Questions on 34401 Calibration - Page 1
Forum section: electronics / testgear

author: Vgkid
author_rank: Super Contributor
timestamp: November 04, 2014, 02:55:33 am
content: I received a working but really out of calibration 34401. Original calibration date is in 2002, the cal count is 97., revision 10-05-02. I hooked it up to Dougs Voltage standard, VREF10-003, and it displays 9.982X volts really stable day to day though the last digit bobbles up and down by 1 every few seconds. I dont have a stable ac source to test, but the front/back 2/4 wire ohms are rather stable. so will getting this unit calibrated solve this, or should I start troubleshooting.// end rant, info dumpforgot passes self tests.

author: Vgkid
author_rank: Super Contributor
timestamp: November 19, 2014, 02:50:01 am
content: Quick update:I checked my 34401a against a relatively calibrated 3456a(2012) and it is a few counts off at 10v when comparing them. So that means that the Dougs Vref must not have survived shipping, or else there is a bad solder joint on the trimmer resistor.

author: jpb
author_rank: Super Contributor
timestamp: January 22, 2015, 06:59:04 pm
content: Quote from: Vgkid on November 19, 2014, 02:50:01 amIt has been a while since I've been on Doug's site and I just returned today to see that he has the new VREF10-003 at what seems a very reasonable price. Since it's purpose is to be a voltage transfer I was slightly disturbed to read your post.Have you since got to the bottom of the issue? What was Doug's response when you raised it with him?

author: Vgkid
author_rank: Super Contributor
timestamp: January 22, 2015, 08:46:34 pm
content: I never did actually get back to him...It worked correctly originally, but I think it might have been dropped (not by me, but who??). So that must have messed up the trim pot(possible bad solder joint/ or the pot did not like that drop). But has been stable.

author: jpb
author_rank: Super Contributor
timestamp: January 22, 2015, 10:08:13 pm
content: Quote from: Vgkid on January 22, 2015, 08:46:34 pmThanks for clarifying things.

author: Vgkid
author_rank: Super Contributor
timestamp: January 23, 2015, 01:45:35 am
content: The only other issue i had with it is the unit failled to power on about a month after purchase. The power switch stopped working for a while.

author: metasequoia
author_rank: Newbie
timestamp: January 23, 2015, 02:36:32 am
content: Hello, this is Doug from voltagestandard.com. Please send me your voltage reference- if you will pay the postage both ways I will repair/recalibrate as necessary no charge. I suppose it is possible that a drop could cause such a voltage shift, but I doubt it. I think a more likely cause would be static electric damage. There are internal trim fuses inside the LT1021 package that can be opened up by static electricity- I know because I got careless on a couple of test units and blew them out and the output voltage shifted about 10mV which is a HUGE amount- similar to what you are experiencing. Please don't hesitate to contact me if you have problems with anything I have sold! From the forum post I don't know who you are or else I would have contacted you privately....Regards,Doug Malone

author: Vgkid
author_rank: Super Contributor
timestamp: January 23, 2015, 07:00:49 pm
content: Mr. Malone, it might be a while before I mail it out, I will email/PB you when I do.having some fun with the 3456a. * temps varied +/- 2degC from 17Ctaken over 11 hours, 100NPLC, AC filter on9486 readingsVariance: 1.403606E-9lower: 9.98224upper:9.98245mean:9.98236