[Elecraft] K2 drift Mod

[James Hammons]

     Drift is not a real operating problem, in the K2,  even for
digital modes using a computer software using SSB. Nor is the drift
unusual if compared to the specs of most transceivers.   My K2
measured about 1.2ppm per degree C drift for the PLL before removing
the extra crystal.  Thus for a 10 degree cold to warm up change at
14mhz it would drift 168hz.  This would only change the tone on CW or
SSB  the same amount.  Unless you were using a narrow filter less than
what we have found is recommended, eg .1 or .2khz,  would you loose
the signal.  Most likely you would just touch up the tuning before
this happened.  On digital modes AFC would follow the receive signal
or you could touch it up and you might not even be aware of it.   The
BFO drift is about the same but at 5Mhz it would be a fixed amount,
It will reduce or add to the PLL drift depending on whether the VFO
frequency is above or below the signal frequency.  So the BFO  is much
less of an influence on drift and will reduce overall drift, at some
frequencies.

    After removing one of the crystals in K2 #2748, the PLL drift was
reduced to less than .5 ppm per degree C.  This was an improvement to
less than half the drift before.    One of my crystals would pull 9.95
khz and the other 10.54 khz, which is the one I used.  I did the same
to the BFO to see what would happen and it didn't have near the range
needed. =20

    I am among those who like to tinker and improve,  Even though this
isn't strictly needed,  I also have much experience removing parts and
doing repair.  If you aren't this type I would wait until official
word comes out as what can be done.   I am going to wait for more
information before I do any further mods.  With the addition of the
KI6WX mod for drift PLL drift could be reduced to near zero. =20

    Most people will not have the equipment or interest to measure the
drift.  If you are among those,  I would wait before doing anything. =20

   =20