[time-nuts] HP5334B with 10544 OCXO

Arthur Dent golgarfrincham at yahoo.com
Mon Jan 30 16:36:34 EST 2012

> Other than taking longer to warm up does anybody see any problems with
> this?  Basic testing shows the unit seems to work OK.  It is reading 1.7
> Hz low compared to my Thunderbolt at 10 MHz - I have not tried adjusting
> the trimmer on the 10544 yet.
> Comments and thoughts appreciated.
> Regards.
> Mark.

 At http://home.teleport.com/~oldaker/10mhz_construction.htm which has TAPR info, 
I found this description of the differences. If you have a Thunderbolt or rubidium to feed 
in to replace the internal oscillator, or you're not concerned about leaving the oven 
energized 24/7, it probably doesn't make much difference as Rick Karlquist said.

"The HP 10811A/B, using an SC-cut resonator, is very similar physically to the 
HP 10544 that used a AT-cut resonator.  The SC-cut crystal has several advantages 
compared to the AT cut.  It has a much smaller temperature coefficient,  the resonator 
can be operated at a higher drive level, which improves the signal-to-noise ratio and 
short-term frequency stability without degrading the aging rate;   it has faster warm up 
with less frequency overshoot. The SC cut is a doubly rotated resonator and requires 
much tighter angular tolerances when the crystal is cut from the quartz bar. The SC-cut 
resonator came into commercial production around 1980.  The use of SC-cut resonators 
in oscillators immediately improved their performance of the stand alone HP 10811 
series OCXO installed in their test equipment.  In our use we are able to improve on the 
HP frequency stability specs by a factor of 100 to 1000 depending on conditions."

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