[volt-nuts] Traveling Standards

Thu Sep 1 12:22:09 UTC 2011

Hi Greg,

No, I am not working in electronics, just hobby so I'm not a interesting
custommer for them. I needed parts for my 720. I mailed the service
department, I got a mail returned it was handed over to the service
manager and after that no replays, that was the last thing I heard. I do
not think they care much about collectors who are, in their eyes,  no
possible custommer However, I was planning to buy a new 8846A or agilent
at that time. it became a Keithley . I was honnest in my mail and I
wrote I'm a collector and not a company. Maybe that was stupid to do.

Keithley and Guildline are better in that. I mailed keithley about
advise on a good meter for amateur use because the agilent missed some
things I wanted and Fluke... see above, and they phoned me back the same
day to make me a special offer because they liked my
collection/website :-) 
I wrote guildline with questions about the standardcel cabinet and got
mail with an old brochure they scanned special for me from the archive,
technical advise on how to restore the foam in the oven and offered help
if I got stuck.

I have a 731A, the Fluke plan is for the 732. I still not trust my 731.
It is reactive on powersupply changes, it is not a very clean output and
even a 10Meg multimeter causes the output to go a few hunderd uV down.
But it regulates so the reference and opamp must be working. All
voltages are correct. Problem was the batterypack was dead and they
changed thing inside to overcome this. There was a big zener instead of
the nicads but no caps or so and that gave a rather big ripple on the
output. I then placed a 7812 but that was no better, placed bigger caps,
no solution and then I made all original and mounted two nicad battery
packs and then it was a little better but not close to the stability of
my 332. Problem is I do not know what type of reference is insite. Only
a fluke partnumber. 
So I made myself a few references, just as a test. Not with very good
parts but that gave allready better results as the Fluke so I plan to
use the 731 to replace the Vref with the best reference (do not know
whitch one yet) there is (under 50 dollar :-). Get rid of the batterys
and make a very good (external) powersupply after a 7815 using a TL431,
or several parallel and a percision opamp to get enough current and a
stable clean 12V.

Fred

gbusg schreef op do 01-09-2011 om 05:12 [-0600]:
> Fred,
> 
> Do you know anyone at Fluke?
> 
> Fluke Calibration Services (Netherlands)
> http://www.fluke.com/fluke/nlnl/service/kalibratie/default.htm
> 
> Incidentally, in the U.S., Fluke runs a 10Vdc round-robin service (DVMP Care 
> Plan). I'm not sure if that service is available in Europe yet, but as 
> defined it wouldn't meet your criteria due to higher cost and requirement 
> that you have at least one Fluke 732A or 732B.
> 
> ...Still, it might be interesting to know someone at Fluke Netherlands?
> 
> Fluke Direct Voltage Maintenance Program (DVMP)
> http://us.flukecal.com/node/2137
> 
> -Greg
> 
> 
> ----- Original Message ----- 
> From: "Fred Schneider" <pa4tim at gmail.com>
> To: "Discussion of precise voltage measurement" <volt-nuts at febo.com>
> Sent: Thursday, September 01, 2011 1:20 AM
> Subject: Re: [volt-nuts] Traveling Standards
> 
> 
> I am thinking about doing a bit calibrating as a sort of service and to earn 
> some money to spend on calibrating my stuff ( p.e. the 731A transfer 
> standard) with our national standard buro. so not to make money on it, just 
> to cover expenses.
> 
> But he problem is I, have no clue what to ask and if there is. Market. I 
> have a mint condition guildline cabinet with known documented history and 
> from the first user. So I can, after the return of the transfer, compare it 
> with my guildline and have a longtime stable reference. But a calibration 
> here is not as cheap as in the states I think. A friend had a tek current 
> probe calibrated, that was over 500 dollar. But i think most " customers" 
> will have a 4.5 or 5.5 DMM and in that case my cells and calibrators are 
> allready good enough.
> 
> I bought a new calibrated keithley 2000. As soon as It arrived I warmed it 
> up and measured my cells and calibrators , that I allready had warm up, and 
> documented that. The cells where less then 3 uV away from the last 
> documented calibration and still spaced appart like they where then. So for 
> a 5,5 digit i will be close enough. An old secondhand bought 6,5 digit will 
> be closer then it was.
> I have a the 4 cell guildline cabinet, 731A, 332, 750, 760, 720, philips DC 
> volt/current calibrator, and. Fluke 5xx AC calibrator. Besides that a GPS 
> controlled thunderbold Oscillator, a HP 5 MHz standard, counters connected 
> to the 10 MHz ref upto 18 GHz so I can do counters too. Also have timemark 
> en pulsgenerators for scope adjustment but that really is on scopes like tek 
> 7000 or 500 series very much labour if you do not have the calibration 
> plugins. A normal scope is still about 10 hours work.
> 
> The problem is I have plenty of time but i am a bit disabled so I can not 
> work long periods and that means two hours warming up, work an hour on the 
> instrument and rest for an hour so it would take me days. The calibration of 
> my 7704 , witch is rather complex took me two weeks. A simple 547 3 days. A 
> letter plugin about 2 to 4 hours. A DMM like a fluke 8000 or HP3535 is done 
> in about 2 hours, a keithley 199 doing the memory calibration is done in an 
> hour or so but a HP3490 is many hours of work. (and there is the problem of 
> shipping and risk invalved. There can be people trying to missuse your 
> service by sending not functioning gear and telling you broke it or it gets 
> dammaged or lost in the mail.)
> 
> Are there voltnuts how do such project to earn back a calibration. Are there 
> other Dutch volt-nuts here ?
> 
> I do not know there is market for this in the Netherlands. Not much voltnuts 
> around and we Dutch are famous for our cheapiness. I am very active on a 
> very big electronics forum, there are about 4 other volt nuts there, who 
> probably would spent 50 euro or so on a calibration. The rest ( about 80 % i 
> think) use there holy 5 tot 30 bucks multimeter. A 50 euro model is 
> considerd to be rreal expenive and overkill. Cheap is holy around here and 
> being cheap made to an art.
> Lot of topics about Rigol, atten and owen scopes asking if it is wise to buy 
> because it is a lot of money and or if  someone knows a cheaper brand or 
> model  :-(
> But a calibrion is looking what the deviation is, most think a calibration 
> is the same as adjusting it whitin specs. I do that with my own gear and for 
> a lot of gear that is a hell of a job. And to do that for 50 euro does not 
> sound tempting.
> Fred PA4TIM
> 
> 
> 
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