[time-nuts] HP5334B with 10544 OCXO

[Rick Karlquist]

Arthur Dent wrote:

>  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."

A mix of facts and folklore.  I would especially challenge the last
sentence.

Rick