BK Precision 2712 DMM - Page 1
Forum section: electronics / general

author: carloscuev
author_rank: Regular Contributor
timestamp: June 08, 2011, 05:10:33 am
content: Hello, I bought this DMM, which looked one step further from the 2709B that Dave reviewed, it is different in many aspects, pics speak for themselves:Front:I prefer Rel button than Hold button, the continuity tester is not as fast as 2709B.If you are looking to buy this and have a question about the meter please PM me.

author: EEVblog
author_rank: Unknown
timestamp: June 08, 2011, 10:09:20 am
content: Nice photos, thanks for sharing.The choice of Hold function instead of Rel is a big fail IMO.The Extech EX320 has the same thing, that they swapped on the 330.Dave.

author: House91320
author_rank: Regular Contributor
timestamp: June 08, 2011, 10:13:10 pm
content: i think it has a 555 timer in there

author: carloscuev
author_rank: Regular Contributor
timestamp: June 25, 2011, 08:29:53 am
content: Quote from: EEVblog on June 08, 2011, 10:09:20 amI agree, completely.

author: ejeffrey
author_rank: Super Contributor
timestamp: June 25, 2011, 09:08:14 am
content: Quote from: EEVblog on June 08, 2011, 10:09:20 amThis is an especially weird choice specifically for a high resolution 40000 count meter where you are more likely to want to zero out a background reading! Makes no sense.

author: carloscuev
author_rank: Regular Contributor
timestamp: November 06, 2012, 05:23:33 am
content: Here's the calibration manual provided by BK for this multimeter, sadly I don't have everything needed to calibrate all rangesmight be useful to somebody else !

author: sorenkir
author_rank: Regular Contributor
timestamp: June 06, 2019, 02:29:15 pm
content: Bought one, used but as new, a few days ago (for 30 euros delivered, I should post in 'scores' thread!).Here is a photo of the PCB:Cyrustek ES51997 (60000 count ADC, but the meter is "only" 40000 counts!?)Synctec STM1105 (could not find any data on this microcontroller chip)Two trimming potentiometers, but they are not described in the calibration procedure!Input protection and build quality are very good.Michel.

author: David Hess
author_rank: Super Contributor
timestamp: June 06, 2019, 08:12:10 pm
content: Meters like this are on my short list of candidates because of their superior terminal arrangement.Unfortunately the 2712 like most autoranging meters has variable input resistance. None of the B&K meters with 10 Megohm inputs are more than 3-1/2 digits.

author: bdunham7
author_rank: Super Contributor
timestamp: June 06, 2019, 10:00:51 pm
content: Quote from: David Hess on June 06, 2019, 08:12:10 pmMy BK 391A (manual ranging) is 20000 count and 10M on all ranges and it gets pulled out most often for that specific reason. Most people looking for a low-priced hand held DMM probably don't care, but obviously voltage dividers and HV probes do!

author: David Hess
author_rank: Super Contributor
timestamp: June 07, 2019, 03:54:00 am
content: Quote from: bdunham7 on June 06, 2019, 10:00:51 pmThe 391A is not on my short list because it uses the inferior linear terminal arrangement. When I finally buy a new meter, I may have to just live with that but it opens up lots of options.Right now the best candidates I know of are the Amprobe 37XR-A and 38XR-A. They are better than my Beckman RMS225 which I like so much but not better than my Tektronix DMM916 (Fluke 87 clone) except in terminal arrangement. They are autoranging meters however so I am somewhat dubious of their claims of 10 megohm input resistance. It is something I need to verify.

author: bdunham7
author_rank: Super Contributor
timestamp: June 07, 2019, 03:53:37 pm
content: Quote from: David Hess on June 07, 2019, 03:54:00 amI try not to be too picky because it is easier to get bargains that way. I only like BK stuff if and when I can get it cheap--I paid $69 for my 391A NOS/NIB. Why do you dislike the linear terminal arrangement? I've never had a meter any other way but I don't see what the advantage would be.

author: David Hess
author_rank: Super Contributor
timestamp: June 08, 2019, 04:54:42 am
content: Quote from: bdunham7 on June 07, 2019, 03:53:37 pmMy current meters still work fine and are just getting old so I can be picky.QuoteThe "star" terminal arrangement with common in the center allows the use of standard 3/4" banana plugs for all inputs. On my DMM916 with its linear terminal arrangement, I cannot use a 3/4" banana plug in 10 amp mode which is really annoying.

author: Ordinaryman1971
author_rank: Frequent Contributor
timestamp: June 10, 2019, 03:42:21 pm
content: BK meters are really nice, the only thing that bothers me a bit is a beeping sound they make when they about to turn off in auto mode, and the sound they make when switching ranges....I have 393... not sure if anybody has any experience with this one. I think that is the highest model for the handheld.Feels solid, like the design... expensive though.

author: jfiresto
author_rank: Frequent Contributor
timestamp: June 11, 2019, 06:01:10 am
content: I have a B&K 390A, the model below the 393, which is also quite nice. Instead of true-RMS AC, it provides peak reading of voltage and current pulses. Both meters have data logging which I find works well. I have written a command line python utility to capture the data from mine. Its help text suggests the logging's scope:QuoteFor completeness, here is the inside of a 390A:

author: David Hess
author_rank: Super Contributor
timestamp: June 11, 2019, 07:15:29 pm
content: Quote from: jfiresto on June 11, 2019, 06:01:10 amI would not mind finding a handheld meter which can read the actual peaks with a solid specification but all of the ones I have tested are slow and have vague specifications. I have pretty much given up on this.

author: jfiresto
author_rank: Frequent Contributor
timestamp: June 11, 2019, 09:16:56 pm
content: Quote from: David Hess on June 11, 2019, 07:15:29 pmHere are the specs for the ES51962 DMM chip used in the B&K 390A:

author: shakalnokturn
author_rank: Super Contributor
timestamp: June 13, 2019, 11:27:38 pm
content: Mine arrived from the same source as Sorenkir's. Looks like new too, I'll have to check it against a better meter for calibration though.A few impressions on the thing...Cute little DMM with a size that fits the hand really well.The rotary selector has a nice feel, would have been nicer to handle if the pointing end had been a little higher.The magnet is convenient andjust aboutenough to hold the meter in place, a little stronger would have been better. The iron washer in the tilt stand to keep the magnet stuck to the back of the meter is a fail, just not big enough.The tilt stand has a good angle but feels flimsy, a hand strap would have been nice.Overall build quality is towards the minimum, 3 screws to hold the shell together, some torsion on it and you hear the two halves squeaking at each other.LCD display is very readable although not the best I've seen for viewing sideways, the backlight is good.It really is a pity for the "Hold" key not being a "Relative" one, any chance of correcting that by unused connections on the PCB?The PCB layout is more than neat enough to my likings, without looking into routing criticisms.It seems that BK precision sell rebranded Chung Instrument (CIE) meters, a couple of decades ago I may have hesitated who rebranded who, not any more.Equivalent to the BK 2712 model is the CIE-3140B top of the family, there is also a CIE-3130B model with 22k counts and a "Relative" key rather than "Hold"...The 22k count 3130B has better DCV accuracy than the 40k count 3140B. How much sense does that make?

author: shakalnokturn
author_rank: Super Contributor
timestamp: July 05, 2019, 02:54:48 pm
content: I got hold of a older BK 2712 that funnily has quite different innards, uses a different ADC and MPU. The MPU confirms that CIE is the manufacturer, it has their name on it...I went looking for a way to add or modify the "hold" key into a "relative" key on both models, it doesn't look possible.

author: David Hess
author_rank: Super Contributor
timestamp: July 05, 2019, 11:44:58 pm
content: I wish BK made a higher performance version of their manual ranging meters. They are all stuck at 3-1/2 digits.