[Elecraft] Adjusting 4Mhz in K2

[Masleid, Michael A.]

Hi Tom,

First things first on calibration:  If it works well enough, use it!

I guess I'm a piano tuner at heart.  I wanted to see just exactly how
far things are from being exactly right.  Let me apologize up front.
The following is nit picking.  In reality, something that is not
exactly right in not exactly wrong either.

On to the nit picking:

>I thought I would share my way of adjusting the 4Mhz osc. in K2 3829. =
Since=20
>I did not have a good freq.counter I decided to use my ic706 for this.

The frequency stability specs for the standard ICOM 706 MKIIG are =
similar
to the K2's.  To really push the K2 to the limit, you'll need to know
how far off frequency the ICOM 706 is.=20

>The manual tells to use USB on 4,000Mhz and adjust the trimmer to zero
>when no pitch is audible.  I made a pickup loop ...
>I then put vfo A to 3999,80Khz USB and vfo B to 4000,20Khz LSB ...
>Adjusted the trimmer C22 so the pitch in tone sounded the same ...

This is one way to set the C22 to exactly 4 MHz.  I believe that you
will get better results if you set C22 to exactly 3,999,986.7 Hz.
At least, that is what worked on #3430 and some others.  It had to
do with how CAL FCTR (and PLL) works I think.  You then have to run
CAL PLL and do the steps in CAL FIL of course.

>Then I did a test with both radios on same frequency(7084,00) and
>transmitted first LSB and then USB and my K2 was right on with
>no difference in voicepitch from my normal voice.

If the ICOM 706 was not perfectly calibrated, and you used it to =
calibrate
the K2, the K2 would be calibrated to the same error, so they will seem =
to
be exactly correct to each other...

But what I believe is a 13.3 Hz error at 4 MHz due to setting C22 to
exactly 4 MHz would cause a 18 Hz error at 7 MHz.  You should have heard
that...

>To me this sounds good enough. What do you think.

I think you right.

>if they should not use this method I would be glad to hear why.

Check it out on 10 meters.  If there was any error, it will be worse at =
higher
frequencies.  If it is all still good, you have a winner!

Don, W3FPR has a collection of good methods at his web site:
www.qsl.net/w3fpr

73, de Michael, AB9GV