ESI 242D Resistance Measuring System - Is It Worth Reviving

Started by Hawaii596, 11-28-2012 -- 07:48:20

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Hawaii596

11-28-2012 -- 07:48:20
In my company's storage area, I was just told about an old ESI 242D Resistance Measurement System.  I have Fluke 8508A's, HP 3458A's, two Guildline 9975 bridges that are in process of being activated.  Is the ESI 242D system worth the effort?  Or should I just rob it of the RS925 decade (those are really nice), and scrap or sell the rest of the system?  I don't have time to research all the specs, so thought I'd toss it out there in case anyone is familiar.
"I often say that when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind."
Lord Kelvin (1824-1907)
from lecture to the Institute of Civil Engineers, 3 May 1883

Bryan

#1
11-28-2012 -- 13:40:22
Ahhh, the nooks & crannies of the warehouse.  I retired mine last year and am investigating the 8508A in the role of a bridge with my my super-cool ESI 104 10K ohm resistor, ditto for the DCV role with a well established 732A reference.  I seem to recall the ESI was around 5ppm or so, the 8508A around 8ppm (95% conf/absolute/12 mo) plus some additional fraction of the range.  I don't have any suggestions at this point as I have not yet run my numbers on it.  Seems like whenever I was testing the ESI I did a lot of trimming on it, based on what goes on around here there wasn't any return on the time I'd spend on it.

Hawaii596

#2
11-28-2012 -- 14:28:58
Spencer says to go slap Nate Dog up side the head....

Thanks for the input.  I did a quick look and saw at least according to a brief spec it is supposed to be about 10 ppm direct reading with as good as +/-1 ppm using for comparison.  There is that balance between how much pain its worth versus specs.  I think it also has a divider on it that might be worth salvaging.  I think I remember you assisted me a while back with an LISN procedure.  Thanks again.  Have a good one.
"I often say that when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind."
Lord Kelvin (1824-1907)
from lecture to the Institute of Civil Engineers, 3 May 1883

scottbp

#3
11-28-2012 -- 17:33:28
We have one complete 242D and miscellaneous bits and pieces of other 242Bs kicking around in our warehouse. The 8508A is to the 242D what a scientific calculator is to a slide rule... I hear the old-timers say "I haven't used one of those since I was in the military, and I don't wanna go back."
Kirk: "Scotty you're confined to quarters." Scotty: "Thank you, Captain! Now I have a chance to catch up on my technical journals!"

beadwork

#4
11-29-2012 -- 06:41:05
 Just rob it of the RS925 decade.  I dismantled the one we had here @ Tinker when I got here 3 years ago because we had the 8508A.

spanishfly25

#5
11-29-2012 -- 08:28:21
Is not worth the trouble. the 8509A is easier to use.

Hawaii596

#6
12-01-2012 -- 13:42:14
Nuff said.  I will definitely be robbing it of the RS925 (one of the better decades ever made), and I believe it has a DT72A as well (worth robbing).   Thanks all for the inputs.  We have two 8508A's with the rear input option (Fluke Primary Lab cal).  Not to mention that I am already in process of bringing Guildline 9975's on line.  So based on y'all's confirmations, I'm not going to waste time with the 242D.  I have a major ISO budget expansion project for the next quarter.  Have a great Christmas everyone.
"I often say that when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind."
Lord Kelvin (1824-1907)
from lecture to the Institute of Civil Engineers, 3 May 1883

measure

#7
12-02-2012 -- 19:02:32
As a detector for resistance transfer, the 8508A excels. You don't mention if you also own the various ESI SR1010/30/50/60 transfer standards and associated shorting bars and compensation networks, but using the aforementioned transfer standards, and some advanced metrology techniques related to the Hamon device in general, and the ESI SR10x0 series in particular, sub-ppm transfers can be made using the 8508A (midband, assuming rear input option -01 is installed) as a detector. Plus, the 8508A will source 100 mA at the 1 ohm level, similar to a high-end bridge, as well as doing true current reversals.

Before you toss out the 242D system (assuming you robbed it of the RS925D), take the cover off the 240C Kelvin Ratio Bridge and admire the quality of workmanship that ESI put into those devices when they were manufactured. I was fortunate enough to have had an insider's tour of the ESI factory back when they were still producing these units, and the factory was a thing of beauty, its workers artisans, its products, works of art. Makes me long for the old days!

Hawaii596

#8
12-05-2012 -- 15:53:12
We do have some SR1010's, an SR1050 10 Meg per step.  Don't have the full set of SR1010's, and don't have any of the shorting bars.  I hope to get back into Standards mode after the first of the year.  Going to be working on bringing the 9975 online (two of them and one has the low resistance range extender), and one of them was recently overhauled by MI in Canada.  Hoping to get the overall high accuracy resistance aspect in street legal operation.  I still need to figure some things out for temp stability etc.  On the road for a couple of weeks doing 5720A type stuff, Wtk 9500 type stuff, etc.  Hopefully back to those things in a few weeks.  Have a great Christmas all.
"I often say that when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind."
Lord Kelvin (1824-1907)
from lecture to the Institute of Civil Engineers, 3 May 1883

jeroboambramblejam

#9
12-06-2012 -- 14:54:10
Well, you don't have to plug in a slide rule... The 242D is a shiny black rock!  Decades ago now, I had ours serviced by Tegam/GenRad when the contacts became iffy;  it served well then - even after failure of the 3458A's battery-backed RAM (and associated PCB) made it scrap and ThEy replaced it with a 8508A (Don't get me started).  Also, the old capacitance bridge will still be spot-on when the Wayne Kerr LCR gives up the ghost.

Bryan

#10
04-04-2013 -- 11:48:08
I had some ESI 1010s that needed testing so finally got back to this.  The 1010s were 1/10/100/1k/10k and 100k/step.  I used the 8508A and my ESI SR104 10k reference to start the festivities.  The SR 104 I am confident to assign it an uncertainty of 0.69 ppm.  Applying the 8508A resistance 20 min transfer I knocked the 100k/10k/1k against the SR104 on the 200k/20k/20k ranges respectively, then the 1k became the standard for the 100 ohm step on the 2k range, the 100 became the standard for the 10 on the 200 ohm range and finally the 10 became the standard for the 1 ohm.  My reading of the 8508A "applying the specifications" leads me to conclude in the mode it is best operated within a range.  I did a front divided by rear scan so multiplied the ratio times my standard resistor value and was interested only in type B uncertainty.  I ended up with the following type B.  100k, 3.3ppm/10k, 1ppm/1k,  3.4 ppm/100, 4.7 ppm and 1, 5.8 ppm.   As I went down scale and had to get away from my SR104 and an SR1010 became the reference, the  uncertainties increased.  Also it is my preference to have the reference on the rear input so I can better access the UUT, as a result my ratio readings lost some resolution.  With a lower value reference like the 10k vs the 100k UUT ratios would be 10.000 000 0 but with a standard 10 times higher that the UUT it would read 0.100 000 00.  As I stated I was only looking at type B.  Contributors were limited to Uncertainty of the standard, resolution of the standards reported value, 8508A 20 Xfer specification and resolution of the ratio the 8508A displayed.  Ran those on my Quametec software with a budget and sensitivity coeffecients sheet.  Moving forward I'm comfortable with the 100k/10k/1 k measurements as they could trace directly back to my SR104 (cal'd by NIST since the early 90s).  The lower values relied on other S1010s and I am don't have as warm & fuzzy feeling about thier stability.  I would sure appreciate any feed back if I may have made some kind of error in thought but just wanted to touch base on this issue again.

CalMachine

#11
05-04-2017 -- 13:59:00
I'm curious as to what your end decision was regards to the ESI 242D?  I am currently in the market for one, if yours is available for sale at all.

Hawaii596

#12
05-04-2017 -- 14:22:06
I think its gone. It was a warehouse item, and RS925D and DT72A have been robbed from it. For most needs, I use the 8508A with our SR104. I have a Guildline 9975 that we had refurbished a few years ago, and an oil bath that I will be putting into action in coming months for the higher accuracy resistances.  I do need to go look to see if the lead compensator is still there, and maybe take that, as that may have some value. There are actually some other procedures that ask me to use a lead compensator (characterizing DC as part of calibration of Fluke 5790A's.
"I often say that when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind."
Lord Kelvin (1824-1907)
from lecture to the Institute of Civil Engineers, 3 May 1883

CalMachine

#13
05-04-2017 -- 14:46:01
Quote from: Hawaii596 on 05-04-2017 -- 14:22:06
I think its gone. It was a warehouse item, and RS925D and DT72A have been robbed from it. For most needs, I use the 8508A with our SR104. I have a Guildline 9975 that we had refurbished a few years ago, and an oil bath that I will be putting into action in coming months for the higher accuracy resistances.  I do need to go look to see if the lead compensator is still there, and maybe take that, as that may have some value. There are actually some other procedures that ask me to use a lead compensator (characterizing DC as part of calibration of Fluke 5790A's.

Ahh for sure!  Yeah the RS925 is generally the more sought after item of the 3.  I recently purchased a RS925D and I have a rack mount for the entire system as well....  so really, all I am in need of is the Kelvin-Ratio bridge (240C) and the DC Generator (801).  For the AC characterizations, I picked up a Tegam PRT-73 with the 2.5V/Hz option, so it gives another digit of resolution.  Along with that, I have 2 Fluke 721A lead compensators.

Unfortunately I do not have an SR104 or an 8508, yet.  We do have many other, slightly lower grade, references that I use with our 3458As and 1281.  I plan on investing in a Guildline DCC down the line, but would like to use the 242D resistance bridge until then. 

If you are willing to part with any of your 242D items left, I would greatly appreciate it!
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