USA calibration club

[kj7e]

Is anybody here bidding on this?  I'm thinking of it, but I won't if anyone else is...

My way is always to put in a bid in the last two seconds. I think the current bidders aren't following this forum's ebay bidding thread 

Good luck! Hope the price does not go up much.  If you do get it and need some help I have the full original manual in hard copy plus extra spare caps for the power supply rails.

[cellularmitosis]

Is anybody here bidding on this?  I'm thinking of it, but I won't if anyone else is...

Not me.

I'll abstain from bidding   From the "sold items" search, it looks like a lot of these are listed as $100 or best offer and most of them sold for a best offer, so this meter will still be a good deal in the future for the patient + persistent.

[RandallMcRee]

Hmmm

I'll abstain from bidding   From the "sold items" search, it looks like a lot of these are listed as $100 or best offer and most of them sold for a best offer, so this meter will still be a good deal in the future for the patient + persistent.

So you're saying its already past its sell-by date? I mean, not a good deal at, what is it--$41 + (yikes) 63.65 in shipping?

Yes, you are right, as usual.

[bitseeker]

Yep, t'was what I was jibber-jabbering about. But, of course, different folks have different tolerance for price flexibility. It had exceeded my limits, had I been in the market for one. YMMV

[vindoline]

I just picked up a 3456A for $115 delivered. When it arrived it was the grungist piece of gear I'd ever seen - filthy and sticky (  )all over the outside. Inside it was spotless! Soap, hot water, IPA and magic sponges took care of everything! So far all I've done is a prophylactic re-capping of the power supply. I'm still getting used to it, but I think it's more stable than my Keithley 196. Now that I have two meters, I'll never know which one is right 

[cellularmitosis]

Hmmm

I'll abstain from bidding   From the "sold items" search, it looks like a lot of these are listed as $100 or best offer and most of them sold for a best offer, so this meter will still be a good deal in the future for the patient + persistent.

So you're saying its already past its sell-by date? I mean, not a good deal at, what is it--$41 + (yikes) 63.65 in shipping?

Yes, you are right, as usual.

Ha, no no I just meant I’ll restrain myself from snatching up another piece of gear so that I don’t ruin your good deal with a bidding war .  I think it looks like a great deal.

[bitseeker]

I just picked up a 3456A for $115 delivered. When it arrived it was the grungist piece of gear I'd ever seen - filthy and sticky (  )all over the outside. Inside it was spotless! Soap, hot water, IPA and magic sponges took care of everything! So far all I've done is a prophylactic re-capping of the power supply. I'm still getting used to it, but I think it's more stable than my Keithley 196. Now that I have two meters, I'll never know which one is right 

Good deal, vindoline. Glad to hear it was only a mess on the outside. To know which is right, fortunately you're part of the cal club.

[cellularmitosis]

Ok, I've slogged through a ton of old manuals and I've got a pretty decent crack at what the resistance reference requirements are for a large selection of old 6.5 and 5.5-digit meters:

https://github.com/USACalClub/gear/blob/master/dmms/README.md

Attached is a spreadsheet which summarizes all of the different sets of required references, and which meters require then.

Second attachment is an attempt at consolidating those into a smaller number of mailable "kits" which could be produced, and the meters which would be supported.

This was an interesting exercise.  Requirements vary widely, and many particulars of the limits are often unspecified (e.g. many meters allow specifying arbitrary calibration values, but some of them don't state what the limits are of how far your artifact can deviate from nominal).  Another example was that I had trouble figuring out which meters allow you to just calibrate the Ohms function, and which meters allow you to just calibrate one range of the Ohms function.

With the consolidated set, a few meters would get left out in the cold (assuming they can't calibrate just one range):

- Fluke 8846A (needs a 1G resistor, maybe it allows skipping this value?)

- Keithley 193 (maybe this can use 1.9x values instead?)

- Fluke 45 (the manual states this can use 1.9x values as an alternative)

- Fluke 8808A (appears to require 1R, 10R, 50R, 100R, 150R, 500R, 1k, 1.5k, 5k, 10k, 15k, 50k, 100k, 150k, 500k, 1M, 1.5M, 5M, 10M, 15M, 20M, 50M, and 100M)

(So, potentially, most of those which will be "left out" might be able to use alternate values anyway.)

Also, if anyone has an recommendations for very high value resistors (10M, 100M, 1G) which could be used, let me know (I have no experience here).  Wirewound is probably out, and metal foils don't go that high either.

A relaxed requirement there would be a resistor which is stable enough that it can be used to simply transfer the meter's existing calibration back onto itself (e.g., read the value of the resistor before you start calibration, then enter that same value during calibration).  If a resistor were immersed in a controlled 25C oil bath (+/- 0.01C), we could probably get away with fairly modest resistors for these high values.  The point of including these "relaxed requirement" resistors is that some meters force you to calibrate all of the ranges, so if you are missing 100M, you are stuck.  Being able to improve your calibration on 1k, 10k, etc, and simply copy your existing calibration for 100M is better than not being able to do any calibration.

Let me know if I've left off any important meters from the list so far!  And as always, I'm very interested to hear any feedback here, as I'm pretty inexperienced here.

Thanks!

https://docs.google.com/spreadsheets/d/1VGwU2JbYxnRlgqtmr-_dVEWjddAojWWOSKOFVCrEPf8/edit?usp=sharing

[TiN]

2001 wants 20K (can eat 10K too though, 4wire) and 1Meg (2wire).
2002 wants 1Meg, 200k, 20k, 2k, 200, 20 (all 4-wire).

[ap]

K2002 accepts adjustment resistors starting from 95x

[SirAlucard]

Yeah, most eBay bidders don't know how to bid properly. C'est la vie.

I'm not bidding on that listing, so no worries here.

Looks like it ended up going for well over $200 with shipping, so much for getting it cheap.

[cellularmitosis]

Someone just listed about ten HP 3455a (6.5 digits) units for $75.  Unfortunately he wants $88 for shipping.

[bitseeker]

Oh, the joys of hyper-inflated shipping. It does seem to make for higher overall closing prices. Math is harder while bidding.

[bitseeker]

The point of including these "relaxed requirement" resistors is that some meters force you to calibrate all of the ranges, so if you are missing 100M, you are stuck.  Being able to improve your calibration on 1k, 10k, etc, and simply copy your existing calibration for 100M is better than not being able to do any calibration.

That's a good idea to get through a calibration if you can't skip ranges.

[kj7e]

Someone just listed about ten HP 3455a (6.5 digits) units for $75.  Unfortunately he wants $88 for shipping.

I know its a very subjective opinion, but the more I play with my 3456A the more I think its worth.  Personally I feel $150 - $200 for a clean, working 3456A is a bargain.  Maybe Conrad can comment on the 3455A.

[Conrad Hoffman]

I've got two 3455a units, one that's perfect and has been rock stable for years, the other that has a tiny asymmetry between positive and negative voltages that I've never gotten quite perfect. Since I don't have any other models, I can't say much about different or missing features. One thing I like about the units is you can switch them so they read AC+DC for RMS situations where it matters. OK, it doesn't matter that often. One thing I don't like is they're not very good for low ohms work. The 3478a is way better for that. I've used them both with a Prologix GPIB to USB adapter and they log very nicely.

[RandallMcRee]

Hello calibration club!

Looking for a new (to me) 6.5 to 7.5 digit meter and I see this on ebay:

eBay auction: #https://www.ebay.com/itm/Keithley-2700-Digital-Multimeter-Data-Acquisition-Mainframe-Integra-Series-GOOD/132549221634?epid=1401732325&hash=item1edc8c9d02:g:Jy8AAOSw-RFaXmr3

Its for a Keithley 2700. Is that meter useful without a scanner card? So I could use it stand-alone until such time as a scanner card came into my possession??

Any other suggestions welcome, especially in the 7.5 digit arena up to ~$1000.

[TiN]

I have K2001 in that price range. Can do the calibrate with data (non official, using my standards and calibrated 8.5d meters as reference) prior to shipment as a bonus.

[bitseeker]

Its for a Keithley 2700. Is that meter useful without a scanner card? So I could use it stand-alone until such time as a scanner card came into my possession??

Yes, you can use the K2700 without a scanner card. It's then like a K2000. However, if you don't need the scanning capability, you may want to consider TiN's offer for a K2001 since you're keen on a 7.5.

[RandallMcRee]

I have K2001 in that price range. Can do the calibrate with data (non official, using my standards and calibrated 8.5d meters as reference) prior to shipment as a bonus.

Wow, sounds good.  Will pm you!


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[cellularmitosis]

I picked up a 3457A from ManateeMafia, who has a lab which is remote-controlled by TiN.  TiN did a fully remote calibration of the 3457A using a 57xxA Fluke calibrator, SSH, a ras-pi, webcams, and chat.  It was really pretty impressive!  I've been meaning to make a short post about it -- it was a pretty cool experience.

In other news, I have some good news for the cal club!  I contacted Doug at voltagestandard.com asking how much he would charge to measure an LTZ against his 3458A, and he decided to donate a measurement to the cal club!  I'm about to mail a reference over to him, and I think I'll start mailing that reference around the club after it comes back from him.

Also, my hermetic resistors are on their way back from Andreas, after which I can send a set over to TiN to finish his cal club FX reference.

I know this club has been dormant for a while, but cool things should be coming pretty soon

Edit: I had also contacted the two cal shops in Austin, asking how much they would charge to hook an LTZ up to a 3458a for an hour and give me a CSV file, and both of them basically said "go away".

Edit 2: Ah, blast!  Recently, on ebay, an old 731B went for something like $35, because the description was something like "this was donated to our church, I don't know what it is and most of the screws are missing".  I just realized that I should have jumped on that, because even if it was a gutted 731B, I could have stuffed an LTZ in there and then at least a cal lab would look at it, because it is an "official" piece of equipment, rather than a DIY job.

[kj7e]

I have K2001 in that price range. Can do the calibrate with data (non official, using my standards and calibrated 8.5d meters as reference) prior to shipment as a bonus.

Wow, sounds good.  Will pm you!


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DO IT!

[kj7e]

Doug is a supper guy, I had a similar experience with him and my home built resistor standard.

[TiN]

Also, my hermetic resistors are on their way back from Andreas, after which I can send a set over to TiN to finish his cal club FX reference.

Great, this will be first external FX reference to go in wild.
My resistor order is due July, so schedule slips on those units. I'll have update for rest FX units soon.

[nikonoid]

Actually, even if you need scanning, you can get a scanner card for 2001. Sometimes they sell for as little as $50.
It is a very good offer, especially for a unit that was verified working correctly and calibrated.


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