Dual impedance multimeter recommendations? - Page 1
Forum section: electronics / testgear

author: rauldm
author_rank: Regular Contributor
timestamp: July 27, 2019, 02:04:14 am
content: I need a meter with LoZ impedance, I have the 289, but I need another, my options are the Fluke 117 or GreenLee DM-830A. I know the greenlee is a brymen. I have another amprobe and keysigth meters, but the performance is not sorprendent like the my Flukes. For example my U1282A, the bar graph when I work with Ohms is more slow than my Flukes, the bar graph performance in the u1282a only detects clicks on 40 Hz update mode. My Fluke 87V even on hi-res mode the bar graph is fast. Really brymen meters are fast? the money difference between Fluke 117 and DM-830A is not important, but DM-830A it has a interesting LoZ mode, for example, the LoZ for Fluke is 3 kOhms, for keysight is 2 kOhms up to 600 V for both, the brymen change the input impedance from 3 kOhms to 460 kOhms for 1000 V, sounds good but, is functional? the brymen responce is really more fast to Fluke 117? Regards.

author: MarkF
author_rank: Super Contributor
timestamp: July 27, 2019, 02:33:18 am
content: +1 for the Fluke 117.I have both a Fluke 117 and a Fluke 87V. As far as the bar graph and other responsiveness, both Flukes are about the same.Since you have a 87V, you can expect the Fluke 117 to be similar to the 87V as a comparison.

author: rauldm
author_rank: Regular Contributor
timestamp: July 27, 2019, 02:51:31 am
content: Are you using the LoZ mode in your 117? I had a good experience with this function in my 289. Therefore I need another meter with this function, is essential on electrical installations. You can solve some problems on control area with this feature.

author: MarkF
author_rank: Super Contributor
timestamp: July 27, 2019, 03:32:38 am
content: I rarely use the LoZ mode.However, I did just use it this week repairing a stove.The 117 was showing a low AC voltage on normal AC V range with stove unplugged.Switching to LoZ, it measured 0 VAC as expected.

author: MarkF
author_rank: Super Contributor
timestamp: July 27, 2019, 04:07:02 am
content: And, if you want to see inside:

author: Fungus
author_rank: Super Contributor
timestamp: July 27, 2019, 10:05:50 am
content: Quote from: rauldm on July 27, 2019, 02:04:14 amYes.

author: L_Euler
author_rank: Regular Contributor
timestamp: July 27, 2019, 11:45:30 am
content: Before i got a 289 I built a small adaptor box that was inserted between the probes and meter with a couple switchable resistors. (1000ohm, none, 10000ohm) and appropriate fusing for the resistor sizes. It worked beautifully and was able to use with any multimeter. I was checking a lot of PLC solid state outputs in industrial control systems.

author: rauldm
author_rank: Regular Contributor
timestamp: July 27, 2019, 09:02:57 pm
content: Someone tested Auto-check on Brymen multimeters?

author: Per Hansson
author_rank: Unknown
timestamp: July 27, 2019, 09:28:59 pm
content: Quote from: L_Euler on July 27, 2019, 11:45:30 amFluke does sell such an adapter, I use it myself and it works fine.Of course it would be surprising if a resistor in a plastic box did not work wellhttps://www.fluke.com/en-us/product/accessories/adapters/fluke-sv225

author: Electro Detective
author_rank: Super Contributor
timestamp: July 28, 2019, 12:00:09 am
content: If you don't need the features and price of the 117, I can vouch the 114 does a good enough job in Low-Z as the 289.The 114 is my go to 'idiot' meter, it has no current inputs or fuses to think aboutand good enough for quickie troubleshootsThey go cheap used, people sell them off to upgrade to feature filled 117, 87V, Brymen, Keysights, etcand miss the point of a simple meter with the basics Low-Z, AC, DC, Min Max, Ohms/Buzzerand according to Mr. Smith's exhaustive tests, a fair 'resistance' to ESD styled -BANGS!-fwiw I can be 'less careful' with using both the 114 and non Low-Z 101, flanked by two clamp meters,gloves, glasses, rubber boots, diligence...and so far they've kept my pocket healthyFYI for battlers that just want an entry level 'LOW-Z' capable meter that's affordable, and worked well for me before the Flukes rocked up, the Klein CL3200 won't break the bank,and came with a nice zippered pouch, great leads and croc/alli adapters.Still have it, doing tool box #3 duty nowadays

author: rauldm
author_rank: Regular Contributor
timestamp: July 28, 2019, 02:53:08 am
content: Really this adapter is good option for me, I can put in every meters, thanks for the answer. I think with the price this adapter and the 117 I would buy the Brymen, but I have more Fluke products and accesorys.

author: rauldm
author_rank: Regular Contributor
timestamp: July 28, 2019, 02:57:27 am
content: In my country for some reason, the Fluke 117 is more popular than Fluke 114, I can find for the same price even new. Thanks for your answer.

author: Electro Detective
author_rank: Super Contributor
timestamp: July 28, 2019, 10:53:52 am
content: The Fluke Low-Z adapter was expensivefor a 3k resistorso I just bought a new Klein CL3200 and a used 114 for the same'boutique 3K resistor'moneyDIY adapter was an option too, so was lazinessBesides, I'd rather have the CAT ratings intact with a purpose built and rated Low-Z meter, rather than have addonsfwiw be careful as Low-Z mode can sometimes bring on BANGS!and guaranteed RCD/GFCI trips

author: Neomys Sapiens
author_rank: Super Contributor
timestamp: July 29, 2019, 05:00:30 pm
content: If you consider buying used, there is also the Metrahit12/14 from GMC (look for a thread named 'show your multimeter', there you can see mine.)Also, some of the newer GMC multimeters have such a feature.

author: Electro Detective
author_rank: Super Contributor
timestamp: August 02, 2019, 11:03:45 pm
content: FWIW: Here's cool brief PDF info sheet from Fluke that sold me to get a Low-Z 'Ghost Buster' meter(or two..)Dual impedance digital multimeters— What's the point?support.fluke.com/find-sales/Download/Asset/2718074_6116_ENG_A_W.PDF

author: SG-1
author_rank: Regular Contributor
timestamp: August 03, 2019, 12:35:33 am
content: Fluke also offers the SV225,but you can buy an off brand meter for the same price.

author: Electro Detective
author_rank: Super Contributor
timestamp: August 06, 2019, 09:30:08 am
content: For the money Fluke charge on long runningmoney for jamflagship meters,the encased boutique 3000 ohm resistor should be chucked in as a freebie

author: 001
author_rank: Super Contributor
timestamp: August 06, 2019, 10:32:49 am
content: Can anybody told me why 3kOhm Fluke addon rated to 1000V?http://assets.fluke.com/manuals/sv225___iseng0000.pdfIt is only resistor, isnt`it? And by Ohm law it must be heated with 333watts

author: 2N3055
author_rank: Super Contributor
timestamp: August 06, 2019, 03:16:19 pm
content: Quote from: 001 on August 06, 2019, 10:32:49 amIt is not a resistor.It is a PTC, that heats up and increases resistance in few milliseconds... So current drops considerably...

author: 001
author_rank: Super Contributor
timestamp: August 06, 2019, 05:41:47 pm
content: Quote from: 2N3055 on August 06, 2019, 03:16:19 pmThanx a lot!But why 3kOhm? 3kOhm at what voltage?How to clone it properly? Is simple 10kOhm resistor will work same way at 0-30V?

author: Neomys Sapiens
author_rank: Super Contributor
timestamp: August 06, 2019, 11:10:05 pm
content: Quote from: Electro Detective on July 28, 2019, 10:53:52 amIf the Fluke adaptor in question is the 'stray voltage test leads' that came with the original 27 (AN/PSM-45A), it was not a resistor, but a PTC thermistor.

author: Electro Detective
author_rank: Super Contributor
timestamp: August 06, 2019, 11:45:33 pm
content: Quote from: 2N3055 on August 06, 2019, 03:16:19 pmSo is that what they also use in the 114 to 117 series and Fluke 289?IIRC they show up as 3K when tested with another meter's resistance range (in lazy Auto mode)Does a PTC register as 3K instantly, or sort of ramps up to that value once the heat is on? ()Why not a monster 3K resistor with heatsink and one of those orange current protection thingies, rattling around in a fuglee box with sockets and flying leadsAnyone got one of theseboutiqueyblack box Fluke SV225and a knack for cracking it open without trashing it?

author: rauldm
author_rank: Regular Contributor
timestamp: August 07, 2019, 01:19:33 am
content: Hi, I bought a new Fluke 117, I tested with AC and DC voltage on LoZ mode, the input impedance change with increment of voltage, for example I tested with 133.8 Vac, neglecting capacitive or inductive effects, I have around 15.7 kOhm, input impedance, with 20 Vdc I have around 3.3 kOhms, is not single resistor. With suggest from Per Hansson, I researched about SV225, on youtube exists a tutorial for repair this unit, and shows a resistor and PTC. Thanks for contributions, I hope buy SV225 too.

author: rauldm
author_rank: Regular Contributor
timestamp: August 07, 2019, 01:37:23 am
content: The ghost voltage is common on electrical control installations, some weeks ago, I was repairing a control system with contactors and power electronics, I was with 289 and 376 fc, high impdeance mode on 289 and 376 fc show voltage, I remmenber the LoZ mode on 289 and surprise, is not real tension, the meters only show coupled voltage for capacitive efect on the control lines near power lines.The motive for this post was I would want have at least other meter with this feature, I bought the 117 yesterday, but I want have Lo Z on my others meters. Thanks for SV225 suggest.

author: HKJ
author_rank: Super Contributor
timestamp: August 07, 2019, 04:55:52 am
content: A typical LowZ PTC impedance curve:This curve is from a Fluke289, but other meters are similar.

author: 2N3055
author_rank: Super Contributor
timestamp: August 07, 2019, 07:03:52 am
content: Circuit uses same PTC as for protection, one or few of them , with surge rated resistor in series, to limit initial current and to have current limit in case something goes wrong with PTC .It starts at 3 kOhm (I presume Fluke one will have 1.1k PTC and 2.2k surge rated resistor in series) when cold (25°C) and then resistance of PTC goes up in megaohm range when heated. So much lower current later.P.S. Found the mentioned video, Fluke probably uses two 1.1 K PTC (like the YS4020) and one 1k surge resistant resistor in series.

author: HKJ
author_rank: Super Contributor
timestamp: August 07, 2019, 07:10:59 am
content: Quote from: 2N3055 on August 07, 2019, 07:03:52 amNot really, as you can see on my curve above. Typically a bit above 1 Watt is needed to keep the PTC heated, this means at around 1000V it might just reach 1Mohm.

author: 2N3055
author_rank: Super Contributor
timestamp: August 07, 2019, 07:37:59 am
content: Quote from: HKJ on August 07, 2019, 07:10:59 amThat is what I said.It reaches order of magnitude of megaohms when heated. I wasn't talking about voltage coefficient..In Fluke adaptor they use two in series, so heating will be divided between the two of them.How did you measure that curve? Did you sweep the voltage in one go, or did you measure current at voltage points one by one, letting it cool down for few minutes. If you did a sweep, did you wait at discrete points for it to reach thermal equilibrium? It would be interesting to know the method.Also what would be interesting is to record current with a scope on connect to see how it draws larger current in the beginning, and how that curve is different at different voltages......

author: HKJ
author_rank: Super Contributor
timestamp: August 07, 2019, 08:42:15 am
content: Quote from: 2N3055 on August 07, 2019, 07:37:59 am100kOhm at 250V is hardly in the megaohms magnitude.Quote from: 2N3055 on August 07, 2019, 07:37:59 amI sweep the voltage measuring in 1V steps from 10 to 250V, each point takes 1 second, i.e. a total of 4 minutes for the test.

author: Electro Detective
author_rank: Super Contributor
timestamp: August 07, 2019, 10:15:36 am
content: youtube.com/watch?v=IOoJmMBE5D8The not impressed Youtuber paid 80 bucks (US?) for a boutique 3K resistor and PTC (50 cent total?) in a plastic box,that appears to have beenspitsolderedwith lashings of planned obsolescenceand assembled at ThreeHungLow Industrieswith perhaps a QC(Questionable Crap)stickerslapped on by ailing wheelchair bound honorable great great grandad gathering peanuts for the grandkids to go to school and or eatJust how much percentage are the shareholders demanding, or the brokers that stitched up their life savings promising nowadays?I don't even want to think how much this toy costs today in Kangaroo Land,I bought an unloved unused 114 and NEW Klein meter (both with Low-Z) for the same price a while back,as one of these overpriced Low-Z interfaces, stashed inside a repurposed USB charger housing.You could chain solder the 3 components, put the lot in a clear zip lunch bag with flying leads,save a bundle,inspection and servicing would be a breeze

author: 2N3055
author_rank: Super Contributor
timestamp: August 07, 2019, 10:38:38 am
content: Quote from: HKJ on August 07, 2019, 08:42:15 amThank you for details.FYI looking at the datasheet for a Vishay PTC and it is 1 Meg at 135C and 10 Meg at 150C. It is 100k at cca 130C. Slope is very steep at that point, ambient temp will have large influence together with thermal design.Regards..

author: 001
author_rank: Super Contributor
timestamp: August 07, 2019, 12:10:48 pm
content: Quote from: Electro Detective on August 07, 2019, 10:15:36 amThanx a lotColor code at 2:17 says resistor is only 17 Ohm? (I can be confused with my monitor color and eyes) What real values of two PTCs and resistor are?

author: Shock
author_rank: Super Contributor
timestamp: August 07, 2019, 01:28:03 pm
content: Been already discussed in this other thread, I read the value as 1K which makes sense, it looks like brown black red gold red in the video.https://www.eevblog.com/forum/testgear/brymen-bm867-bm869/Looking inside the Fluke 117 confirms the resistor and PTCs are there.

author: Per Hansson
author_rank: Unknown
timestamp: August 07, 2019, 07:52:03 pm
content: Quote from: Electro Detective on August 07, 2019, 10:15:36 amI agree with your post, the price is just silly, for me I use it for work.But I also just want to highly underline that there is another side to this, safety:The Adapter is specified for CAT III 1000V/CAT IV 600V per EN61010.I use my SV225 for a secondary purpose: to discharge capacitors in servos, as can be seen in the curve above it's not the best, but so far it has been useful to me.Now imagine what would happen with an adapter actually assembled at ThreeHungLow Industries as you say.Here I will give an idea:https://youtu.be/OEoazQ1zuUM?t=345Just something to keep in mind when measuring high energy circuits which is the whole idea if you need this adapter in the first place.I agree that buying a meter with LoZ mode is better, be careful though: I thought my Fluke 28-II had such a mode but it's a low pass filter, not low impedance!

author: 001
author_rank: Super Contributor
timestamp: August 07, 2019, 07:59:02 pm
content: Quote from: Shock on August 07, 2019, 01:28:03 pmThank You!I google for PTCs but most of them have limited work cycles about 100 onlyWhat PTCs are used by FLUKE?

author: Electro Detective
author_rank: Super Contributor
timestamp: August 07, 2019, 10:05:55 pm
content: Quote from: Per Hansson on August 07, 2019, 07:52:03 pmTBH I would rather have the resistor and PTC inside a CAT rated meter housing, that I can physically check on,rather than a glued up re-purposed USB box with a CAT rating,that may have been soldered together and gooped up by a friday afternoon pub crawling assemblerand yes, I use the Low-Z mode for poor mans discharging duties as well, and may wait a while...Still a better bet than dealing with surprise zapsEDIT:Zap City>youtube.com/watch?v=oahQRSRx_38Every New Yorker should be issued with a Low-Z accessory and app for their phones

author: rauldm
author_rank: Regular Contributor
timestamp: September 08, 2019, 04:30:35 am
content: Quote from: Neomys Sapiens on July 29, 2019, 05:00:30 pmReally I didn't know nothing Metrawatt meters, I impressed with the price, normally all brands it has a high-end models to same price, Metrawatt is really expensive even with same specs, also I impressed with high-end are very especialized, for example the CAT rating is to low but 6.5 digits in a portable device is amazing. I think this meters play on other scale of market. I have Fluke 289, 28II, 87V and 117, also keysight U1282A and Amprobe 37XR-A.

author: BB3553AM
author_rank: Contributor
timestamp: April 14, 2020, 05:47:16 pm
content: Dear HKJ,my sincere thanks and congratulations on your website :https://lygte-info.dk/review/DMMBrymen%20BM869s%20UK.htmlI just bought a BM869s and a AN870 based on your reviews.( I have a question about the AN870, but let's not pollute this thread)regarding the PTC that were observed, are we able to identify the part number ?I plan to do my own low impedance "network" for lowZ measurement , we can see indeed to 2 PTC on either side and a power resistor in the middle of those in this videoabout the sv225.Thanks for help.

author: BB3553AM
author_rank: Contributor
timestamp: April 14, 2020, 09:05:20 pm
content: Maybe this (family of) device could do the job ?https://www.vishay.com/docs/29072/ptccl.pdf

author: Per Hansson
author_rank: Unknown
timestamp: April 15, 2020, 04:15:39 pm
content: Not sure about the part number for the PTC.But it would make sense that they reuse the same PTC as in their meters?Check out some schematics for Fluke DMM's, some do exist for their slightly older models...

author: BB3553AM
author_rank: Contributor
timestamp: April 15, 2020, 08:20:23 pm
content: Thanks for your contribution.I think the C885 from epcos (now tdk) should be a good match :https://www.mouser.com/datasheet/2/136/OC_B59884_B59885_B59886-62199.pdfBy using 2 of them plus a 4w resistor of 1KOhm, we could achieve something very close to the sv225.

author: Shock
author_rank: Super Contributor
timestamp: April 15, 2020, 11:16:01 pm
content: I checked a couple of Fluke service manuals with parts listings and got 1.1k 20% tolerance for the PTCs. Part numbers were YS3961 and 911P67E112MW07.What about B59774C0115A070 it's 1.1k.I get the feeling Fluke has special order part dimensions for their MOVs and PTCs so if they are ever going into a multimeter check that first. I suspect they are probably manually sorted as well as 3.6K is a bit out there.

author: BB3553AM
author_rank: Contributor
timestamp: April 16, 2020, 10:45:42 am
content: Thank you Shock for the information. Much appreciated.Indeed, the B59774C0115A070 is also a very good option.