Okay, just have to share. I had been waiting for an HP 419A for years, finally found one last year and totally rebuilt it (after trying to blow it up). See here;
https://www.eevblog.com/forum/other-blog-specific/great-meter!-the-hp-419a-dc-null-voltmeter-(restoration)/msg3565331/#msg3565331Someone posted a photo of a Weston Standard cell, which lead me down the road to wanting to find one, just to play with or set on my shelf with other old odds and ends. I found one, then started reading all the old NBS bulletins and became fascinated. The first sample I got was an old square Leeds and Northrup box that still measures 1.01747 so the cell is no longer good or stable, but makes a nice show piece on the shelf. Just out of fun, I decided to pickup another I found for cheep, which then lead to a third before the second even arrived.
The new boxed both arrived on the same day, but I was headed out of town, so they sat in my shop for a few days before I could play with them. Got home today and measured them for the first time using the DMM7510 at 10G
, they both measured very close to 1.018440v. Next, I wanted to measure the difference between the two on my HP 419A, I was surprised to see only about 500nv diff once the 419A was nulled! These are just toys, something to play with. Oh, one of the cells came from Honeywell where it had been on a shelf in the lab for 30+ years, this one came with a mint 1968 Eppley manual/catalog with data and price sheets.
Scanned Eppley 1968 manual/catalog with price sheets;
https://drive.google.com/file/d/1eBw50tLOK7VMq5tzayuk0NW7EneqIlTO/view?usp=sharing