[time-nuts] Is this DOCXO an SC or AT cut rock?

Scott Newell newell+timenuts at n5tnl.com
Sun Aug 10 02:54:46 EDT 2014


I'm curious if an OCXO has an SC or AT cut crystal in it. There's no 
EFC, so I can't measure sensitivity. I did measure the frequency 
change from cold startup, thinking that an SC cut would stabilize 
quicker than an AT. I don't have a good AT OCXO to compare against, 
but I do have a Morion MV89A (should be an SC, right?).

Graphs:
http://n5tnl.com/time/mv89a/mv89a.png

http://n5tnl.com/time/mv89a/unknown.png

Thoughts?

The two units are the same size and shape. The Morion ran without the 
outer can.


Measurement note: my 5370A is sick, and my 5345A doesn't do GPIB. So 
I shot video with the counter (1 s gate time, using a tbolt as the 10 
MHz ref) and meter (measuring current) in the frame. From there, I 
used vlc to spit out still images at about 1 Hz, then imagemagick to 
cut out the sections with the seven segment displays. ssocr 
(<http://www.unix-ag.uni-kl.de/~auerswal/ssocr/>) did the real magic 
of converting the seven segment displays in the images to text. Had 
to do some hand cleanup on a few data points, but it was a lot less 
frustrating than typing in thousands of data points by hand. I'm sure 
it'd work better with a more careful layout and lighting.


-- 
newell N5TNL




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