OCXO/Si5351A Calibration/Testing...Wierd Failure!! #ocxo


Lee Hooper KG5VU
 

I assembled the OCXO kit a few weeks ago.  All seemed to go extremely well until I attempted to set the temperature of the crystal oven.  With the R21 potentiometer fully counterclockwise, the U3S functions as with the standard Si5351A module.  

When I advance the R21 to heat the crystal oven the power supply current begins to pulse rather dramatically at 1-2 second intervals.  The front panel display of the U3S generally goes blank or gives "startup" display. The frequency, monitored on my hf receiver, changes or sometimes the signal disappears completely (Probably the U3S is doing a restart).

I thought this might just be the power supply.  Tried an alternate power supply to no avail.  (I am powering the U3S thru Pin 2 and the heater transistors thru Pin 3 of the 11 pin connector at the bottom of the U3s board but both are connected to a common regulated power supply.). I have not tried using two completely separate power supplies... seems like this should not be necessary.

Has anyone encountered (and hopefully resolved) such a situation? 

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