[volt-nuts] HP 740A

Pete Lancashire pete at petelancashire.com
Sat Oct 13 22:05:07 UTC 2012


Here's the introduction article

http://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1965-05.pdf

Being a collector of various instruments, if I had it would be keeper.
But only for
its context of a 1960's instrument.

If you plan on playing with it, you will want to make sure the dual
oven works, like
many ovens of that time and even later it more then likely is not fail
safe. It can
stick 'on'.

It would be interesting to see how much the zener has driffect in 40+  years.

The missing bias cell can be replaced with an IC reference.

-pete


On Sat, Oct 13, 2012 at 2:49 PM, ed breya <eb at telight.com> wrote:
> I recently acquired for cheap an old HP 740A DC standard/voltmeter of 1960s
> vintage. It seems to be pretty clean inside and complete except for missing
> a small bias cell. I'm trying to find a manual - found the "B" version one
> so far at hparchive.
>
> Before putting in much effort to fire it up, does anyone have opinions on
> whether it's worth keeping and fixing - does it have decent performance by
> today's standards, so to speak? There's a sticker inside that showed that
> (sometime in the 1960s) the reference deviation was no more than +/- 5 ppm
> recorded over a four week period, under some kind of test conditions.
>
> Ed
>
>
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