Direct multiplication to 9192 MHz isn't used by any manufacturer of any atomic clock that I know of, due to its well known disadvantages. I can state for a fact that it was summarily rejected by the designers of the 5060/5061 (Cutler, et al). In the 5071, I (being the RF designer) also summarily rejected it. The architecture that is instead used is indeed complex and expensive as you say. It is also ACCURATE.
Rick On 6/1/2017 7:04 PM, Donald E. Pauly wrote:
https://www.febo.com/pipermail/time-nuts/2017-May/105566.html The lock system on the HP5071 is complex and expensive. My plan to improve the HP5061B is to to use a pair of third overtone crystals running at 91.9 mc and 100 mc. I have come up with the magic numbers to lock them together. This eliminates all multipliers with the exception of the A4 board. The 12.61 mc synthesizer input presently wastes half the microwave power produced by the 90 mc input in the unused lower sideband. Therefore only half the 91.9 mc drive is required. Eight bit ECL dividers in one package are available to perform the necessary lock. When multiplied by 100 to the cesium resonance line, the 91.9 mc frequency is a few cycles high so that C field currents are reasonable. With crystal cuts for zero temperature coefficient at 25°C, it is possible to get along without an oven. Room temperature performance at 25°C±5°C is ±15·10^-9. Oscillator warm up time would be measured in seconds. Square wave modulation of variable frequency and amplitude shows promise for reducing the noise effects of the beam tube. You can smoothly change the lock time constant, deviation and frequency. This would avoid the big disturbance of the HP5061B when you switch from OPR to LTC. (OPR=operate with 1 second time constant, LTC=operate with 100 second time constant) πθ°μΩω±√·Γλ WB0KV _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
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