Is this Amprobe AM87 Trms genuine ? - Page 1
Forum section: electronics / testgear

author: sasquatch
author_rank: Contributor
timestamp: July 26, 2015, 03:24:58 am
content: Hi - After the fatal mistake of combining few beers whilst surfing ebay, for some reason I bid on an Amprobe AM87 Trms meter - possibly because I thought the red and grey would contrast nicely next to the usual (copyrighted) yellow and greyAnyway, ignoring the fact that no one else was interested in the meter (alarm bells should have sounded through the beer soaked braincells) for the price of two (more) pints I ended up with this :-http://www.pewa.de/lshop,showdetail,2004g,d,,information.info-artikel.nml,AM87,,Tshowrub--information.info-artikel.nml,.htmI have posted that link because it is pretty much the only information I can find about this meter. That site has a link to the a datasheet that lists other '80 series meters.A search of the Amprobe and beha-amprobe sites shows nothing and the lack of any other info just has me intrigued now, well - either that or i'm rubbish at searching.The external build quality is actually pretty good - the inside - not up to fluke by any means - but it seems to work well enough for a very cheap meter and is certainly accurate enough for general use.Has anyone heard or seen one of these before?

author: retiredcaps
author_rank: Super Contributor
timestamp: July 26, 2015, 05:57:46 am
content: The AM-87, from looking at the datasheet, seems like a very old model back in the 1980s? I say that because the specs of 3200 count, 1.2% + 2 digit for DCV are similar to the Fluke 70 series, HP/Yokogawa era of multimeters.In addition, the input impedance of the AM-87 is 2M ohm, instead of your usual 10M ohm today.Can you post clear focused pictures of the inside? Maybe we can figure out the OEM from the pictures or pcb markings?

author: retiredcaps
author_rank: Super Contributor
timestamp: July 26, 2015, 06:25:12 am
content: BTW, I can't notice but the Amprobe data sheet lists models AM-83, AM-85, AM-87 and AM-88. No doubt, they were copy Fluke's model numbering.

author: miguelvp
author_rank: Super Contributor
timestamp: July 26, 2015, 04:31:47 pm
content: Quote from: retiredcaps on July 26, 2015, 06:25:12 amOr it was just the year they came out? didn't bothered looking up if that's the case.

author: sasquatch
author_rank: Contributor
timestamp: July 26, 2015, 04:56:21 pm
content: Here are some images of the board :-

author: sasquatch
author_rank: Contributor
timestamp: July 26, 2015, 04:57:54 pm
content: :-

author: sasquatch
author_rank: Contributor
timestamp: July 26, 2015, 04:59:04 pm
content: :-

author: sasquatch
author_rank: Contributor
timestamp: July 26, 2015, 05:01:04 pm
content: Having looked again - I certainly wouldn't be testing 600v with this let alone 240v - but hey - for £10 i'm not complaining. It's a cheap meter that works.

author: Wytnucls
author_rank: Super Contributor
timestamp: July 26, 2015, 05:09:18 pm
content: Probably made by Appa in Taiwan. The top board has the HT Italia marking. (HT85/87)Samsung DMM ADC and AD736 RMS converter.

author: Zero999
author_rank: Super Contributor
timestamp: July 26, 2015, 05:29:54 pm
content: I've used the AD736 before. It's a good IC.http://www.analog.com/media/en/technical-documentation/data-sheets/AD736.pdfThere appears to be a crack in the bridge rectifier, near the input jacks or is it just a piece of hair or thread?

author: sasquatch
author_rank: Contributor
timestamp: July 26, 2015, 07:32:44 pm
content: The rectifier is fine - it's just a marking on the chip surface (probably from a screwdriver) made when someone has removed the fuse.

author: sasquatch
author_rank: Contributor
timestamp: July 26, 2015, 07:36:00 pm
content: Quote from: Wytnucls on July 26, 2015, 05:09:18 pmThanks for this - even the case is the same - just red (we all know how important colours are on a multimeter

author: retiredcaps
author_rank: Super Contributor
timestamp: July 28, 2015, 06:42:54 am
content: Quote from: Wytnucls on July 26, 2015, 05:09:18 pmThat is my guess as well, but I can't find anything in the APPA website to confirm. Maybe the age of the meter pre-dated APPA's website?QuoteLooking at the current HT handheld multimeter lineup, it is clear they just rebadge other people's products including APPA (meters with the overhang rotary knob), CEM Instruments (tall exaggerated LCD digits), Brymen (HT-603) and even Gossen (HT-410)!!http://www.ht-instruments.com/en/products-ht/digital_trms_multimeters/family-result?fami=MULTIMETRI

author: retiredcaps
author_rank: Super Contributor
timestamp: July 28, 2015, 06:45:51 am
content: Quote from: sasquatch on July 26, 2015, 05:01:04 pmI think I would have bought it too for that price. Thanks for sharing the pictures. Certainly, not a whole lot of information on the Internet on this model.After you use it for a while, it would be interesting to hear your feedback on its performance.

author: macboy
author_rank: Super Contributor
timestamp: July 28, 2015, 01:18:06 pm
content: Quote from: retiredcaps on July 28, 2015, 06:45:51 amI would have as well. This is true True RMS meter, given the presence of the AD736 RMS converter. Actually, the bare AD736 alone, in single quantity from Digikey, would have cost as much as what was paid for the meter.

author: Wytnucls
author_rank: Super Contributor
timestamp: July 28, 2015, 01:34:47 pm
content: Here is a new HT88 in Singapore for 24 quid:http://singapore.locanto.sg/ID_476214030/ITALIA-HT88-MULTIMETER.html