What is a good price for a used TM502A + AM503B + A6302.  - Page 1
Forum section: electronics / general

author: trevwhite
author_rank: Frequent Contributor
timestamp: January 02, 2016, 02:30:45 pm
content: I am after a current probe and my budget isnt great. It seems the AM503B and maybe a A6302 is a good combination.What do people feel is a good price?I am in the UKTrev

author: HighVoltage
author_rank: Super Contributor
timestamp: January 02, 2016, 02:54:03 pm
content: What current ranges and frequencies (DC, AC) you need?There are plenty of alternatives with much lower prices.I bought a few AEMC DC / AC current probes for around Euro 150

author: trevwhite
author_rank: Frequent Contributor
timestamp: January 02, 2016, 03:12:02 pm
content: Well I want it for some switch mode stuff and I wasnt sure I needed more than 20amps. After that 50Mhz seemed good bandwith.Do you have specs and model number please?

author: HighVoltage
author_rank: Super Contributor
timestamp: January 02, 2016, 04:08:52 pm
content: This one for instancehttp://www.ebay.com/itm/AEMC-SL261-AC-DC-Current-Probe-100mA-to-100A-10A-100mV-A-100A-10mV-A-Output-/151930310233?hash=item235fc08e59:g:v4MAAOSwHQ9WZMZ2AEMC SL261It is made by AEMC but also sold under Fluke, Agilent, Tektronix branding.The AMEC is usually the lowest price and the Fluke the highestFrom their website:SL261 Oscilloscopes & BNC Terminated ProbesThe Model SL261 is a portable 100A peak current probe with insulated BNC output cable that can accurately measure AC or DC current waveforms. The unit has proportional mV output for direct readings on oscilloscopes. Three position slide switch on handle selects ranges and ON/OFF.FeaturesOscilloscope current probe for applications in industrial and power environmentsAnalyze, measure and accurately display distorted current waveforms and harmonicsCurrent range from 100mA to 100AAC/DCDirect BNC connection to scopeJaw designed for easy maneuvering in crowded spacesApplicationsOscilloscope applications in industrial or power environmentsAnalysis and measurement of distorted current waveforms and harmonics

author: trevwhite
author_rank: Frequent Contributor
timestamp: January 02, 2016, 04:49:37 pm
content: Thanks, its certainly an interesting option and much cheaper,smaller and possibly more reliable as its newer.

author: trevwhite
author_rank: Frequent Contributor
timestamp: January 02, 2016, 05:14:23 pm
content: http://quan-diy.com/misc/multimeter/etcr.htmThis one seems to have similar specs but is very cheap.Any suggestions with a better spec? Thr SL261 datasheet stated +-50mA. I thinking this is zeroing range or is it noise?

author: edavid
author_rank: Super Contributor
timestamp: January 02, 2016, 05:38:06 pm
content: To answer the original question, in the US a complete working system usually goes for $300-500.

author: trevwhite
author_rank: Frequent Contributor
timestamp: January 02, 2016, 06:24:51 pm
content: Thanks. How reliable would a AM503B be considering its age? It sounds a bit tricky to fix if it goes wrong but its specs lookgreat with a A6302

author: Alex Nikitin
author_rank: Super Contributor
timestamp: January 02, 2016, 07:23:47 pm
content: This combination is a great tool. I had to clean the switches and contacts in my set after I've bought it, however there is nothing for similar money that comes close IMHO, old or new. Here is an example of it's performance - 10MHz square wave current through 50 Ohm terminating resistor. The top trace is the current, delayed by about 40ns, the bottom trace is the voltage on the resistor.CheersAlexP.S. - I've paid about £300 - in 2008! Works fine all these 7+ years.

author: edavid
author_rank: Super Contributor
timestamp: January 02, 2016, 08:35:59 pm
content: Quote from: trevwhite on January 02, 2016, 06:24:51 pmEh, not bad, but you can't get complete schematics. A plain AM503 is more repairable, since there's a complete service manual.

author: lukier
author_rank: Unknown
timestamp: January 02, 2016, 10:19:35 pm
content: Quote from: edavid on January 02, 2016, 08:35:59 pmThere is AM503A service manual and schematic online, but more hard to find.All of these amplifiers are difficult to repair, mostly due to Tek custom stuff. I think (based on tesla500 repair video) that only TCPA300 is made with COTS components.In plain old AM503 that I have the output amplifiers are Tek hybrids. Also attenuator resistor inserts and a lot of uncommon mechanical parts (e.g. dual ganged pot for offset that I had to fix). In general I'm not a fan of stuff from this era, as everything looks like a prototype bodge. With modern stuff it is much easier to tell what's original, what's factory bodge and what has been reworked.AM503A has also custom output amplifiers ans Tek hybrid module for the attenuator. I have no idea about AM503B, but I would expect it is very similar to AM503A.I have A6302+AM503 and I've been looking for AM503B for a while, but I fail to understand the eBay pricing of these things, way too expensive. I get it that the A6302 probe is rocket science, still being produced under new names and brands, probably a lot of manual work during manufacturing, mu-metal heat treatment is not an easy task, as is polishing the core surfaces to 1um tolerances.The amplifier on the other hand is quite far from rocket science. Most stuff there is < 100 MHz, amplifier for the Hall, feeding a power amplifier that provides bucking current for the transformer coil, then attenuator and output amplifier into 50 Ohm. Modern RF guys would probably consider it DC

author: trevwhite
author_rank: Frequent Contributor
timestamp: January 03, 2016, 01:53:44 am
content: Well I was thinking that stuff has to fail eventually and these things are maybe 40 years old. Maybe caps are the most likely to fail which can be replaced.Do the probes just keep on working?

author: edavid
author_rank: Super Contributor
timestamp: January 03, 2016, 02:43:38 am
content: Quote from: trevwhite on January 03, 2016, 01:53:44 amUntil you drop them

author: icpart
author_rank: Regular Contributor
timestamp: January 03, 2016, 06:06:29 pm
content: Hi guys. Few days ago I bought on eBay at very good price working T501 plug-in power supply with AM503 amplifier. And now i am looking for A6302 or 6303. Can you advise me what to look for when buy that sort of probes because I know they are very fragile and they are also very old.P.M.A am little angry because last month I missing two ebay auctions with cheapest price for that current probes that I ever seen.

author: trevwhite
author_rank: Frequent Contributor
timestamp: January 04, 2016, 03:31:55 pm
content: Well I have invested in a TM502A+AM503B+A6312. Its cost a bit but the specs look awesome(if its all working). Seems as long as I dont drop the probe the only possible vulnerability is the AM503B but its a chance worth taking given the performance.I did look at the cheaper probes but in the end I wanted better performance.Hoping it arrives all working.

author: guido
author_rank: Regular Contributor
timestamp: January 04, 2016, 06:23:29 pm
content: Here's a dump of the processor in case it would fail

author: trevwhite
author_rank: Frequent Contributor
timestamp: January 05, 2016, 03:13:14 am
content: Thanks, what is the processor? There seems to be little info on AM503B insides which is a shame.

author: guido
author_rank: Regular Contributor
timestamp: January 05, 2016, 10:46:29 pm
content: Philips P87C528EBPN from 1995Tek 160-9569-02 W5

author: trevwhite
author_rank: Frequent Contributor
timestamp: January 06, 2016, 06:37:49 am
content: Guido, what is your experience with the AM503B? Sounds like you have one and opened it up?

author: guido
author_rank: Regular Contributor
timestamp: January 06, 2016, 09:24:14 pm
content: Hi,Yes i have one and opened it up. Had to replace the battery and i read the processor just in case it would break.That's it as it works fine. Got a A6302 with it.Don't use it that much, but i got itverycheapIt's one of my more modern 5xx plug-ins.I also found no further info, like a proper service manual or schematics.And you need a GPIB test fixture for calibration, which i do not have.

author: trevwhite
author_rank: Frequent Contributor
timestamp: January 07, 2016, 01:45:39 am
content: I think the test fixture enables comms? Maybe just converts to rs232 so might be able to bypass this?Has your unit held its calibration well?

author: guido
author_rank: Regular Contributor
timestamp: January 07, 2016, 07:43:43 pm
content: I don't have the tools to do a proper verification or calibration.Did some measurements, it seems a bit off (if my amp meter is correct).But it's for looking at a waveform, not accurate measurement. Just like a scope for voltages.Last cal was 2007. The fixture connects with gpib. Don't think it's serial towards the processor.A google on the part number gives two hits to the installation manual (679-2836-02)