[Elecraft] 10 MHz external reference - GPSDO

[Joe Subich, W4TV]

 > 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
>>
>>
> ______________________________________________________________
> Elecraft mailing list Home:
> http://mailman.qth.net/mailman/listinfo/elecraft Help:
> http://mailman.qth.net/mmfaq.htm Post:
> mailto:Elecraft at mailman.qth.net
>
> This list hosted by: http://www.qsl.net Please help support this
> email list: http://www.qsl.net/donate.html Message delivered to
> lists at subich.com
>