[volt-nuts] Valhalla 2703B

gbusg gbusg at comcast.net
Sat Apr 2 01:51:53 UTC 2011

Well, 20ppm aggreement at 1kHz is indeed spectacular! IIRC, the 3458A ACSYNC 
spec is approx. 92ppm at 1kHz 1V. In actual practice I've observed many 
3458A's to be within 7ppm at 1kHz 1V. However I've seen some measure in the 
range of 17 or 19ppm error. A bigger issue occurs at higher frequencies. At 
20kHz some 3458A's look pretty good, while others might be off as much as 
130ppm, depending on settling time after you first switch to the 1VAC range.

The 3458A's claim-to-fame for AC mostly relates to frequencies below 20kHz. 
It degrades as we approach 100kHz. It's not surprising you see strange 
differences of dependencies of combinations of lead/ground configurations at 
100kHz according to different serial numbers of 3458A (same goes for 
combinations of different serial numbers of AC calibrators and 3458A's).

Anyway, I can only hope my 2703B will perform as nicely as your unit. (But 
I'll expect something worse, so as not to be too dissapointed!)


----- Original Message ----- 
From: "Mark Sims" <holrum at hotmail.com>
To: <volt-nuts at febo.com>
Sent: Friday, April 01, 2011 3:45 PM
Subject: [volt-nuts] (no subject)

I have the 3458A's set to ACSYNC (but there is not much difference with 
normal mode readings). With the 2703 set to 1.00000V at 1KHz, two of the 
three 3458A's read within +/- 20 uV. Same general error percentage at 10V 
and 100 V. I haven't done a lot of testing at odd voltages. I may try to get 
Swerleins's algorithm up and running on my GPIB computer. The other 3458A 
needs to be hardware calibrated... I'm waiting for the room temp to get a 
little warmer before dragging out the 732B and SR104.

Things start getting weird at 100 KHz. I found a one combination of 
lead/ground connections on one of the 3458A's where the reading does not 
change much between 1KHz and 100 KHz. Most combinations and the other 2 
3458A's have around a 400 uV change between 1KHz and 100 KHz. The error at 
10 KHz is not much different than 1 KHz/100 Hz.

There would be a problem fully calibrating the 2703 with the 3458A... the 
3458A only goes to 700 VAC. The 2703 has a 1000V calibration step. I could 
fire up the Fluke 540B, but that thing is a royal PITA to use.

0.005% at what voltages and frequencies? (Of course 3458A ACSYNC specs are
worse than 0.005% at mid-band audio, although better than the 2701B's
specs.) You're setting your 3458A's to ACSYNC mode, right? ...and running
ACAL ALL first?
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