[Elecraft] K2 alignment after removing X2 (Logic Check?)

[Don Brown]

Hi

You can cut the VFO drift with temperature in half by simply removing one=
 of the reference oscillator crystals. I remove X2 then check the referen=
ce oscillator range as described on page 57 of the manual. If the range i=
s at least 10 KHz then you can use that crystal by itself. If it does not=
 have enough range try the other crystal. Most of the newer crystals will=
 have just a little over the required range and are fine but you may need=
 to order a new set if yours won't make it. This also makes the VFO calib=
rate more accurate because the 12 bit DAC's 4096 counts are spread out ov=
er 10 KHz rather than 12-15 KHz. This makes each step a finer adjustment =
of the range between the steps of the PLL chip. This allows the CAL PLL r=
outine to calibrate the dial more accurately. =20

If you remove the crystal then you must make sure the 4.000 MHz clock is =
accurate and then run CAL PLL. The only time the 4.000 MHz clock needs to=
 be accurate is while CAL PLL is running or when you are setting up your =
filters. It is not used at any other time except as a clock for the MPU. =
Just follow the instructions in the manual on page 57 and/or 98 to get th=
e clock on frequency and run CAL PLL on 40 meters (assuming you have 2.XX=
 firmware). I prefer the page 98 method as it is more accurate because it=
 uses WWV as the standard. There has been some discussion about which is =
the better method lately but after re-reading the procedures on page 57 a=
nd 98 and performing both methods on 7+ K2's, either will put the K2 on f=
requency within the stated specification. That is assuming the counter is=
 accurate. I don't think I need to worry about WWV's accuracy ;-) =20

Don Brown
KD5NDB

----- Original Message -----
From: David A. Belsley
Sent: Sunday, November 03, 2002 8:10 AM
To: Don Brown
Subject: Re: [Elecraft] K2 alignment after removing X2 (Logic Check?)

Don:
  I've been a way for a month and a half and missed the issue behind this=
 =20
thread.  Could you kindly fill me in?

many thanks,


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