K2 3842 Calibration Blues

[William Moore-5]

Hi all,

This posting (appears below) may be recalled from last week.

Boy is my face red!

It turns out that Dan Barker, WG4S, was right. There was no problem with the
K2, just the builder. Thanks to Dan's reminder, I have finally realized the
K2 Calibration imperative "If the reference oscillator, is reset and CAL PLL
is run, it is imperative that CAL FIL also be run for all modes and all
filters used" Having followed this imperative, my dial calibration is now
within 20 Hz, using Spectrogram to align the filters.

I had thought that since the filters were previously set satisfactorily, I
shouldn't have to do it again after running CAL PLL. Wrong!! They do! As my
father told me "Son, there are occasions where it matters not what you
think, it matters only to do what you are told and this is such an
occasion." This certainly applies to me in this instance. Thanks to Dan,
WG4S and Stu, W6CUX for helping me finally understand the K2 calibration
imperative.

73,

Bill, VE2WMA



From: "William Moore" <[hidden email]>
Subject: [Elecraft] K2 3842 Calibration Blues
To: <[hidden email]>
Message-ID: <000701c67477$52694a00$0a02a8c0@dolmo>
Content-Type: text/plain; charset="us-ascii"

Hello all,

I am trying to fine tune the dial calibration and filters with Spectrogram.
I do believe that I have tied all the procedures available to accurately set
C22 to precisely align the 4000.00 reference oscillator. However, regardless
of method used and after running CAL PLL and CAL FIL, the dial readout is
250 Hz above what it should read on USB and 250 Hz below on CW normal but
spot on in CW reverse. Yes, I ensure that TP-1 is connected for running CAL
PLL and TP-2 for running CAL FIL. The CAL PLL linearization process seems to
proceed normally.

All PLL, VCO and BFO tests are perfectly within range; R 30 reads a healthy
6.07 volts, CAL FIL has been perfectly set (in CW only) with Spectrogram.
The radio performs perfectly in all other respects. I should point out that
K2 3842 is currently just a basic K2, no add on accessories as yet.

For reference frequencies using the W3FPR method, I used CHU on 3330 MHz and
7335 MHz (both are USB transmissions with carrier reinserted), W1AW on
7047.75 CW normal and WWV 10000.00. Given current band conditions, WWV is
pretty weak way up here in north-eastern Quebec and I don't always get a
very good reference for Spectrogram. For most all of my alignment attempts,
I  used a combination of the W3FPR method for us tone challenged persons and
then the N6KR system to mathematically set C22 using the frequency readings
at TP-1 and TP-2.

So, I am stuck. I can only conclude that the DAC is either adding or
subtracting 250 Hz to dial read out. But hey, what do I know? My background
is economics and the rules of supply and demand don't apply to this case.
Can anybody shed some light on what I am doing wrong in the alignment
process so I can resolve my calibration blues.

Thank you and 73

Bill, VE2WMA


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