[Elecraft] K2 CW filter "blow by" solution

[mark]

I have installed the KI6WX modification a week ago.=20
However, I still didn't like the fact that I could hear the signal of =
the strong station when I was listening to the week signal a few kHz =
away.
This probably wouldn't be as noticeable on a very crowded band. My house =
is on a hill and I'm using a large 4 el 20 to 10m and a 2el 40m quad =
antenna.
There are many signals S9 +20db and stronger on K2 or FT1000D S meter.

The experiment:

K2 CW version only, with W2 and W3 installed. (SSB option not installed)
Signal S9 +30db freq 28060.00 Mhz
Filter BW 400Hz  audible signal  from 28056.4 to 28064.0 Mhz almost 8kHz =
(that is not the filter response but rather the signal bypassing the =
filter).
With 700 or 100Hz BW is about the same.
The amplitude of the signal beyond the bandpass of the filter is audible =
but much lower in amplitude.

Next I installed a 1 inch copper tape.

With the tape:

Same set up as above:

Filter 700Hz audible signal from    28058.2 to 28060.0 MHz
Filter 400Hz - - - - - - - --- - - - -      28058.7 to 28060.0 MHz
Filter 100Hz  - - - - - - - - - - - -       28058.9 to 28060.0 MHz

NOT BAD 1.1 to 1.8 kHz BW depending on which filter is used.

Since I can't place the drawing of my installation, I will try to =
describe it;
Copper tape L=3D2.1" W 1"
Face the front of the K2
One corner of the tape is soldered to the top of X5 left side and the =
other corner to the top of X11, in the middle of the can.=20
The right front corner of the tape is cut L 0.65" W 0.5" so that the =
tape wouldn't cover the J10.
Also, left back corner is cut just enough so TP2 wouldn't be covered.
Solder only small area of the tape, 0.1" or so, to X5 and X11. Do not =
overheat X5 / X11.
I covered the top and bottom of the copper tape with kapton tape so it =
wouldn't short anything.=20

In my K2, this mod works very well. Now the cw filters work almost as =
well as the filters in the ft1000D.
Please try this and let me know how it works in your K2.

NOW THE BAD NEWS:
THIS MODIFICATION DOESN'T WORK IF SSB MODULE IS INSTALLED. THERE IS A =
"BLOW BY" PROBLEM ON CW AND SSB FILTER WHEN SIGNAL IS ROUTED THROUGH SSB =
MODULE.
IT'S A SHAME, BECAUSE I LIKE THE CW FILTERING AFTER MODIFICATION VERY =
MUCH.
THE ONLY HOPE IS THAT THERE ARE ENOUGH (CW ONLY) OPERATORS SO THAT THEY =
COULD ENJOY THIS IMPROVEMENT.

73! Mark WQ7X=20
=20



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