http://elecraft.85.s1.nabble.com/Need-help-for-sick-K1-tp389102p389113.html
Thanks for posting this Tom. It has since been written as an application
markers. It is easy to get within 10 Hz this way.
SPOT tone. Of course, if you zero with the 500 Hz tone thinking it was the
> -----Original Message-----
>
> Here's an 'improved' method for zeroing the MCU master Oscillator.
> Comes directly from the designer, N6KR:
>
> Subject: 4 MHz oscillator cal method for the K2
> Date: Wed, 20 Aug 2003 13:57:44 -0700
> From: Wayne Burdick <
[hidden email]>
>
> All of the methods that have been described for
> calibrating the K2's 4-MHz oscillator will work. But I use
> a different technique that allows C22 on the Control board
> to be set to precisely to the correct position, with no
> guesswork.
>
> This method relies on the following simple observation. If
> you tune in an on-air signal at a known frequency, the
> difference between the *measured* VCO and BFO (using CAL
> FCTR) *must* equal that frequency, or C22 is not set
> correctly. (Actually, this holds for 160-17 m; on 15-10 m
> it's the sum, or VCO + BFO, that must equal the signal's
> frequency. But it's easier to do the adjustment of C22 on
> 17 m or lower because you don't have to do any math at
> all, as I'll explain below.)
>
> Here's the procedure. It requires revision 2.XX firmware,
> and assumes you have already done Alignment and Test, Part
> II, at some point. The K2 should also be allowed to come
> up to room temperature.
>
> 1. Tune in a signal at a known frequency. Use one that's
> at an *exact* kHz boundary, so you can easily see when
> the VCO and BFO readings match in step 2. (I use WWV at
> 10, 15, or 20 MHz.) Use USB or LSB mode rather than CW,
> so that there will be no CW receive offset. In the case
> of a K2 I was calibrating, the VFO read 10000.17 when
> the signal was tuned in perfectly. If it had read
> 10000.00, no further improvement would have been
> possible.
>
> TIP: Zero-beat the carrier precisely, or listen to a
> voice signal and adjust the VFO for the best quality.
> The more accurately you tune in the signal, the more
> accurately you'll be able to set C22, below.
>
> 2. Run CAL FCTR. Now alternately move the K2's internal
> counter probe between TP1 (VCO) and TP2 (BFO),
> adjusting C22 in small increments until the kHz and Hz
> digits at the two test points match as closely as
> possible. In my case, the two readings matched at
> 14913.60 and 4913.60. The difference is exactly
> 10000.00--the frequency of the on-air signal.
>
> 3. Put the counter probe on TP1 (VCO), switch to 40
> meters, and run CAL PLL.
>
> 4. Put the probe on TP2 (BFO) and run CAL FIL. For each
> operating mode, vary each filter (or BFO) setting up 1
> count, then back down, to force the K2 to take a new
> BFO measurement for each and store it in EEPROM.
>
> The VFO dial should now be very well calibrated.
>
> If we get a lot of positive feedback on this method, we'll
> post it as an application note.
>
> 73,
> Wayne
> N6KR
>
> You might want to hold up on dong anything at this juncture, until
> you get everything assembled and tested. It won't HURT to perform it
> now, but you might need to re-do it at the end as wel..
>
> 73,
>
> Tom Hammond N0SS
>
>
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