[Elecraft] Re: K3 Reference Oscillator

[wayne burdick]

Mike,

Maybe I wasn't clear on this. I said it was "accurate to 1 Hz ... at 
the calibration temperature." That says nothing about what happens as 
the temperature *changes*.

+/- 0.5 ppm (or +/- 1 PPM) is the most common high-stability reference 
option available for ham transceivers, K3 included. (And yes, this 
applies to the entire temperature range, not per degree C.)

The K3 has an advantage over most transceivers in this regard. The REF 
CAL menu entry can be used to enter frequency-vs.-temp data that's 
supplied with each individual 1 PPM oscillator. This data is used in 
conjunction with an accurate temperature sensor to fine-tune the 
reference in 0.2-Hz steps as the temperature changes. So we're actually 
expecting something like +/- 0.2 ppm over temperature. But we're 
specifying it conservatively.

73,
Wayne
N6KR



On Aug 29, 2007, at 9:29 AM, Mike S wrote:

> At 11:59 AM 8/29/2007, wayne burdick wrote...
>> 49.380 MHz. All signal sources are phase-locked to the refernce. Fine 
>> adjustment occurs in firmware, and once calibrated, it's accurate to 
>> about 1 Hz through 6 meters at the calibration temperature. The 
>> high-stability option is at the same frequency, with firmware 
>> correction to better than 0.5 ppm.
>
> 49,380,000 * 0.0000005 ppm = 24.69 Hz, and actually worse on 6 meters, 
> since it's a higher frequency. In any case, it's considerably worse 
> that the 1 Hz stated for the standard reference. Is that ppm/degree C, 
> over some temperature range, or ? Is the tempco specified for the 
> standard reference?
>
>

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