[Elecraft] Another K2 Design Deficiency

[k6se@juno.com]

While I'm on the subject, here's another K2 design deficiency that can be
easily corrected:

K2s without the KPA100 have a 0.01 mFd bypass capacitor at C42 on the
control board.  This capacitor adequately bypasses any RF present on
frequencies at 40 meter and higher, but not on 80 or 160 meters.

The KPA100 kit includes a 0.1 mFd capacitor to replace C42 on the control
board, presumably because the problem with inadequate bypassing at C42
would be more severe when running higher power.

You K2 owners without the KPA100 can do this simple test to see what I
mean:

Go to the 80 or 160-meter band (and dummy load) and tap DISPLAY until the
voltage and current readings are displayed.  Set the POWER control for 5
to 10 watts output.  Then press and hold TUNE and observe the current
reading.  Most likely, you'll see it fluctuating wildly.  The fluctuating
reading is due to RF getting into the current sense circuit on the
control board.

If Elecraft provided a 0.1 mFd capacitor rather than a 0.01 mFd capacitor
for C42 in the K2 kits (along with an item on the addendum sheet), then
the fluctuating current problem would not exist on the K2 and there would
be no need for KPA100 builders to desolder C42 and replace it.

You won't find this mod mentioned anywhere on the Elecraft web site.

73, de Earl, K6SE