[time-nuts] Part 2: Atomic Clocks: It is important that they keep good time.

[Tom Van Baak]

> What are the units on the lower right with pairs of analog meters?

Hal,

Those are all 24 VDC backup power supplies. Model hp 5085A. The round meters are for volts and amps.

Take a look through http://hpmemoryproject.org/an/pdf/an_52.pdf which is an nice old (1965) copy the classic hp AN52 app note on Frequency and Time standards. The 115 clock, 5060 cesium and 5085 battery are on the front cover.

Highly recommended -- scroll down to PDF page 85. The 6-page Appendix VI is a wonderful summary of all the vintage equipment involved with precise time in the 60's. From the 5060A cesium standard to the 5085A power supply to the 115BR divider / clocks. It was my eBay shopping list many years ago.

Steve Allen -- you'll enjoy pages 83-84 for the historical notes on time scales, including NBS-SA, "stepped atomic time".

Note there were several versions of the DC backup power supply. The K02-5060A version is seen here:

http://hpmemoryproject.org/news/flying_clock/celebration_01.htm
http://hpmemoryproject.org/pict/news/flying_clock/flying_clock_rack_1200px.jpg  (high-res)

More examples of "flying clocks", showing the pairing of cesium clock(s) with battery backup along with dividers / clocks / counters:

http://www.lightandmatter.com/article/hafele_keating.html

/tvb