The FTS 4010 was designed to be a "portable" Cesium frequency standard and clock. True, it is battery operated, it has a handle on one side, rubber feet on the other, and even a 1970's style wooden enclosure complete with ventilation holes, but at 55 lbs I wouldn't want to carry it very far. If James Bond were to carry an atomic clock across the Berlin wall this would be it. It appears to have the same electronics as a FTS 4050 series frequency standard but also includes a time of day display and adjustable delay 1 PPS output.
The unit has an autolock on/off switch but I don't see a loop open/close switch. So I was unable to test it in open loop mode; i.e., measure the performance of the free-running internal quartz oscillator.
There is a Zeeman frequency input and a ten turn KnobPot for C-Field adjustment. The clock system includes a 1 PPS sync input as well as push buttons for 1 PPS sync enable, hours/minutes set, minutes/seconds set, and time hold. There is a 7-digit thumbwheel bank with a 1 second range and 100 ns resolution.
There are two DB9P connectors in the upper left along with a pair of red/green LEDs and a tiny 1/4 inch square analog meter showing red or white. I haven't trace the wiring yet so I don't know what these are for but my guess would be two additional inputs for DC backup power.
I don't have the manual on the FTS 4010.
And after all these years, S/N 101 still works. The following are performance plots.
| FTS 4010 after 1 hour of warm-up and Cesium lock acquired. This is a 2-day run. The Cs standard has the characteristic hump between 1 and 100 seconds, goes below 10-12 (1E-12) at 103 seconds, but doesn't get much below 7x10-13 (7E-13) even out to 105 seconds. |
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| Plots generated in my lab with TSCplot. See also Amateur's guide to Allan Deviation. |