[Elecraft] K3S XREF GPSDO recommendation needed

[Mike Harris]

I don't think that is correct. Nothing touches the TCXO, the VCTRL pin 
is not used. The EXREF module just reads the actual ref frequency and 
that information is used to set up the synths. As the TCXO drifts the 
synths just use the new measured ref frequency.

Regards,

Mike VP8NO

 > BTW the K3 frequency is established by the TCXO and the external
 > reference merely performs a periodic check. Any freq error causes a
 > correction instruction to the TCXO to bring it back onto frequency.  The
 > TCXO-3 is rated at 0.5 ppm which is +/-5 E-7.  Adding the EXREF limits
 > drift to 0.1ppm or E-7.