Re: 10Mhz Milliren Frequency References

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Greg Broburg
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Joined: Sat Apr 28, 2018 6:48 pm

Re: 10Mhz Milliren Frequency References

Post by Greg Broburg » Tue Apr 20, 2010 5:33 pm

I have some milliren 240 precision miniature ovenized 10 MHz references.

The units run warm because of the ovens dissipating 1W8 after warmup.

They have an input pin for fine trim -10V to +10V (much finer than

possible with the mechanical coarse tuning cap) Power supply is 11 to

28V, start up is 6W0. Aging rates for the standard parts is noted as 1

to 2 parts in 10E-7 per year for the basic part series, so under 200 Hz

drift at 1G0 Hz in a year. They have date codes of 1998 and were a

special version of the 240, series is 0545. Price is 75.00 includes 48

hour run, coarse calibration, and shipping. I cant go beyond a coarse

drift cal without building external circuitry to fine tune the trim

Voltage. You will need to do that yourself if you wish to get better

than the coarse trim value. These units are very small (1.5 in by 1.5 in

by .5 in tall) and dont have the maintenance problems of the rubidium

standards for the small penalty in drift. Best would be to build a DA

output that could store the cal value and convert to a filtered (low

tuning Voltage noise) between -10V to +10V. The tuning current is in the uA.


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