On Wednesday, May 17, 2017 at 7:24:32 PM UTC-4, Jim Wilkins wrote:
"Jim Wilkins" wrote in message
news
"Garrett Fulton" wrote in message
...
On Wednesday, May 10, 2017 at 6:40:09 PM UTC-4, Jim Wilkins wrote:
................
However my flea-market 1970's Fluke 4-1/2 and 5-1/2 digit bench
meters
are still within spec when measuring a 10V calibration standard.
-jsw

I've got 3 meters I'd like to check for calibration. Is that 10V
calibration standard something that costs an arm and a leg?

Garrett

https://www.amazon.com/DROK-Precisio.../dp/B00NL419KW
The reference IC is really an AD584.
Its hand-written label indicates that it measured 10.00222V on an
Agilent 34401A at 21C in 2015. My Fluke 8800A (no cal?) shows
10.0017/18, the Fluke 8600A (1995 cal) shows 10.002V.

-jsw

My house is now at 22C so as promised I rechecked theAD584 reference
against the 5-1/2 digit Fluke, after an hour warmup which decreased
the Fluke's initial 11 microVolt zero offset to +/-0.
Using an analog variable power supply, the Fluke reads +10.0018/19
with 12V powering the standard, and +10.0021/22 with 18V powering it.
It starts to droop below 10.0018 at less than 11.0V in.

I'd say that a more convenient 12V A23 battery clipped onto the board
is fine for adjusting 3-1/2 and 4-1/2 digit DVMs and the AD584 only
benefits from two dangling 9V batteries with a 5-1/2 digit meter. Up
to 30V is permitted. At 27V the Fluke still reads +10.0021/22, but
lingers longer on 22.
-jsw

I got one of these boards. Hooked it up just now to a bench supply at 15V. I checked one of my three Fluke 8840As that hadn't been calibrated in over 20 years. Holy crap dead nuts on target. Fluke builds some serious stuff.

And, for giggles, the Centech POS they were giving away at HF reads: 2.49, 4.99, 7.48, 9.98. Not nearly as bad as I expected.

Later, I'll check some more meters. But so far, I'm happy that I got the reference board, it confirms that my "reference" meter can still be trusted, and I needn't pay for calibration unless a particular job demands it.