Eddy,
The K2 dial calibration does *not* depend on the 4 MHz reference
oscillator, except at the time CAL PLL and CAL FIL is done. The data
from CAL PLL and CAL FIL is stored in EEPROM and will not change unless
those routines are done again.
In other words, once CAL PLL and CAL FIL are finished, the 4 MHz
reference can drift all it wants to without altering the dial
calibration of the K2. Other than for the duration of CAL PLL and CAL
FIL, that 4 MHz oscillator only serves as a clock for the MCU and for
that purpose, it can have considerable drift without causing any problem.
How much is the dial calibration off? If it is less than 20 Hz, that is
the limit of the DAC used in the K2, and there is little that can be
done about that (unless you want to redesign it).
If you are experiencing drift of your K2, you might want to look at the
thermistor mod instructions for modifying the value of RA on the
thermistor board. If your K2 does not have the thermistor board
installed, then you should order E850138 and install it. If you do not
have the BFO L33 that has many turns and is secured by a high value 1/8
watt resistor, you should order and install the BFOMDKT.
If both of those are installed in your K2, you can change the
compensation for the PLL by modifying the value of RA on the thermistor
board. See the instructions on page 4 of
http://www.elecraft.com/manual/PLL%20upgrade%20rev%20C.pdf.
Take heed about giving your K2 sufficient time to warm up to temperature
before running CAL PLL and CAL FIL. The spec is for 5 minutes after
power on at 25 degC (which is 2 degrees higher than normal room
temperature).
73,
Don W3FPR
On 4/8/2014 6:49 PM, Eddy wrote:
With the expert help from Gary and Don, I believe I've finally gotten the K2
SSB audio to sound pretty damn good on both LSB and USB.
Thanks again Gary and Don for sticking with me, its been a frustrating journey!!
Next frustration, my particular K2 (Serial 3500+) the reference oscillator
doesn't seem to want to stay dead on frequency......the K2 it doesn't drift
while on the air, so much as every time I take the time to get it zeroed to WWV
a few weeks later it's usually off by several hundred cycles and stays there.
I've done this and CAL PLL a few times over the last 10 years, I guess ref osc
just doesn't like 4000kc
I built the K2 kit in 2001 and the rig has seen spotty usage until recently (I
retired) and gets daily use.
My K2 has the PLL mode as well as latest firmware updates.
Any suggestions? Or, is this as good as it gets with the K2?
73
ed
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