[Elecraft] Strange behavior K2/ 100

[email protected] [email protected]
Sun Aug 18 22:28:00 2002


I wrote:

"RF getting into the voltage and current sensing circuits on the control
board is a known problem, particularly on 160 and 80 meters. There is a
recommended mod to either replace or parallel C42 (0.01mFd) on the
control board with a 0.1 mFd capacitor to alleviate this problem. . . "
==========
Geoff, K6TFZ wrote:

"I have in front of me my K2 Modifications for use with the KPA100 dated
June 12, 2002 Rev. A (applicable to all K2 Rev. A RF boards).  I do not
see the  modification which you describe above.

I also just checked the Elecraft website and was not able to find the
mods you describe above.

I would appreciate you directing me to the location where this known
problem is described."
==========
You won't find the mod on the Elecraft site.  The info about it was given
to me by Gary, who is the support for Elecraft, when I queried him about
the voltage and current fluctuations indicated on the K2 readout when
transmitting on 80m and 160m.  He said it was a common problem and
suggested the mod.

Elecraft apparently considers the problem significant enough that they
include a 0.1 mFd capacitor with the KPA100 kit to replace C42 on the
control board, evidently because higher power would amplify the problem. 
Page 20 of the KPA100 manual has a step which says, "Locate C42 on the K2
Control board, which is near the voltage selector switch, S1.  If the
present value of this capacitor is .01 uF ('103'), replace it with an 0.1
uF capacitor ('104').  NOTE: If you have an older Control board (rev XC)
that does not include C42, solder the 0.1 uF capacitor between pins 4 and
8 of U3 (LMC6842), on the Control board)."

73, de Earl, K6SE