What is the voltage reference part in the Fluke 87 V? - Page 1
Forum section: electronics / beginners

author: samgab
author_rank: Frequent Contributor
timestamp: December 22, 2011, 08:00:21 am
content: Hi, I was wondering what is the voltage reference component in the Fluke 87 V?Which is the specific precision component that gives it it's 0.05% basic DC Voltage accuracy rating?Cheers.

author: grenert
author_rank: Frequent Contributor
timestamp: December 23, 2011, 12:30:13 am
content: I think most of the Fluke handhelds use a bandgap reference (not sure the specific one in the 87V).

author: The_Penguin
author_rank: Regular Contributor
timestamp: December 23, 2011, 01:28:21 am
content: Quote from: grenert on December 23, 2011, 12:30:13 amAccording to the service manual it's a 1.23v 60ppm band gap LM285bxz-1.2d26Z

author: samgab
author_rank: Frequent Contributor
timestamp: December 23, 2011, 01:56:15 am
content: Quote from: The_Penguin on December 23, 2011, 01:28:21 amCool, thank you. Is that Service Manual for the original 87, or the 87V?... Online I could only find the PDF for the service manual of the original 87, which seemed to be quite different in quite a few ways.

author: The_Penguin
author_rank: Regular Contributor
timestamp: December 23, 2011, 02:13:04 am
content: Quote from: samgab on December 23, 2011, 01:56:15 amProbably the original. Now that I look more closely (just got it an hour ago) the manual (PDF from the guy who sold me the 87-V on eBay) looks pretty old. It says rev 5 3/96

author: samgab
author_rank: Frequent Contributor
timestamp: December 23, 2011, 07:56:51 am
content: Quote from: The_Penguin on December 23, 2011, 02:13:04 amHmm, yeah '96, that'll be the original. It'll have info in it about calibrating (adjusting) using trim pots, which the 87V doesn't have. Quite a few of the components looked quite different so I'm not sure if they are still using the same voltage ref.

author: EEVblog
author_rank: Unknown
timestamp: December 23, 2011, 10:29:53 am
content: Quote from: samgab on December 23, 2011, 07:56:51 amThe original 87 was introduced at least as early as 1988:https://www.eevblog.com/forum/index.php?topic=354.0http://assets.fluke.com/manuals/87______umeng0800.pdfThe 87-III was around 1997http://assets.fluke.com/manuals/8xiii___umeng0500.pdfSo yeah, a 1996 vintage model would be the original.Dave.

author: Richard W.
author_rank: Regular Contributor
timestamp: December 25, 2011, 10:26:49 am
content: Does somebody know which reference is in a Fluke 289?

author: Marco1971
author_rank: Contributor
timestamp: July 22, 2018, 12:34:09 pm
content: Hi Richard, possibly a Linear Technology LT1019 in smd technology.http://www.analog.com/en/products/analog-functions/voltage-references/series-voltage-references/lt1019.htmlMarco.

author: bluey
author_rank: Regular Contributor
timestamp: June 06, 2020, 04:00:42 am
content: Quote from: samgab on December 22, 2011, 08:00:21 amIf anyone is still curious, the service manual for the 87-V/AN says its a LT1790ACS6-2.5. 87-V specs say DC accuracy is +/-(0.05%+1).https://www.analog.com/media/en/technical-documentation/data-sheets/1790fc.pdfI can't find a voltage reference part for 87-IV, but basic DC accuracy is quoted as 0.025%.