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OCXO/Si5351A Synth kit

Mike Berg
 

Just built up the oven controlled synthesizer and was wondering what the final recommendations were for the oven controller mods to prevent runaway?

I'm running some PIC assembly code from AA0ZZ and the synth checks out hardware wise and I want to avoid any issues others may have had before I finish soldering the case shut.

73
Mike  N0QBH

Mike Berg
 

Did some experimenting with the stock configuration and found it unacceptable due to high I and it seemed to "hang" at 300 mA.
I ended up going simple and reversible with a 0603 SM 22k resistor parallel to 56k R5.



Very satisfied with performance now. Max I after cold power up at about 240 mA then settling down to about 100 mA heater I at 40C.



Test jig with a PIC 16F628A @ 4MHz running some assembly code written for the Si5351A.

 

73
Mike N0QBH