Hey guys! So I've only currently have two DMMs a Cheap-O Innova 3300, and a AMPROBE AM-520, obviously I can't yet afford anything better. However I am a bit of a stickler when it comes to accuracy. Is it worth trying to calibrate these to be as accurate as possible? Or just wait until I get something better and just use these as is.
Hey guys! So I've only currently have two DMMs a Cheap-O Innova 3300, and a AMPROBE AM-520, obviously I can't yet afford anything better. However I am a bit of a stickler when it comes to accuracy. Is it worth trying to calibrate these to be as accurate as possible? Or just wait until I get something better and just use these as is.
You might want to think hard before you enter these waters. Others have found this an expensive habit to support.
Fortunately, the first steps are free. You say you are a stickler for accuracy. Have you fully defined what you mean by that? If your meters meet their specification will you be happy? Do you understand how the specifications are written and what they mean over the ranges of the meter? Do you want each displayed digit of the meter to be correct? Under what operating conditions? Will performance verification at a small number of operating points be satisfactory to you? What do you mean by correct? Most of these questions don't have absolute answers, they are mostly determined by your personal needs and desires. After you have answered these and other questions you will be better prepared to go further down this road.
If you do you will find much friendly support on this and other calibration threads.
Seems like I won an auction for 10 VRE3050 voltage references. I want two. The rest are available to club members for what I paid plus shipping.
https://www.ebay.com/itm/132499240091
Let me know.
Randy
Hey guys! So I've only currently have two DMMs a Cheap-O Innova 3300, and a AMPROBE AM-520, obviously I can't yet afford anything better. However I am a bit of a stickler when it comes to accuracy. Is it worth trying to calibrate these to be as accurate as possible? Or just wait until I get something better and just use these as is.
You might want to think hard before you enter these waters. Others have found this an expensive habit to support.
Fortunately, the first steps are free. You say you are a stickler for accuracy. Have you fully defined what you mean by that? If your meters meet their specification will you be happy? Do you understand how the specifications are written and what they mean over the ranges of the meter? Do you want each displayed digit of the meter to be correct? Under what operating conditions? Will performance verification at a small number of operating points be satisfactory to you? What do you mean by correct? Most of these questions don't have absolute answers, they are mostly determined by your personal needs and desires. After you have answered these and other questions you will be better prepared to go further down this road.
If you do you will find much friendly support on this and other calibration threads.
Lets just say at this point I'd be extremely happy in knowing that the readouts of my DMMs are showing me what I should be seeing. So if a 5.204 volt source where being measured, it'd come out as 5.204. The Innova 3300 has been rather old, so I calibrated it to the AM-520 reading because both did not want to agree, they were separated by a couple hundred millivolts. However I'd sleep better knowing that if read by accurate DMMs they'd all give the same output.
Sure. I have received several emails from an intermediate shipping agency saying “on the way”, “don’t panic” and “still on the way”
Randall
I never thought that with a ceramic package I would get 200uV change with mechanical stress.
Question for the group:
Should I just make these the nominal value and keep it simple, or should I go with a slightly smaller / larger value and add a trimming circuit? (e.g. should my 10K be 10K +/-0.1% or 9.99K + trimming circuit?)
Which brings up another question: for a 4-wire connection, is it important to have low-thermal-emf jacks for all four leads, or just two of them? My intuition says that the sense leads are voltage-mode, but the force leads are current-mode, so a few uV of thermal EMF on the force leads doesn't matter at all (so use the Pomona 3770's on the sense leads, and use cheaper brass jacks on the force leads). Thoughts?
@cellularmitosis: Would you mind sharing the Heater-PCB? Looks nice for Hammond-cases. Is it a single supply design?
On another note, I'm also trying to cobble together some resistance transfer standards for the club.
I got lucky on ebay and scored a GenRad 1434 for super cheap which we can use as a donor for our resistance transfer standards!
The 1434 appears to be a later, cost-saving model compared to the 1432 and 1433:
I also got incredibly luck with the 1432 ($39 shipped!), but paid dearly for the 1433 ($200 shipped).
Does your 1432 have brass , or silver contacts?
Yeah, that's significantly different from the older ones I'm accustomed to seeing. Wow, good to know.