[Elecraft] WRONG SERIAL CABLE - FIXED for my K2

[Don Wilhelm]

Folks,
I just tried keying my DB9 connectors at the K2 end - SUCCESS - it will be
next to impossible to insert an incorrect cable on my K2 now.

I plugged pin 4 of the female DB9 that is mounted on the K2 with a short
piece of wire - I just searched through my pile of wires until I found one
that fit snuggly into the hole.  In my case, I used an insulated #22 wire
that had just the right insulation thickness to make it tight.  Whatever is
used should fit in with enough resistance so it will not fall out, even a
toothpick would do the job - one of the square cross section tapered ones -
try the small end first, and if it is not tight enough, break off about 1/4
inch and try again, eventually you will find a section of the toothpick that
will go in, but not come out easily.  The material is not important, it is
only important to mechanically plug the hole.

Removing pin 4 from the male DB9 requires a little more patience, but is not
too hard.  Grasp the pin with slender long nose pliers - be certain to grasp
it quite near the bottom, and then bend it back and forth and eventually it
will break off.  (I found bending across the connector was better than
trying to bend in line with the row of pins).  It took me all of a full
minute of bending before coming free - and I tried it on 2 connectors.  If
you bend the nearby pins a bit (I did on the first one) it is a simple
matter to bend it straight again with the long nose pliers and the tapering
of the hole on the mating female connector will tolerate a bit of
misalignment anyway.  Really slender tip pliers are a big help here because
the jaws must fit over just one pin and still allow some room for bending
that pin at its base.  One could use a bit of small brass tubing placed over
the pin rather than my pliers technique - anything capable of bending the
pin back and forth many times will do the job.

LOCATING PIN 4 -- look at the male DB9 with the pins pointing toward you and
the wide row at the top.  The wider row of  5 is numbered 1-5 going from
left to right, so pin 4 is the one next to last on the right end.  The
numbers are written on the plastic base material, and a strong light will
reveal them.

On the female connector, pin 4 is likewise on the wider row of 5 pins.  The
numbering will be mirror image from the male connector, so if the row of 5
is on top, pin 4 will be the next-to-leftmost pin.

Note to Tom Hammond - you have my permission to include this information in
your 'repair' document if you choose.

73,
Don W3FPR

----- Original Message -----

> Folks,
>
> The light just dawned for me - pin 4 of the DB9 connector is not used.
> Let's use that pin as a keying device.  Put a plug into pin 4 on the
chassis
> mounted female connector, and remove pin 4 from the male shell.
> It is not hard to implement and would prevent plugging a standard serial
> cable into the K2.
>
> Elecraft already has a part number for plugs that would work - one
(actually
> 2) is already supplied with the KPA100 for keying the connector on the
> Control Board - part number is E700065.  I can't locate my extra one right
> now to see if it fits, does anyone else have one who could test it for
> proper fit (tight enough so it will not come out)?
>
> Wayne and/or Eric, what is the possibility that a couple extra keying pins
> could be included with the KIO2 (and KPA100) and the manuals updated -
> likely with eratta pages?
>