[Elecraft] K2 On the Way -- Planning for Mods?

[Ron D' Eau Claire]

> It's a bit hard to tell what's an "official" modification, what's a
> "recommending" modification and what's a special purpose or an
> experimental modification.
>
> >From my reading, about the only mod that appears to relevant to
> the plain
> K2 are changes to the crystal case grounding and bypassing to reduce
> filter blow-by.
>
> Is there something I missed? What other modifications are recommended out
> there?
>
> Bill Coleman, AA4LR, PP-ASEL

You touch on a point that has come up recently Bill: "official" vs.
"unofficial" mods.

IF we define as "official" mods those furnished by or personally recommended
that everyone make by Wayne or Eric at Elecraft, the only ones that I know
of  are the following:

"K2 2nd Stage Xfil Mod, for 'Flatter' SSB Filter Response" that fixes an
annoying tilt in the i-f output filter. This involves adding a transistor
switch that changes a capacitor value in SSB. It is only needed if/when you
want to listen to AM/SSB. According to a recent note from Wayne, this mod
will eventually be incorporated into the basic K2, but it must await the
next rework of the r-f board.

"K2 AF Pot Application Note" that fixes a problem with the audio gain
control that bothered many, but not all, users. The original design has the
audio gain control acting as a 'shunt' literally shorting out the audio at
the input to the audio amp. This worked well enough for most users, but many
of us noticed that we were always running the audio gain control down near
the minimum gain point. Also, our audio gain controls became very 'noisy'
with the level jumping around when the control was touched. Apparently this
was the result of the audio channels in some K2's having a lot more gain
than others. The fix re-wires the audio gain control so that it behaves more
like a normal 'audio taper' control and so it is no longer used right at the
minimum point. It greatly improves the 'feel' of the audio gain and
eliminated the 'noise' problem. I can't say that Elecraft has recommended
that those who are not bothered by the way their K2 audio gain works make
this change, but they HAVE recommended it to anyone finding the audio gain
control touchy or noisy.

Finally, there is a new mod from Wayne that is not on the Elecraft site yet
as far as I know. Some K2's exhibit a tendency to start QSY-ing at random
during a transmission. They would always increment upward in frequency as
the rig was keyed in CW (it might happen whenever the PTT is pushed in SSB
as well, but that would be a lot less apparent). The problem is that the
optical encoder is reporting tuning control knob movement during transmit
when in fact it has not been moved. It only happens if the encoder is
sitting right on the transition of an optical segment, so it happens rarely
and is almost impossible to do on purpose. The mod changes how the encoder
is used slightly, so this problem will not occur. Wayne posted it in an
e-mail to everyone, but I don't see it elsewhere yet.

Those are the ONLY "Official" mods that I know of. There may be others.
That's not to say that there aren't a LOT of GOOD mods out there that will
enhance your K2. But, you are right. It's darn near impossible to see which
ones Elecraft recommends be made and which ones they have not specifically
recommended. Those listed above are the only ones that I know of that Wayne
or Eric have specifically recommended.

Some mods, such as the grounding of the crystal cans at the bottom, have not
been recommended by Elecraft as far as I can see. I seem to recall that the
reason for not recommending it was that it is easy to ruin a crystal with a
tad too much heat when soldering at the bottom of the can.



Ron AC7AC
K2 # 1289