[Elecraft] Volunteers to Test K2 Stability Mod

[John, KI6WX]

For the the last month I have been looking at mods to the K2 to reduce the
frequency drift with temperature.  The experiments have been quite
successful and I have been able to reduce the drift of my K2's VFO by a
substantial amount.  I believe this change can be applied across the general
population of K2's, but first I need to get some volunteers to test the mod
on their own K2.

The purpose of this experiment is to prove that this type of change can be
applied across a number of K2 transceivers and reduce the frequency drift in
all of them.  The change requires adding 4 resistors and a Radio Shack
thermistor (#271-110) to the backside of the K2's RF Board.  The thermistor
and resistor network vary the bias to the varactor diode over temperature to
cancel out the frequency drift.  There are no cuts required on the RF board
to implement this change, and it can easily be removed by unsoldering the
resistors and thermistor.

Your will need to meet the following requirements to participate in this
test.

- The Elecraft PLL and BFO Temperature Stability modification (Elecraft
#BFOMDKT) must be installed in your K2.

-  You must have some means to determine the K2's drift before and after
making these changes (frequency counter, WWV zero beat, etc.).  This
includes some method to vary the K2's internal temperature such as
alternatively transmitting and receiving with a K2/100 to increase the
internal temperature of the K2.

- You must be willing to take the time to send me a report on the results of
your experiments.

- This change is not suggested for a beginning kit builder.

If you are interested in participating in this experiment, please send an
email directly to me.  I will send you an instruction sheet on how to
implement the change.

This modification has not been tested or approved by Elecraft.  Any
modification approved by Elecraft will be slightly different than the one I
have done and will use a different thermistor.  DO NOT CONTACT ELECRAFT
ABOUT THIS MOD.  They are aware of my experiments on the PLL reference
oscillator, but they do not know the details of the mod.  If you have any
questions, contact me directly.

-John
 KI6WX
 ki6wx@pacbell.net