[Elecraft] [K2] CAL FIL Temperature Sensitivity Question

[Don Wilhelm]

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
>