[volt-nuts] 732A and Prologix received

[Don@True-Cal]

Hi Charlie,

Yes, in the summer time my lab runs between ~24.5 & 26.5 C with an occasional excursion beyond either of those limits on extreme days. It is a basement (walkout type) lab with ceramic tile floor which helps account for the muted extremes, and also not having an extreme hot or cold attic overhead. See the link for a lab temperature graph over several days including the last day of the summer voltage run I provided earlier. Since the 3458A accuracy is +/- ~0.5 PPM over typical lab temp extremes, I maintain a database of lab temp, 3458A ref 10.0V readings and 3458A internal temp so I can always refer back if doing a critical voltage transfer. The computer program not only does the graphing but also logs the raw data. While logging, I use lower (100 or 200) NPLC settings so my raw data resolution provides more detail for other types of post processing. But even when doing a voltage transfer, I never see an advantage, and don't use an NPLC setting over 300 (5-min). I would love to maintain the standard 23C lab temp but in the summer months here in the Midwest US, that gets too expensive. Winter temperatures are centered fairly close to 23C. The lab temperature graph link shows four PRT sensors, one is simply in open air thus subject to the same air currents as all instruments while the remaining three are in two different temperature dry-wells (powered off of course) that contribute considerable thermal mass.

https://www.dropbox.com/s/r5vl3v0k3s9t8n1/Lab%20Temp%208-22%20to%208-30%202014.pdf?dl=0

Don

-----Original Message-----
From: volt-nuts [mailto:volt-nuts-bounces at febo.com] On Behalf Of Charles Black
Sent: Friday, August 29, 2014 3:44 PM
To: Discussion of precise voltage measurement
Subject: Re: [volt-nuts] 732A and Prologix received

Hi Don,

I'm a bit of trouble sending you this message for some reason. Maybe the third ti me is the charm.

Thanks for sharing the graph a few days ago. My 3458A graphs look about the same except I only do voltage so far. I use NPLC 1000 which looks smoother but doesn't really have any additional useful info. I have been meaning to have my TEMP? servoed  some time in the near future. My TEMP? 
runs about 37C at a room temp of 23C. Is your room temp a bit higher?

Charlie


On 8/29/2014 1:36 PM, Charles Black wrote:
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