Posted by
Don Wilhelm-4 on
Sep 04, 2011; 9:07pm
URL: http://elecraft.85.s1.nabble.com/K2-power-on-frequency-problem-tp6756612p6759229.html
John,
You are reporting a shift of 128 Hz in one case, and 117 Hz in another
case. The difference between the two is close to 20 Hz which is the K2
BFO DAC limit, so that is not surprising, particularly if the BFO
voltage to the DAC is right on the "edge".
Yet, I do not understand what approximately 120 Hz has to do with CW or
CWr - unless you have the K2 sitting close to an AC transformer, sine
120 Hz is twice the 60 Hz line frequency and the shift is coming from
the VFO.
You may have some inconsistency in addressing the EEPROM. If that is
the case, it will be cured by a Master Reset - BUT record all your menu
settings before doing the reset and restore them afterwards. The K2 A
to B Instructions contain nice tables for recording the menu values, and
I encourage you to download those instructions to record the menu
parameters.
I would suggest you use the N6KR method to set the 4 MHz reference - the
precise setting may be slightly different than exactly 4 MHz, and the
N6KR method erases any variables other than your ability to tune WWV (or
any other "standard" station) with precision in SSB mode.
For the full K2 Dial Calibration procedure, see the article dealing with
that subject on my website www.w3fpr.com. If you only want to set the 4
MHz reference using the N6KR method and then run CAL PLL and CAL FIL,
you can refer to Wayne's document from the Elecraft reflector archives
of 8/20/03.
Remember, setting the 4 MHz Reference Oscillator by itself does nothing
to the dial calibration, one must run CAL PLL and CAL FIL to set the new
values (based on the new setting of the Reference) into EEPROM before
any chance in tuning is made.
73,
Don W3FPR
On 9/3/2011 9:24 AM, John Oppenheimer wrote:
> I am a new K2 (#7212) user. I have been baffled by what I thought was my
> inability to properly perform the frequency alignments. My last attempt
> was to perform a factory reset and re-do PLL and BFO (Table 8-1 values)
> calibrations.
>
> I believe that I have found the issue, sometimes it appears that the VFO
> frequency offset look-up tables are not used and a toggle through two
> "CW REV" changes are needed.
>
> Used a K3 CWT SPOT as a 4MHz monitor to adjust C22.
>
> Using a K3, CWT, SPOT and K2 in in TUNE (with dummy load) to measure the
> K2's frequency. Test process is:
>
> Note: only the events in the below text were performed.
>
> Power off K2 with F set to 7026.00
> Power on: K2 F=7026.00 K3 F = 7026.146
> "CW REV" "CW REV", K3 F = 7026.018
> Power off K2
> Power on K2 F=7026.00, K3 F = 7026.025
> Power off K2
> Power on K2, Move K2 F to 7027.00, K3 F = 2027.028
> Power off K2
> Power on K2 F = 7027.00, K3 F = 2027.145
> "CW REV" "CW REV", K3 F = 7027.000
>
> I was listening to the audio during the above process. There was a
> notable change in the resulting pass-band audio when the "CW REV" "CW
> REV" toggle was performed and the K2 frequency changed. Leading me to
> believe that the VFO offset frequency was changed.
>
> Though I can't find a reproducible process, I have found events where
> during a K2 power on session, sometimes a "CW REV" "CW REV" is needed to
> acquire correct K2 frequency.
>
> Is this normal K2 operation, or do I have an issue with this K2?
>
> John, KN5L
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