[Elecraft] K2 w/KSB CW reverse BFO

[Don Brown]

Hi

This procedure for setting the 4.000 MHz clock is right out of the Elecra=
ft manual page 98 and it does put the 4.000 MHz clock on frequency calibr=
ated to WWV. This is a better way to do it because placing a probe on the=
 4.000 MHz test point will detune it a little. Even if you have a frequen=
cy counter and you adjust the clock by measuring the reference oscillator=
 per the manual on page 57 it will not be as accurate as the calibration =
to WWV on page 98. My procedure is just a slight modification of this met=
hod. I have done 8 or 10 K2's this way and it works better than the simpl=
er methods in the cal setup on page 57.

Don Brown
KD5NDB
----- Original Message -----
From: k6se@juno.com
Sent: Thursday, October 31, 2002 4:05 PM
To: DolfinDon@msn.com; vr2bg@harts.org.hk; elecraft@mailman.qth.net
Subject: Re: [Elecraft] K2 w/KSB CW reverse BFO

KD5NDB wrote:

"The first thing is to make sure the K2 is on frequency you can check
that by looking at WWV with Spectrogram looking for the 500 and 600 Hz
tones on alternating minutes (you may need to wait a little, the tones
are not on all minutes of the hour). Use USB or LSB mode. Set up a marker
at 500 and 600 Hertz on the Spectrogram display. When you have the tones
on the spectrogram markers, read the VFO frequency and write it down.
Connect the frequency probe to TP3 in  FCNTR mode and adjust C22 on the
control board to change the indicated frequency by the amount needed to
make the VFO correct."
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
Although you can make the VFO frequency readout accurate (ignoring the
K2's temperature drift problem), I was told by Elecraft that if C22 on
the control board is not adjusted so that the 4.000 MHz oscillator is
exactly 4.000000 MHz that the K2's built-in frequency counter will not be
accurate, and that it should be adjusted that way and we should accept
any VFO frequency readout error which might occur as a result.  With the
4.000 MHz oscillator adjusted properly, the BFO frequency readouts will
be accurate when setting up the filters (as well as any other frequency
measurements done with the built-in frequency counter).

In fact, the #1 choice of setting C22 in the K2 manual is to set if for
exactly 4000.0000 kHz [and ignore any VFO frequency error].

73, de Earl, K6SE


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