John,
The specified stability for the K2 is less than a 100 Hz drift from a
cold start at 25 degC, so your K2 is within the specification (granted
it is just on the border). The drift will usually be worse for a K2
with the KPA100 installed than a basic K2 because there is more heat
generated in the enclosure and less air volume present to disperse it in..
That is a 'cure' --
Is the serial number of your K2 less than 3446?
That is when the PLL Temperature Stability change (Thermistor Mod)
became available.
If you have a K2 below SN 3000 that has been upgraded, than that mod was
likely installed with the upgrade.
Examine the K2 RF board toward the left side near the front - if there
is a small board sitting vertically in the RP3 location, the mod has
been installed. You may have to remove the KDSP2 option to see it.
If your K2 does not have it, a kit to install that thermistor mod is
available from Elecraft - PN E850138.
If you do have that mod installed, the installation instructions for
that mod have guidelines for advanced builders about altering the value
of RA to achieve better drift compensation for your K2. You can
download those instructions from
http://www.elecraft.com/manual/PLL%20upgrade%20rev%20C.pdf.
Note that the information about altering the RA value does not appear in
the K2 manual, and is intended only for those advanced builders who have
good capability for properly measuring the drift that results after
changing RA. It may take some experimenting to find the right value for
your K2..
73,
Don W3FPR
On 7/24/2013 11:59 AM, John Oppenheimer wrote:
My K2 has a 100 Hz difference in CAL FIL frequencies between cold and
full warm up. The 100 Hz difference renders the 200 Hz BW unusable until
the K2 warms up.
Is this typical, or do I have a component with excessive temperature
instability?
John KN5L
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