[volt-nuts] Agilent 3458A Positive Experience

J. L. Trantham jltran at att.net
Mon Feb 13 02:19:31 UTC 2012


The 'home-cal'd' unit 'failed' on only the 'AC VOLT High Freq' for the 10 V
Range with 3 V input at 4 and 8 MHz.  3 V input at 2 and 10 MHz passed along
with all values at the 10 mV, 100 mV, and 1 V ranges.  I used an
uncalibrated HP 3326A, a short piece of RG58 and a Tektronix 50 ohm load to
a BNC to Banana adapter.  Both 4 and 8 MHz failed with an over reading by
about .12 V at 4 MHz and .22 V at 8 MHz.  This suggests that my 3326A
outputs a slightly low amplitude at those frequencies.

All other ranges were cal'd using my Solartron 7081 as a 'transfer standard'
reading my Fluke 731B at 10 V and a Gray Instruments 10 K resistor.  I have
to say that calibrating the 3458A was quite easy, following the instructions
in the Calibration Manual, much easier than calibrating my 3478A that I did

The Agilent unit failed all of the DC VOLT GAIN except the 100 mV range with
+100 mV input.  The -100 mV input and both + and - inputs for the 1 V, 10 V,
100 V, and 1000 V ranges all failed, though it was very close, all ranges
being off by about 4 ppm.  According to Agilent, all other measurements
PASSED in the 'As Received' category.

Prior to sending them back, I did notice that the Agilent unit read my 731B
10 V about 10 uV higher than the HP unit, even before I 'home-cal'd' the HP
unit.  The HP unit and my Solartron 7081 seemed to agree with in 2 or 3 uV.


-----Original Message-----
From: volt-nuts-bounces at febo.com [mailto:volt-nuts-bounces at febo.com] On
Behalf Of Marv Gozum @ JHN
Sent: Friday, February 10, 2012 1:15 PM
To: Discussion of precise voltage measurement; 'Discussion of precise
voltage measurement'
Subject: Re: [volt-nuts] Agilent 3458A Positive Experience

This is great to know Joe.  Just curious, 'home cal'd' 3458a sounds 
like a challenge.  When you say 2 of the AC ranges were off, which 
ones?  Do you have a variable AC voltage and frequency source to use, 
or did you use some other substitute?

With the Agilent unit DC gain needing adjustment, did the any DC or 
ohms functions read off specifications before the Agilent was calibrated?

At 09:09 02/10/2012, J. L. Trantham wrote:
>requiring me to 're-cal' the meter using 'in house'
>After leaving the meters on for several weeks, with all functions 
>seemingly correct, I sent both to Agilent for their Agilent Calibration 
>for $579.81 each.  Both passed (with my 'home-cal'd' unit being off on 
>only 2 of the AC ranges and the Agilent unit being off only in the DC 
>Gain) and were returned in about 10 days, amazingly fast.

Best Wishes,

Marv Gozum

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