Whether or Not to Maintain A Ballantine 1395B when I have a Fluke 5790A

Started by Hawaii596, 08-03-2010 -- 10:42:12

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Hawaii596

08-03-2010 -- 10:42:12
Without going in and doing the numbers, anyone have a quick opinion about the desirability to continue to maintain a 1395B (50 Ohm 1 Volt) if I have a Fluke 5790A in service. 

BTW:  I also have a semi-mothballed Fluke 792A that I may be bringing back into full service in the next year or so (it was cal'd through 2005, and has been kept plugged in since).  I also have a Datron AC standard I haven't decided what to do with yet.
"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
08-03-2010 -- 12:14:10
Probably not but it depends, the 5790A wideband goes to 30 MHz, the 1395 to 100 MHz I believe.  Question becomes do you need that or can you take over with power meter & sensors above 30 MHz and get what you need.

despite having a pair of 5790As I still maintain one thermal converter, sometimes you just gotta measure at the output & a cable causes problems.

Hawaii596

#2
08-08-2010 -- 17:05:16
I am actually taking over with power meters and sensors - at about 10 MHz.  I use the 5790A up to 10 MHz.  Then I do a transfer at 10 MHz with an 8482A/436A.  And I only do  a few units a year where that area of flatness is covered.

Sounds like my 1395B needs to continue to be a desk decoration for me., 
And the OLD Fluke TVC (maybe its an A40 series 3V/50 Ohm - I'm at home now).

I'm VERY SLOWLY working on bringing the full standards lab on line (Guildline 9975 with Thomas 1 Ohm and SR104 10K; Fluke 792A, a bank of 10VDC references, dividers, etc.; and of course, my 792A (I should probably do some "dry run cals" with it just to get some confidence it is still working properly). 

The two biggies right now are getting the 9975 running and replacing all the batteries in my 10V refs.

Back to Sunday - no work stuff.
"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

metrol12

#3
08-20-2010 -- 11:00:33
A 5790A is practical for a laboratory that will certify alot of calibrators.   (5700A/5720A, 5500A, 5100A/B, 9100A, 4807/4808 etc. )  But costs nearly $5k in budget dollars to have ceritified. (annually recommended)  And more if repairs are required.

Thermo-converters are more econimical if using for just flatness testing of LF generators as it is easier to use, less cost in certification (2 year cycle), and repair.

I have two set of thermo-converters and had a 5790A.   The ROI of the 5790 was not worth having it.

Hawaii596

#4
08-22-2010 -- 12:57:59
It's kind of a given that we'll have our 5790A operating.  So the question ends up being whether or not to add the cal expense of a mothballed 1395B 1V 50 Ohm to the budget.  The other detail is that one fine sunny day, when I get me 792A back out of mothballs, we can cal the 5790A with it (oversimplified comment).  And I only have the one 1395B (very limited voltage range).
"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

MC Devastator

#5
08-24-2010 -- 11:12:20
You have to take into consideration the time involved calibrating a thermo converter prior to cal.   The 5790 is fast and is just too easy for major standards.

But in the end, if your lab doeswn't handle many high end standards, then its not worth your time or money.    But, having the 5790 opens up avenues to add more work to off set the future costs of that standard.

Hawaii596

#6
12-06-2010 -- 13:28:49
We have an odd set of circumstances.  We have a Fluke 5790A that we keep in cal.  We do use it moderately.  But I have an oddball automated cal procedure that uses a 1V and 3V 50 Ohm TVC for a check (I think for an HP 3325B maybe??).   So I ended up sending my Ballantine 1395B 1V and an older Fluke cylinder shaped TVC with GR-874 connector out to Ballantine.  I also have a Fluke 792A that is out of cal right now, but was in cal continuously up to about 2008, and my electrical standards lab is in progress of being readied (very slowly) to come on line  --- that is a long story.  So, bottom line, these TVC's I think will help me some in establishing my numbers, I need to keep continuous cals on the 5790A for historic drift purposes, and the TVC's are a money saver for some automated cals.  And regarding the Fluke 792A, once that is back in cal, it will be king of AC for this lab.
"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

#7
12-06-2010 -- 14:46:18
The Fluke cylindrical piece is an A55, not for sure but I think the input Z is not 50 ohms like the ballentine or Agilent 1105x series, found an old sheet saying approx 200 ohm per volt, I alway figured they were more matched up to AC Calibrators than normal 50 ohm test equipment. 
We use 5790A wideband for 3325A/B flatness, works well enough, obviously use a decent and relatively short cable.
I have not been able to get the 5790A to work good enough on place of the thermal converter for the 8904A and am still using agilent T/C for that app.

WestCoastCal

#8
12-06-2010 -- 15:08:29
The 5790A has GPIB, we have found some excellent efficiencies using it with automation scripts where our 8508A is not accurate enough.  Calculating corrections with a TVC is prone to human errors.  Obviously this only good for <30 MHz

Hawaii596

#9
12-06-2010 -- 16:01:21
The only place we will probably use TVC's is in automated procedures, where we have the coefficients already programmed in.  I don't much care for them.  But.... in automated setups, they are sure quicker.  Especially if there isn't an automated procedure using the 5790A.
"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
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