Products > Test Equipment
Old Fluke Multimeters
bd139:
Exactly!
rsjsouza:
--- Quote from: bd139 on August 01, 2020, 04:45:09 pm ---No I used mix of nichicon and nippon chemicon ones picked by value and size from TME. Didn't look for specific capacitors. They don't have to be anything special looking at the schematics.
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Apart from size. Size will matter, especially the ones under the display AND if you are sourcing them from your personal stash. :D
Good job, BTW.
drtaylor:
--- Quote from: bluey on July 03, 2020, 11:45:50 pm ---Some questions for DRT if he is still here:
1. The 8060A release article you wrote describes a buried Zener voltage reference. The manual above says it is a bandgap voltage reference. I thought the two are slightly different. Did the design change somewhere?
2. ELectronics Australia 1990 article describes the general theory and operation of a DMM. (A great read.)
https://www.eevblog.com/forum/testgear/i-need-to-know-the-history-of-fluke-87-(-1998-2010-)/msg3033264/#msg3033264
The generic DMM resistance function is explained as measuring the voltage using a constant current generator to derive resistance. The 8060A and 87 use a ratio compared to a reference resistor, rather than a constant current generator. I presume this simplifies the design wiithout affecting accuracy. 87 has fuse test plus 1000ohms as a sanity check, but the ratio method seens to make this an insane sanity check because it really only checks the reference resistor and voltmeter could be anywhere and fake correct resistance. Interested in your perspective.
--- End quote ---
I haven't been looking at EEVblog forum for a while, and I missed your question. Sorry. The 8060A release article I wrote was heavily edited without my review by a technical editor of Electronics magazine. A number of weird things were incorrect, and I can only guess the editor cut and pasted some stuff from some other meter. One mistake was definitely that the reference is not a buried zener (as you pointed out), but is a band-gap. The band-gap reference was a selected standard Intersil reference (selected for PPM drift). When I was describing the high frequency divider network, I said it had Teflon Trimmer Capacitors, which the editor changed to Teflon trim resistors (which don't exist). It also talked about NPO capacitors, and Ceramic Capacitors. This was silly, since the only capacitors in the divider were NPO (aka C0G) ceramic capacitors. Again a stupid editing error. Early in the article it states it uses a single slope converter...not true, and again a wrongful edit. It uses a dual slope converter which had a unique (at the time) slope multiplying circuit to increase the resolution. Later it does correctly talk about the dual slope converter.
Other minor errors in the article: It talked about the compiler used by the programmers. There was only one programmer, my friend and the "other father of the 8060" Tom Weismann. He tragically died in the 80s, mountain climbing here in Washington State. Most of the rest of the article is pretty accurate, mostly in places where he left my writing intact. So it just goes to show you, that the technical editors are often not engineers, but particularly galling was that the final article was never offered to me or Fluke for checking. I do believe part of this was due to timing to get publicity for the 8060 right before production ramped up. If I went through the article carefully I'm sure a bunch of other errors would crop up, but that ship sailed long ago. I guess it just galls me that some of the stupid errors are associated with my name. Oh well no one is going to read that article anymore, except the few 8060 aficionados found on the forum.
In response to your second question, most Fluke handhelds and pretty much every single chip DMM circuit uses Ratiometric Ohms converters. Basically you integrate with the unknown resistor, and de-integrate with a precision known resistor. This usually uses the same resistors from the input divider. To make high resistance measurements, (displayed in Siemens) the opposite happens: Integrate with the known resistor (usually 10Mohm) and de-integrate with the unknown resistance. The 300MOhm range of the 8060 used this technique, but converted the nS readings back to ohms with a simple 1/X calculation. The monotonicity as the reading got higher would diminish, and we were forced by marketing people to limit resolution so no numbers were skipped. However, there is the power-on sequence that removes this limitation.
Well, I've gotten too long winded again, so I'll stop here. However I would like to announce that I have 15 recapped working 8060s that I would like to sell, but my precision AC source is not working, so I'm unable to calibrate the AC ranges accurately. I've been busy with a Guitar Amp project, and I'm kind of dreading having to go into my Fluke AC Calibrator and figure out what's wrong. Probably needs recapping too. I can confirm all the AC ranges work, but I just can't calibrate them. Anyone who has access to a calibrator that goes to 100kHz could easily calibrate them.
tautech:
--- Quote from: drtaylor on August 04, 2020, 12:36:26 am ---Well, I've gotten too long winded again, ................
--- End quote ---
Never !
Thanks for dropping in again David and sharing with us those times you had with Fluke which if little else give us an insight and a wonderful historical record of those days.
Please carry on.
PS, ever thought about writing a book ?
Very temped to grab one of your meters.....
MarkMLl:
--- Quote from: drtaylor on August 04, 2020, 12:36:26 am ---Most of the rest of the article is pretty accurate, mostly in places where he left my writing intact. So it just goes to show you, that the technical editors are often not engineers, but particularly galling was that the final article was never offered to me or Fluke for checking.
--- End quote ---
If it's any consolation, I was discussing "this and that" with one of the BBC science journalists a few years ago and they have the same problem: carefully-written articles mnagled by non-technical editors (often /young/ non-technical editors, with media studies degrees).
MarkMLl
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