DMMCheck Plus - Page 1
Forum section: electronics / testgear

author: rkeller
author_rank: Contributor
timestamp: September 16, 2023, 06:23:54 pm
content: Introduction:Hi I’m Russ with DMMCheck PLus. Thanks to everyone for your postings. I really appreciate the feedback, critiques, suggestions and criticisms along with the kudos. I purchased the DMMCheck Plus line from Doug Malone (engineers engineer) after they had become unavailable. My main business has several products with UL and ETL listings and the inspectors want to see traceability and current calibrations, which meant sending out expensive test equipment only to have it trashed in shipping. Doug’s DMMCheck Plus with its traceability would satisfy these requirements but Doug was thinking about retirement and dropping the line. The more I listened to Doug the more he reminded me of the truly brilliant electrical engineers I worked with at Trimble Navigation back in the 90s and early 2000s. We negotiated a deal I acquired the necessary test equipment and video taped Doug in his cal lab in WA to duplicate that here in NC.Doug and I noticed some customers also wanted to be able to test the Inductance and Capacitance functions on their multimeters so he designed and we built a daughter board for the unit with the LC components. Our main goals were to be able to provide a cost effective solution to the problem of in house calibrations and functionality testing for DMMs. Although we sell to everyone from Avionics shops, Tesla, NASA, and Railroads to the National Zoo, most of our customers are like Chris W4CEC, an engineer who likes to experiment with electronics, and Amateur Radio. We also service Dougs original customers with repairs and recalibrations.Speaking of recalibrations. Some have suggested we show the before and after measurements. We have tossed this idea about several times and keeping with the goal of providing a low cost reference AND low cost recalibrations (still $20 or free within the first two years), we opted to not go with the unnecessary step (in most cases) of a pre and post calibration since the only value that really changes is the DC voltage. The people who inspect our test procedures and equipment for ETL and UL don’t care about pre-calibration numbers so we thought this was a non issue but perhaps not. If anyone thinks this is necessary or they would like to see it, even for curiosity sake, please chime in and let me know. I would be happy to add a check box to the website for those who would like the pre/post numbers.Thank you again for all your comments, good, bad or otherwise, it’s always better to practice with someone better than yourself if you want to improve. Looking forward to serving as best as we are able.Doug and I are still collaborating and looking forward to introducing something new and improved this year, stay tuned…Kind Regards,RussKB4RK7 3 and for the low power folks 7 2…

author: bdunham7
author_rank: Super Contributor
timestamp: September 16, 2023, 06:36:18 pm
content: Every calibration lab service and procedure I've seen will at least notify you if our instrument was out of tolerance (perhaps designated something like Z540.x w/ OOT) when you shipped it in. If it was OOT at the end of the calibration period, than that is a failure and all of your previous work since the last calibration is now suspect. Of course there are always additional charges for actual data and uncertainties and nobody is calibrating anything for $20. So perhaps offer it for an extra fee?Are you saying that UL and ETL do not require or even prefer instruments to be calibrated in an accredited lab?

author: rkeller
author_rank: Contributor
timestamp: September 16, 2023, 07:42:55 pm
content: I'll take that as a vote for the pre and post cal option.

author: J-R
author_rank: Super Contributor
timestamp: September 16, 2023, 07:50:45 pm
content: Always nice to have a thread started by a product manufacturer! I'm sure there will be plenty to discuss.The as-received value for the DC voltage allows you to be able to see the drift, good and bad. The leads would already be connected in preparation for tweaking the trim pot. Doug does provide this value with his references. To clarify: current, AC voltage and frequencies are set when assembled and are not adjustable? And of course there is no such thing as a pre-cal measurement for the passives.The question about the planned reference upgrades was brought up in another thread, any news to share on that?

author: mendip_discovery
author_rank: Super Contributor
timestamp: September 16, 2023, 08:03:39 pm
content: Welcome to the Hotel Cal...err. Forum.Before and after adjustment readings can be handy to see if there is drift and how much better than the specs it is.Keep up the good work.

author: Veteran68
author_rank: Frequent Contributor
timestamp: September 17, 2023, 12:59:29 am
content: Hi Russ, glad to see you officially representing DMMCheck Plus on the forum now! Also glad to hear you still collaborate with Doug.I ordered a v6 a couple weeks ago when orders opened up, and messaged you with some questions to which you responded promptly. Thanks for that! Looking forward to my v6 arriving soon as I hope the 250hr burn-in cycle should be completing.I am also in the camp of preferring to have before & after calibration/adjustment values.

author: rkeller
author_rank: Contributor
timestamp: September 17, 2023, 01:44:57 am
content: Noted, another vote for the requested pre/post.Thank you again.