Author Topic: Are there dual mode SC-cut OCXO commercially available?  (Read 792 times)

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Offline notfaded1

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Are there dual mode SC-cut OCXO commercially available?
« on: January 08, 2020, 07:41:33 pm »
I've been reading about these dual mode OCXO where a low-noise dual-mode SC-cut oscillator simultaneously excites C and B modes in 3rd overtone resonator.  The research shows results demonstrating that the temperature frequency stability of the dual-mode OCXO is 60 times better than that of a free running OCXO.  Does anyone know if these are commercially available?  Attached is the full research about it from IEEE.  A block diagram of the method is also linked here:

https://www.researchgate.net/figure/Block-diagram-of-dual-mode-OCXO_fig2_267551968

I'm by no means an expert on these but the technique seems really good for an ultra-stable OCXO.  The compensated vs. free running OCXO difference in stability seems huge unless I'm missing something?  I was curious if you can buy these from someone since the research is from 2000?  Maybe no one here knows but I thought I'd ask since I know there are time-nuts here with orders of magnitude more knowledge than I have.

Bill
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notfaded1
 

Offline Leo Bodnar

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Re: Are there dual mode SC-cut OCXO commercially available?
« Reply #1 on: January 08, 2020, 11:06:52 pm »
I am surprised at their assertion
Quote
to prevent thermal deterioration of electronic parts, the oven temperature is generally kept at 70C, about ten degrees lower than the turnover temperature of SC-cut resonators.
It sets the tone for the whole research.
Would it not be better to get better components and more accurate temperature controller? I can imagine that if you stick a modern design - like IHR - in a double oven then you can achieve better stability than typical classic OCXO with less stress on the components.
Conceptually, this dual mode idea might work, but repeatability will probably be awful - I reckon frequency difference between the modes will vary wildly in a batch - with spurious modes in the way and all over the place.  This will probably make every oscillator into a unique hand-built part.
And in the end all it solves is temperature stability [of sub-optimal operation point] and does not address ageing, contamination, frequency jumps, pressure dependence, etc.
Leo
 
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