Doug,
You are exactly right. If you follow the K2 history, you will find that
the K2 A TO B kit was issued to pull all the prior mods together as well
as providing instructions about the best sequence to use when doing a
full upgrade. That happened at the same time the B level boards were
laid out which incorporated all the prior mods (SN3000 and above).
So anyone contemplating a full K2 upgrade, start with the K2ATOBKT and
install the other kits when the A to B instructions call for them.
One other benefit is that the K2ATOBKT instructions tell you when to do
the alignment instead of doing the alignment after each of the mod kits.
The A to B mod will not quite get you to a post 3000 SN equivalent
unless you also change the IF crystals (not necessary if the SN being
upgraded is above 2560 which was when the crystals were changed).
That leaves only the K2 Keying Waveshape mod which appeared near SN
4600, but the kit has been discontinued for lack of a leaded PIN diode.
New K2 kits use an SMD diode on a carrier board, but so far, that SMD
diode has not made it into the mod kit instructions - yes, I know the
new KPA100 kit calls for it as a prerequisite.
It will also not deal with changes to the KSB2 (the PSK mod) and the
KSB2 crystals and bandwidth change to 2.4kHz. Check the resistors on
your KSB2 board against the mod instructions to determine if you already
have it installed, it was put into production early on.
Don't forget to upgrade the KPA100 too, the KPA100UPKT will 'do it all',
there is no need for the KPA100MDKT since the parts are included in the
KPA100UPKT.
So, there is the FULL story - I have upgraded many, many K2s. Anytime I
had an older K2 in for repair, I gave the owner the option of upgrading
or just repairing - almost all chose to upgrade. And my upgraded Field
Test K2 SN 0020 performs as well as a new one.
73,
Don W3FPR
On 10/28/2020 4:24 PM, Douglas Hagerman via Elecraft wrote:
For anyone considering updating an old K2, a small point that may not be
clear in the instructions is that the K2ATOBKT is sort of a "top level"
kit that "controls" the other mod kits. So instead of installing the
various kits in their calendar order of publishing (2001, 2002, 2003,
etc.), the way to do it is to get all the kits, then follow the
instructions for the K2ATOBKT. Those instructions call out the other
kits (e.g., "Now follow the instructions supplied with BFOMDKT") in the
appropriate sequence.
If you try to do them in calendar order (like I did), you will encounter
confusion regarding "missing" parts and a couple of cases of "didn't I
already change that???"
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