[Elecraft] K3 and a very high stability external reference oscillator

[Ian White GM3SEK]

Tom,  VK2OE wrote:
>I wonder if someone was trying to use a very high stability external 
>oscillator with the K3, for example a HP Z3801A. Or maybe another GPS 
>disciplined high accuracy oscillator.Another interesting field for 
>experimenting..... Tom, VK2OE
>

If you download the K3 Schematics file from the Elecraft website, the 
page for the KREF3 shows an 8-pin header (J4) ready for an "Ext Sync 
Module". This has connections for:
* 49.380MHz output from the existing XO module
* XO frequency control voltage
* External Reference input from the rear panel
* 5V
* 100Hz [1].

Draw your own conclusions. It seems that the Ext Sync module will 
contain a PLL chip to lock the existing XO to an external reference 
(most likely 10MHz).

The True Faithful will then be able to connect a GPS disciplined 
external reference, leaving no further doubt that the K3 was designed 
with a direct link to Heaven.


[1] The 100MHz bus wanders around various parts of the K3, terminating 
at the main controller. Has anyone worked out what it's used for?


-- 

73 from Ian GM3SEK
http://www.ifwtech.co.uk/g3sek