Also of note:
There is a design flaw if you have some kinds of probes: it is possible for your probe inserted into the right side connector to contact two terminals of a chip underneath it, shorting them out. It didn't appear to cause damage, but it still should have been prevented.[/li][/list]
Also note - the OPs reference has the lower spec'd AD584kH chip. Some of these are sold with the higher spec'd AD584LH chip.
Also note - the OPs reference has the lower spec'd AD584kH chip. Some of these are sold with the higher spec'd AD584LH chip.
It seems the people behind L-type are cheating. All units have the same printed test report :--
https://www.eevblog.com/forum/metrology/are-cheap-ad584-units-worth-it/msg920924/#msg920924 (https://www.eevblog.com/forum/metrology/are-cheap-ad584-units-worth-it/msg920924/#msg920924)
It seems the people behind L-type are cheating. All units have the same printed test report :--About a year ago I bought the AD584LH version about a year ago from ebay seller 201377jie. It came with a paper with cal data very similar to the paper discussed in the thread you linked to, with the exception that the voltages were handwritten. I checked it against my HP 3455A and after having the room heated up to 23oC (like indicated on the cal sheet) and having the meter turned on for about an hour the voltages measured by the HP3455A were surprisingly close to what was on the cal sheet, only a few counts difference at most.
Cal sheet | HP 3455A (Vin=18.0 V, T=23.5oC ) | |
2.5V | 2.50194 | 2.50197 |
5.0V | 5.00326 | 5.00327 |
7.5V | 7.50664 | 7.50666 |
10V | 10.00736 | 10.00736 |
Also of note:
- There are at least two versions of this device: one charged by USB, one is charged by arbitrary 5V input.
- There is a design flaw if you have some kinds of probes: it is possible for your probe inserted into the right side connector to contact two terminals of a chip underneath it, shorting them out. It didn't appear to cause damage, but it still should have been prevented.
What is the usefulness of a battery in a voltage reference? ???
There are at least two versions of this device: one charged by USB, one is charged by arbitrary 5V input.
I think I lucked out. I ordered and received a battery powered AD588BQ voltage reference from China (yeah, I know) Anyway, it came with a supposed readout from a Agilent 34401a. ( whoopy doo a measurement that may or not be calibrated) They showed a measurement of 10.00039 and 5.00057.
Going by the Ad855 Datasheet, It should not be any more than +/- 1mv off of 10v and 5v. I hooked up the +15v and -15v to the board from my power supply (Instek GDP-3303s) and let the AD588BQ and DMM's warmup for two hours and checked the voltages. Meters set to slow mode. Using standard Probemaster 8008 leads 60" long.
unit 1:
AD588 5v: 4.9999v
AD588 10v: 9.9993v
Unit 2:
AD588 5v: 4.9999v
AD588 10v: 9.9990v
I know this is only a relative comparison with nothing verifiable, but even given the GDM-8251 tolerance of .012% +5, I'm pretty happy with it.
edit: I had originaly mistyped the name of the chip as AD855BQ when it is actually a AD588BQ reference chip. Sorry for the confusion it may have caused anyone.
Ambient temperature is important. Make sure that your tests were done at the same temperature before you go trying to adjust any of the multimeters.