Vintage Multimeter: Meratronik U726 (Poland 1976) - Page 1
Forum section: electronics / testgear

author: Thilo78
author_rank: Regular Contributor
timestamp: May 10, 2014, 04:17:27 pm
content: Hey guys,first topic from my side, including a short intro to my person.I'm 35, electrical engineer, and usually working as a project manager in electrical distribution systems for HV and MV grids and industrial infrastructure.As a pasttime, I'm sort of collecting vintage equipment, including my 70s Tektronix 314 scope, my Unigor A43 multimeter and some other things. I use that gear for the second part, working back into digital and analog electronics.My most recent acquisition, which only arrived today, is the Meratronik Electronic Voltmeter U726.According to the sticker, it was built in 1976.Unfortunately, it missed the original power cord. So before powering it up, I had to fix that.I decided to remove the socket on the back and place a nice fabric-clad lead, which is usually applied to electric irons here in Germany. Also I decided to improve an earthing by adding another lead going to the case.Inspired by schwarz-brot's teardown of the RFT 1001.500, I took a few pictures of the inside in the course of the repair.Hope you like the pics.Edit: I did some more research on the specs.Apparently, the U726 is quite a decent meter, capable of adding specific probes (which I unfortunately don't have).As for the regular ranges, it looks like this:DC Voltage 2 mV .. 1000 VDC Current 20 pA .. 100 mAAC Voltage (with probe) 50 mV .. 30 V (20 Hz .. 1200 MHz)AC Current - nope -Resistance 2 Ohms .. 1 GOhmsOne probe seems to be suitable to measure DC voltage up to 50 kV (other than its regular 1000 V DC range).The second is for AC measurements, which the U726 is not capable of on its own.On the good side, the probe allows for measurements up to 1200 MHz (yes, that reads to 1.2 GHz)That AC probe seems to consist of a special heat-treated rectifiying diodetube, that has to be warmed up for 20 minutes before measurement.If anyone knows how that worked, or how to even reproduce that diode probe, I'd be happy to learn.Thilo

author: Thilo78
author_rank: Regular Contributor
timestamp: May 10, 2014, 04:18:09 pm
content: Part 2

author: PedroDaGr8
author_rank: Super Contributor
timestamp: May 10, 2014, 05:25:17 pm
content: Interesting, style appears to be heavily influenced by the old HP instruments that came in that chassis style. With the inlaid side panels and exposed frame on each side.HP 410C volt meterI love the looks of these old beasts. There something very timeless and classic about the look.

author: dannyf
author_rank: Super Contributor
timestamp: May 10, 2014, 06:08:11 pm
content: QuoteNice meter, especially for 1976.QuoteThey all have that styling - Phillips meters for example.

author: wiss
author_rank: Frequent Contributor
timestamp: May 10, 2014, 07:22:51 pm
content: Why would a -76 Polish multimeter have English text? The international language at the time would have been Russian.

author: Bored@Work
author_rank: Super Contributor
timestamp: May 10, 2014, 07:48:52 pm
content: Quote from: wiss on May 10, 2014, 07:22:51 pmBecause they exported stuff to the West, to earn some cold hard cash.

author: kc9qvl
author_rank: Regular Contributor
timestamp: May 10, 2014, 08:27:39 pm
content: The tubehttp://www.radiomuseum.org/tubes/tube_ea52.htmlandhttp://www.tubecollector.org/ea52.htmData sheethttp://www.r-type.org/pdfs/ea52.pdf

author: wiss
author_rank: Frequent Contributor
timestamp: May 10, 2014, 08:35:33 pm
content: Quote from: Bored@Work on May 10, 2014, 07:48:52 pmOk, did they export to BRD? People in DDR did (do) not speak english! If it is an export unit that stayed in Poland/DDR it must be rather rare...

author: Thilo78
author_rank: Regular Contributor
timestamp: May 10, 2014, 08:43:17 pm
content: It is even more interesting:The only documents, that I could find, are from a Hungarian page, that documents Eastern Europe vintage meters.And they are German.Some pictures are labelled Polish, but all the text is German.But te English labels are quite common to the units I looked at.Even the G-1001.500 is externally labelled in English, as far as I remember...I suppose, that the main market for them was the former GDR, as they could hardly import Western Germany's equipment, but rather relied on Polish equipment.Maybe the Russian gear was to different from German standards, but that's just my guesstimation...

author: wiss
author_rank: Frequent Contributor
timestamp: May 10, 2014, 08:52:40 pm
content: Where did you find it?

author: Thilo78
author_rank: Regular Contributor
timestamp: May 10, 2014, 08:56:25 pm
content: Here's the link:http://regimuszereklhanzi.5mp.eu/web.php?a=regimuszereklhanzi&o=Moop90G1nzThe manual comes as individual pages including the schematic in the gallery.I'm going to try and get in touch with the guy for the info on the probes.Just have to figure out that pageEdit: Just occurred to me that you could have meant the meter itself.I found it on eBay, sold by a guy in Berlin (Germany).Either it's inherited or surplus/scrap from a given up company.

author: wiss
author_rank: Frequent Contributor
timestamp: May 10, 2014, 09:50:15 pm
content: yea, I meant the meter.Well, berlin can be either DDR or BRD, so not much of a clue there...

author: Thilo78
author_rank: Regular Contributor
timestamp: March 16, 2016, 07:31:10 pm
content: Hey guys,I finally picked up the topic of the missing AC probe.In the schematics (see previous link), I found a small diagram of the probe.Apparently, it used a Philips or Tesla EA52 signal diode. (First data sheet I found was Philips, but Tesla appears to be more likely)Judging from the Schematic and the data sheet, I suppose it's something like an RF detector circuit with DC blocking, like I found onhttp://www.nonstopsystems.com/radio/frank_radio_antenna_pwr-probe.htmOnly difference: In the Meratronik probe, the diode is reversed, thus producing a negative-shifted voltage (offset is -Upeak)When I'm back home on Friday, I will try to put it together on a breadboard for proof of concept.After that I'd like to try and build the probe at least in the specification ballpark.According to Meratronik, the probe is suitable up to 300 VAC (not specified, if RMS or P-P) with a DC offset of up to 250 V and for frequencies between 20 Hz and 1.2 GHz.(btw: The numbers in my original post appear to be wrong now. Checked the manual again today)Sound pretty interesting, especially for measurements in RF ranges, like bus signals or amplifier circuits.Now my question: How should I calculate the probe circuit, and what requirements would the components (i.e. the capacitor and the diode) have to meet?-------------------------------Data Sheets:Philips EA52:http://www.elenota.pl/datasheet_download/157380/EA52Tesla EA52:https://frank.pocnet.net/sheets/183/e/EA52.pdf

author: freebsd
author_rank: Newbie
timestamp: October 29, 2016, 09:10:14 am
content: Meratronik U726 electronic voltometer:http://jackiewiczowie.blogspot.com/2016/10/meratronik-u726-electronic-voltometer.htmlRemember this: Poland was occupied after World War II until 1993. Only then, September 16, Russian troops moved back to Poland. By this time the Polish managed the Russians. Poland does not have its own army or government. They were Russians.Russian Language in Poland was hated. Brighten after the start of the occupation in 1945 killed hundreds of thousands of Poles. They tortured and buried in mass graves.Poland was occupied by the Russians after the betrayal of February 11, 1945 in Yalta.They sold to the Russians:- US President Franklin Delano Roosevelt- British Prime Minister Winston Churchill.In Poland it did not produce anything with Russian subtitles - unless demanded the Russians. Nothing!Poland produced electronics for other companies, see here multimeter V640:http://tzok.elektroda.eu/