5071A lock-unlock normal-standby testing

Some experiments with a hp 5071A cesium frequency standard (std-perf tube, not high-perf tube).

5071 going from normal mode (locked to cesium) to standby mode (unlocked, free-running quartz)

When a 5071 goes from normal mode to standby mode there is an unexplained frequency jump, there is a significant reduction in short-term noise, and the frequency begins to drift.

Frequency: 2 hours locked (green), 2 hours unlocked (red)

Same, with zero offset

Note normal mode (cesium lock) has far more short-term noise but stays at constant average frequency. In standby mode (cesium unlock) the quartz short-term noise is very low but the frequency wanders.

Phase: 2 hours locked (green), 2 hours unlocked (red)

ADEV: 2 hours locked (green), 2 hours unlocked (red)

Same, compact scale