
K2.

It took me two weekend days and the evenings during the week in between to
get the bare K2 ready for the first QSOs.  ... Of course without finishing
the top cover installation with the speaker which came a few days later. ...

There havn't been any real problems on the way. All parts present - just
NE612 mixer ICs instead the NE602s mentioned in the parts list. I expected
them to be interchangable good products but went on the net for
verification. For an unexperienced builder this could be a bit confusing
since there is no mention of a potential substitute part in the parts list
or so.

- Rework Elimination -
Now that I've started assembling the add-on modules (K160M, KAF2, KSB2,
KNB2) I'm more than happy not to take the K2 apart again for rework related
to every module but plugging the modules in replacing the appendant UNPCBs.

All I can say: 
It's a great thing not requirering any disassembling when installing the
options now one at a time after finishing them!
Ken, Gary and whoever else was involved in getting these things out as a
little add-on value product did a great job. 
Mounting the additional header-sockets on the RF-board could - to my mind -
be performed a bit later in the assembly process than described in the
version of the Rework Eleminators Manual I had (to avoid touching them with
the soldering iron & for easier installation of some other bottom side
components). It looks like there are frequent updates of this document. A
newer version is already available on their WEB-site
(http://www.unpcbs.com/docs/pdfs/CompanionGuide.pdf) dated March, 5th.

- K160M option -
Installing the K160M option I disliked the idea of "hard-wired" soldering
the BNC socket to the module while having a "plug-and-play" method in all
other aspects.
My solution was to solder a single pin socket (derived from an old high
quality IC socket with the round pins) to the BNC center pin and ground lug
so the whole looks upwards. Then I slightly (!) solder-tinned one end of the
prepared connection wires which than plug just fine into the former IC
socket pins atached to the BNC socket. This way I could remove the K160M
completely from my K2 without heating up the soldering iron.

Also related to the 160 extension: I want to add a parallel capacitor to C14
(just soldered on the top side of the board attached to the pins of C14) to
optimize the BF tuning for 160m & 80m as both bands have common tuning
elements only and tuning L4 is pretty sharp. Currently I have to tune L4
about half a turn out on 160m when it was well set for 80m with significant
level differences.

- KAF2 option -
In the KAF2 bag there have been the four 0.22 uF capacitors missing which I
replaced by smaller valued ones I had in the junk box as an imterim solution
awaiting the small size 0.22 uF capacitors. Installation of this option was
as simple as unplugging the appropriate UNPCB, removing one screw, mounting
the standoff instead and plugging the KAF2 onto the Control-Board securing
it with the screw just removed.

The other KNB2 and KSB2 options are still awaiting their assembly ...


There are two things I'm wondering about after having the K2 ready:

* max. output power on 10 m is just about 12 watts and on 12 m 13 watts

* Setting the output power while in tune mode is a bit difficult 
  especially at around 5 watts since it "jumps" around partially 
  more than half a watt.
  
Is that normal, or has anyone an idea of what to do ?
If not I would start watching VPwr and the RF-level behind D36 to get a
feeling.


73, Joe
DF7TH

KX1#1029, K2#5396 

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