[volt-nuts] Calibration of voltage standards

[Todd Micallef]

A Data Proof scanner seems to be the standard of some primary labs. They
don't show up often on the auction site.

This company makes one that fits the front of a 732B. I have never seen it
in use.

http://www.hpd-online.com/reversing_switch.php

There also appears to be a Guildline 9600 up for auction. It is misspelled
Guideline. I don't know the specs of that item, I have just noticed it has
been listed for a while.

Some of the Keithley instruments take "low thermal" cards, but they are not
reversible as far as I can tell. You might be able to do so with two
separate inputs. It is a Keithley 7168 nanovolt scanner card. If you can
get one, I am pretty sure you can plug it into a 7001/7002 scanner.

A home made switch might be cheaper if you can source some good low thermal
latching relays.

Todd

On Wed, Feb 11, 2015 at 12:35 PM, Ken Peek <ken.peek at diligentminds.com>
wrote:

> I forgot to mention that I also own a PPM Inc. Model AVM-100 null meter.
> Works great on AC but I need to replace the NiCd batteries for it to
> work on batteries.  It has a 1uV scale, and it is a bit noisy on that
> scale.  I intend to modify it to get batter 1/f noise specs on the 1uV
> scale.
>
> Does anyone know where I can get [or how to make] a low-thermal-EMF
> switch [or relay]?  This would need to be a DPDT type to be able to
> reverse the connection to the meter.  Ideas?
>
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