Started with the calibration checks of my collection of DMM's. I drew up a generic form that can be applied to all of them and will kept as a record. First up for cal is the Fluke 87 Series 1. Which took all of about 10 minutes to complete.
I've never had to make any updates to the 87 since purchasing it in 1997. It just works and stays in cal. Change the battery when needed and it's good to go. ![ThumbsUp :-+](https://www.eevblog.com/forum/Smileys/default/icon_smile_thumbsup.gif)
That 8021B just chilling in the background, I really need to get one of those just because... Specially one build in the same year I was born!
Fluke 8021B calibration. The “BT” indicator was on. Weak battery, replaced. Other than that calibration for all parameters was dead nuts. No adjustments required.
med, what are you using for a calibration source?
A bunch of things. I have two AD-584-M references but they only cover 2.5V, 5.0V, 7.5V, and 10V. As you probably are aware most DMM's for DC cal require a precise 190mv, 1.9V, and 19V source. I have a home built unit that uses both AD-584 references in series to produce these precision references. I've posted the schematic before but if you need it I can post it again.
For a 190VDC source I have a home built unit that uses a Smakn DC-DC converter to generate 220VDC which feeds a Microchip LR8 regulator set to 190VDC. It's not extremely accurate but it's real close (within 1V) and I monitor with my bench reference and compare the readings. I can post that schematic too if you want it.
For 1VAC / 60Hz I have a reference I built over 30 years ago that was part of another DCV reference that I no longer use as it's not as accurate as my current DCV reference.
For ohms I have a 0.1% decade box built up that goes from 1 ohm to 10M.
I have plans for a 500VDC reference that I just haven't gotten to finish yet.
Edit....the 190mV, 1.9V, and 19V reference is posted on page 1 of this thread under "electronics miscellany"