The XO of type VFAC570 (U140) from Valpey Fisher has been substituted by
a 3.3V XO type CWX823 from Connor Winfield of freq 156.25MHz.

 A small Header PC has beeen developed based on a design from N2PK - Paul - with some minor modifications.
It fits nicely onto the pads for the original U140 where only one of the two +5V pads are used.
A complete documentation is found below by cliking on the links for Schematic and PCB layout, (both as pdf files and source files for the free Eagle PCB layout program from www.cadsoft.de , as well as Parts list, Gerber files and hints.

  The Schematic (pdf) -  The Layout (pdf) - The component placement (pdf) - The Eagle sourcefiles (zip)
  The Gerber files (zip) -The Part List - The the new libraries not part of Eagle library - A picture af the homemade PCB
Note the PCB is made of 1mm epoxy.  I have surplus of PCB's just mail me and I will provide a PCB at no cost in a letter until stock exhaust

Modification to the original schematic:

To ensure correct voltage (2.5V equal half supplyvoltage) to the input of U130 and U150 resistor R153 is removed and R151 changed to 12K.
The 4K7 resistor on the header PC is connected between the 3.3V regulator and R150 (2K2) and thus providing the above voltage of 2.5V.