[Elecraft] 10 MHz external reference - GPSDO

[David Anderson]

I am not arguing about that calculation Joe, it's proof that you don't need GPSDO accuracy as if will be several orders of magnitude better than that. 

73 from David GM4JJJ

> On 11 Mar 2016, at 18:25, Joe Subich, W4TV <lists at subich.com> wrote:
> 
> 
> > While locked to the external source, the K3’s reference
> > oscillator frequency is maintained within 2 Hz.
> 
> The K3's reference oscillator is 49.380 MHz (+/-) not 10 MHz.
> 
> The K3EXTREF uses the external 10 MHz signal to gate a counter
> which counts the reference.  That count is then used to adjust
> the reference frequency.  Maintaining the 49.380 MHz reference
> +/- 2Hz is on the order
> of 0.04 ppm.
> 
> 73,
> 
>  ... Joe, W4TV
> 
> 
>> On 3/11/2016 1:07 PM, David Anderson wrote:
>> Dick,
>> 
>> I found the reference to that figure I quoted, it is in the K3EXREF
>> manual:
>> 
>> The K3EXREF option locks the K3's reference oscillator frequency to
>> an external 10 MHz source by automatically controlling the REF CAL
>> function. While locked to the external source, the K3’s reference
>> oscillator frequency is maintained within 2 Hz. Since the K3EXREF
>> does not phase lock the K3’s reference oscillator, the external 10
>> MHz source has no impact on the K3’s phase noise performance. For
>> best performance we recommend your K3 be equipped with the KTCXO3-1
>> high stability (0.5 ppm typ.) reference oscillator.
>> 
>> 
>> 73 from David GM4JJJ
>> 
>>> On 11 Mar 2016, at 16:55, Richard W. Solomon <w1ksz at earthlink.net>
>>> wrote:
>>> 
>>> I am a tad confused over this issue. Perhaps I need to read up on
>>> how Elecraft controls frequency.
>>> 
>>> My understanding on a "Locked" frequency would infer that the
>>> result would be a LOT closer than 2 Hz @ 10 MHz.
>>> 
>>> Is there a detailed description of the process somewhere that I
>>> could read ?
>>> 
>>> 73, Dick, W1KSZ
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