Difference Between Kelvin-Varley Dividers - RV726 vs Fluke 720A

Started by Hawaii596, 04-05-2013 -- 15:15:03

Previous topic - Next topic
Print
Go Down Pages1
User actions

Hawaii596

04-05-2013 -- 15:15:03
In process of setting up standards lab, I have two Kelvin-Varley dividers:  An ESI RV726 and a Fluke 720A.  The one GIDEP procedure I looked at is for both of them.  I'm trying to determine which, if either, is the better model.  Or are they virtually identical regarding specs?  Anyone have experience or knowledge of both and care to render an opinion as to the more preferrable of the two.  In lieu of any spec differences, I'll attempt to cal both and see which if either seems more stable/repeatable than the other.
"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

Pylarinos

#1
04-09-2013 -- 16:17:26
 Hi, I have  used and calibrate Fluke 720A voltage divider for many years is a very accurate and stable divider. To calibrate it, you need a null detector or a DC voltmeter 6 ½ digit connected for differential measure, a lead  compensator and an SR1010 resistor  or identical and certainly low thermal leads. You can down load the manual from Fluke if you haven't done so.

Hawaii596

#2
04-10-2013 -- 12:56:37
Yes, I do have all of the items you listed.  I'm hoping someone here has experience with both the 720A and RV726 to render an opinion which (if either) may be the better.
"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

USMC kalibrater

#3
04-11-2013 -- 04:33:29
I prefer the Fluke with that said though, I have used it with far more frequency that all other dividers combined.
Jason
"Be polite, be professional, but have a plan to kill everybody you meet." -General James Mattis

Bryan

#4
04-11-2013 -- 12:30:24
I don't have either but just pretended I wanted one. 
I can get a 720A new or used.  New (to me) means parts & support are available. 
As for the RV726 not so much luck, ESI seems to have moved to different products, doesn't seem to have migrated the GenRad/IET with resistor products.  Maybe some else has it now. 
Probably not a piece prone to failure but worth considering.

Hawaii596

#5
04-11-2013 -- 15:27:51
Good point long term.  I guess the 720A is still in production/support.  Whereas the RV726 is not.  One noteworthy point is that I found a K procedure in GIDEP that is a cal procedure for both, and there was no differentiation in specs (i.e. both cal'd to same tolerances).  So all things being equal, that leans a little toward the 720A.
"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

John Treekiller

#6
04-11-2013 -- 16:59:05
I would have to agree with Bryan as to using the Fluke.  The AF TOs are different; 33K8-4-2-1 for the RV722 and 33K8-4-529-1 for the Fluke.  The TO for the RV722 is so old that you're instructed to create a Venitian Blind Graph for the first decade to track Linearity.  I'd never heard of such a thing until I calibrated one at an AF Lab.  The Table 1 specifications in each TO look close, but the RV722 have some weird extra specs.  Some kind of effective listing of specifications; I'm depending on my memory here and thats pretty shot.  If you have GIDEP access you can see what I mean.

Hawaii596

#7
04-12-2013 -- 10:10:18
Not sure spec differences, but mine is an RV726.
"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

John Treekiller

#8
04-12-2013 -- 17:52:55
I guess I'm really getting old.  Maybe the RV722 was just lingering in my memory as a bad experience.  I'll have to check next week to see if the AF calibrates the RV726.  Sorry about the mistake.

Hawaii596

#9
04-15-2013 -- 11:38:27
Best info I have is at least on GIDEP, there is a joint procedure that covers the 720A and RV726.  And they don't differentiate on specs.  That is covered in a Navair = AE64.  There K procedure is K8-4-892 (covers the RV726 only).
"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

#10
04-24-2013 -- 11:28:14
We're getting a lot of model numbers thrown out here, so let's get them straight!

The ESI RV722 is a 1 ppm of input box, with all internal resistors in free air.

The ESI RV726 is a 0.1 ppm of input box, with both 'A' and 'B' decades in a sealed oil can for improved TC.

The Fluke 720A is a 0.1 ppm of input box, with the 'A' decade in a sealed oil can and the 'B' decade using equal/opposite resistors for improved TC.

The ESI RV726 and Fluke 720A were designed by the same person, to the best of my knowledge.

The specifications for the 720A and RV726 are identical; I can't speak to the actual performance of each, however.

Hawaii596

#11
04-25-2013 -- 11:15:34
This is all probably going to come down to when I test them, which, if either is in better condition; or if either needs repair.  Still slightly leaning toward the 720A due to I believe it being a still current model..
"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

#12
05-06-2013 -- 11:56:26
Quote from: Hawaii596 on 04-25-2013 -- 11:15:34
This is all probably going to come down to when I test them, which, if either is in better condition; or if either needs repair.  Still slightly leaning toward the 720A due to I believe it being a still current model..

That's correct, Hawaii, the Fluke 720A is still in production and is fully supported.

Karl

#13
05-06-2013 -- 19:34:49
Tap the adjustment resistor & switches when you get a null.
It may help you id a bad unit.
Print
Go Up Pages1
User actions