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

Lee Hooper KG5VU

Based on your initial comments, I set the power supply to the U3S at 5.25V and then used a separate metered power supply for the heater transistors.  This eliminated the problem on the U3S doing repeated resets!!! I was also able to observe the reason for the resets as the current to the heater circuits was extremely high at times.

I played around with this for several hours. At times it appeared to be working correctly, but when I turned of the heater circuit allowing the crystal oven to cool.... then it would either not start to heat again or else it would exhibit the extremely high current phenomena again. 

I have not try restarting the U3S as opposed to just restarting the heater circuits; I can see from your comments that this could be critical.  I am also thinking of reducing the voltage to the heater circuit perhaps by using one or more 1N4001 diodes in series to drop the input voltage.

Can't thank you enough for your time and suggestions!!

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