Current Probe Recommendation - Page 1
Forum section: electronics / testgear

author: krisk
author_rank: Contributor
timestamp: December 28, 2017, 09:10:27 am
content: Hello,I'm looking for current probe in the price range of the 1000USD. Mostly for general purpose measurements DC + AC, like LED drivers, SMPS (mostly in the switching frequency range up to 200kHz ).I think that the probe accuracy is not my first priority and 5% should be quite enough, current range of 20A pk-pk should be ok, but of course more means better. The bandwidth, that's good question?Currently my first choice is Aim-TTi I-prober 520, but I have also found something called ICP5050 on Aliexpress:https://www.aliexpress.com/item/Oscilloscope-Probe-Accessories-ICP5050-current-probe-50M-20A/32827427938.html?ws_ab_test=searchweb0_0,searchweb201602_5_10152_10151_10065_10344_10068_10342_51102_10343_10340_10341_10084_10083_10304_10307_10301_10312_10313_10059_10314_10534_100031_10604_10103_10605_10594_10107_10142,searchweb201603_36,ppcSwitch_7&algo_expid=cd61b2bf-5d3d-4b68-b627-232b0fab29d1-22&algo_pvid=cd61b2bf-5d3d-4b68-b627-232b0fab29d1&transAbTest=ae803_5&rmStoreLevelAB=5The ICP5050 seems to be Chinese clone of some Tektronix probe, but if its worth anything ? Maybe someone had experience with it? Or maybe you have others ideas what to buy in this price range.Thanks for help.

author: trevwhite
author_rank: Frequent Contributor
timestamp: December 28, 2017, 09:28:44 am
content: AM503B with A6302 is awesome or A6312. They are old tech now but are brilliant for all sorts of current measurement.ThanksTrev

author: Someone
author_rank: Super Contributor
timestamp: December 28, 2017, 09:39:05 am
content: As above you can find Tektronix current probes with outdated interfaces in your price range, the A6302 and TCP202 are easy to obtain and power. Even Lecroy AP015 or CP030 if you're feeling adventurous.

author: Russ
author_rank: Regular Contributor
timestamp: December 28, 2017, 09:53:34 am
content: These probes ROCK! I have and use the Brymen probes and quite satisfied with them. But these probes are really nice too.http://probemaster.com/8000-series-test-leads-only/Russ

author: HighVoltage
author_rank: Super Contributor
timestamp: December 28, 2017, 11:46:13 am
content: How about the AMEC SL261http://aemc.com/products/html/moreinfo.asp?id=20201&dbname=productsThe same one is available under Tektronix, Agilent/Keysight, Fluke trade names/branding

author: tecman
author_rank: Frequent Contributor
timestamp: December 29, 2017, 12:48:30 am
content: Look for a Tek 6042. They are older, but solid performers. DC-50 MHz Biggest problem is they have DC drift over time, so you need to trim the offset every 15-30 minutes. Only takes tens of seconds. You can snag one on ebay for a few hundred $paul

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: December 29, 2017, 01:47:57 am
content: Quote from: tecman on December 29, 2017, 12:48:30 amAlso extremely fragile and difficult to calibrate, and often have broken cables where the cable enters the cabinet. Plus it's a unreplaceable cable type and it is quite stiff these days.A single drop of the probe can damage it irreparably. The transformer is a custom potted part. You aren't fixing that.There was once a NOS Tektronix transformer kit on eBay for 25$. Somebody, I don't know who (somebody), snapped it up the moment I, I mean he, saw it. You aren't going to find that again, probably ever.The point is, as much as I like these things, they are a lot more than a few hundred $ these days, and are too fragile.I'd go for the AM503 too.

author: _Wim_
author_rank: Super Contributor
timestamp: December 29, 2017, 08:49:53 am
content: Quote from: krisk on December 28, 2017, 09:10:27 amMore also means that small current changes will not be visible any longer (buried in noise/not enough sensitivity). What is the smallest currect difference you want be able to measure? That is also an important selection criteria.

author: krisk
author_rank: Contributor
timestamp: December 29, 2017, 01:52:52 pm
content: So nobody recommends Chines inventions :]?Quote from: _Wim_ on December 29, 2017, 08:49:53 amI'm planning to use this probe mostly for small and middle range AC / DC and DC/DC converters. We can assume 1W to 100WDespite price TCP202 seems to be pretty nice stuff and there is even original Rigol adapter for my DS4024 ("T2R1000 Active Probe Adaptor") btw there is any other way to connect this probe to RIGOL scopes? Especially low cost ones like DS1000Z series.Does AM503B with A6302 / A6312 also suffers from DC offset drift?I have seen some AM503 units (not AM503B) on Ebay in good price ... do you think its worth to buy? Or it has to be AM503B?

author: trevwhite
author_rank: Frequent Contributor
timestamp: December 29, 2017, 02:03:00 pm
content: I have the AM503B and I believe it is superior. It's been awesome in many situations. I don't use it often but when I do it's always been great. There is offset adjustment on the AM503B and you do have to degauss it regularly but the unit tells you when it needs to be done and that just entails removing the probe from the circuit being measured and pressing a button.I am paranoid about looking after the probe. I have it in a foam box all the time to ensure it isn't damaged and it only comes out the box for use. I never leave it on my bench when not in use.I am in the UK and I found a set from a US supplier. Always seem to be a few going for silly money.ThanksTrev

author: capt bullshot
author_rank: Super Contributor
timestamp: December 29, 2017, 02:10:35 pm
content: Quote from: krisk on December 29, 2017, 01:52:52 pmAM503B does the offset adjust automatically, by pressing a button. AM503 needs manual adjustment. But the main source for DC drift is the A6302 itself, so it doesn't matter too much which amplifier you use. The AM503B blinks the offset LED after some time to remember you to re-adjust, the inverval is short after turn on and gets longer then, according to the warm-up of the probe sensor itself. But it's a simple timer, not some kind of "drift detector".The amplifiers ofter are quite cheap on ebay, they are useless without the probe. The probes can be still quite expensive.If you can get your hand on a modern Hioki (https://www.hioki.com/en/products/detail/?product_key=5783) one, these are better in terms of drift and noise than the old Tek ones. Expect them to be quite expensive.

author: krisk
author_rank: Contributor
timestamp: December 29, 2017, 02:28:21 pm
content: Quote from: trevwhite on December 29, 2017, 02:03:00 pmSounds greatQuote from: trevwhite on December 29, 2017, 02:03:00 pmCan you recommend me any company or ebay seller where you buy it?I'm bit afraid to buy it on the ebay without recommendation especially from remote country like China ;]I also don't know if probe / amplifier needs to be somehow recalibrated in the certified lab after years of usage?I'm also looking for some company specialised in selling used lab equipment (preferably based in EU) So if someone can recommend I would be pleased :]

author: krisk
author_rank: Contributor
timestamp: December 29, 2017, 02:37:30 pm
content: Quote from: capt bullshot on December 29, 2017, 02:10:35 pmHioki 3276 - looks like great stuff :] but it's completely out of my price range

author: trevwhite
author_rank: Frequent Contributor
timestamp: December 29, 2017, 02:50:22 pm
content: I do not know the company I used now but they sold a lot of stuff and the communication with them was good so, it was a gamble but I felt they were okay. They had been selling for years and were a proper company with an address in the states. I think you have to open a communication with the seller. If they say sold as seen and no way to test and all that then as people have said, the probes can not be fixed so I would not take the risk. You want someone who tells you at least that they have tested it. Then you are covered through Ebay, etc.Toploser is the man on here for lab equipment. Great prices and trustworthy.

author: Neomys Sapiens
author_rank: Super Contributor
timestamp: December 29, 2017, 05:45:06 pm
content: There is already a thread pertaining to this:https://www.eevblog.com/forum/testgear/acdc-current-probe-for-scope/I can only add that the AM503B will work with probes that the AM503/503A cannot compensate for anymore.They seem to have improved the capability for this along with the user interface.If you have a scope with TekprobeII, then consider getting a TCP202. If not, any AM503 +P6042 will be top choice, as all others except the most expensive ones still struggle to achieve comparable precision and bandwith.

author: Someone
author_rank: Super Contributor
timestamp: December 29, 2017, 10:31:30 pm
content: Quote from: krisk on December 29, 2017, 01:52:52 pmIsn't Instrance an Indian company?Quote from: krisk on December 29, 2017, 01:52:52 pmThey use a very simple interface which only requires power to work (no digital handshake etc) which people on this forum have already experimented with extensively:https://www.eevblog.com/forum/projects/tektronix-tekprobe-power-supply-for-agilent-rigol-and-other-oscilloscopes/or you can buy the Tektronix solution:https://www.tek.com/datasheet/probe-power-supply-1103

author: Howardlong
author_rank: Super Contributor
timestamp: December 29, 2017, 11:19:13 pm
content: I have the AIM TTi prober 520 you mention, had it for a couple of years. There are some handy features such as PCB trace probing and the small form factor of the clamp. I find it fiddly to set up though, and it needs frequent manual adjustment: the orientation of it is often affected by the Earth’s magentic component so you end up with DC offset if you don’t null it out. There’s also the hassle of the external PSU and general setting up.If I can, I use resistive shunts rather than use the probe, but sometimes it’s useful to be able to measure less intrusively. I think if my primary day job was designing and prototyping SMPS all day I’d find it frustrating to use, but for the odd design every few months I find it’s a reasonable compromise.Mike and Dave did a couple of vids on it,https://youtu.be/_xvpLisMr7whttps://youtu.be/kmCvrGVtC0M

author: krisk
author_rank: Contributor
timestamp: January 02, 2018, 12:52:01 pm
content: Quote from: Someone on December 29, 2017, 10:31:30 pmTo be honestly no ideaI google it and I found this web pagehttp://www.instrance.com.cn/en/ProductView.asp?ID=63I was trying to find any technical review or forum post to get feeling about its quality but no luck so far ...Do you have any experience with this company?Quote from: Howardlong on December 29, 2017, 11:19:13 pmI have also been using this probe for the while, for me PCB tracing is not very useful, results are very dependent on probe position (angle, rotation etc.).Do you think that this probe has sufficient bandwidth for probing SMPS?

author: IDEngineer
author_rank: Super Contributor
timestamp: January 02, 2018, 06:19:38 pm
content: I keep looking for a current probe solution that gives reliable data down into the microamp (or even 10's of microamps) range. Don't need much bandwidth, even 50-100KHz would be enough.It's been so long since I used one of the venerable Tektronix probe+amp setups that I can't remember if its noise was low enough to yield useful data with such low currents, but when you consider the age of those probes and their calibration difficulties and so forth, I suspect it would be a challenge to get/keep them running.Most of today's current probes have a top end measured in 1/10/100's of amps. I generally ignore those because if its top end is 1A, expecting useful datasix orders of magnitude lowermight be asking a bit much.Any microamp range probes out there?

author: HighVoltage
author_rank: Super Contributor
timestamp: January 02, 2018, 07:37:40 pm
content: Quote from: IDEngineer on January 02, 2018, 06:19:38 pmYes, there are some current probes by Keysight, that have a 50uA range.TheKeysight N2820Afor instance.Industry’s highest sensitivityMinimum current range of 50 uAMaximum current range of 5 AWide dynamic range of >20,000:1 or 86 dBBandwidth:3 MHz - zoom-out channel500 kHz - zoom-in channelBut it comes at a price of $4,117.00https://www.keysight.com/en/pc-2241287/n2820a-high-sensitivity-current-probes?cc=US&lc=eng

author: IDEngineer
author_rank: Super Contributor
timestamp: January 02, 2018, 07:45:38 pm
content: Quote from: HighVoltage on January 02, 2018, 07:37:40 pmI wonder if this is a Keysight-manufactured probe, or a relabel like so many probes? The differential probe market, for example, is dominated by relabels from just a couple of actual manufacturers.EDIT: Looks like there's a single channel version (the N2821A) that is less expensive, at "only" ~$3K.However, I notice that they specifically list "compatible" oscilloscopes ("InfiniiVision 3000 X/T-, 4000 X-, 6000 X-, and Infiniium S, 9000 Series") so these may not be applicable to non-Keysight scopes.Anything comparable with an industry standard BNC connector? I haven't found one....

author: Someone
author_rank: Super Contributor
timestamp: January 02, 2018, 09:36:51 pm
content: Quote from: IDEngineer on January 02, 2018, 07:45:38 pmIt looks to be an in house design from them, the rebadged probes they sell from other OEMs appear on the other scope brands. Its "just" a differential amplifier across a burden resistor so there are plenty of other ways to do that such as the Tek ADA400 or higher performance Preamble differential amplifiers.Quote from: IDEngineer on January 02, 2018, 06:19:38 pm10's of microamps is possible for short term measurements at low bandwidths with the typical 15A/30A scope probes but the DC drift can be a little annoying if trying to log long periods. Add 10 or 20 loops through the probe jaw and use a strong low pass filter to remove the noise.Quote from: krisk on January 02, 2018, 12:52:01 pmNo experience at all, but at the price its selling for I'd stick with the proven brands and get a second hand Tek or Hioki (Lecroy/Agilent rebranded) probe.

author: HighVoltage
author_rank: Super Contributor
timestamp: January 02, 2018, 10:00:16 pm
content: Philips made a clamp on current probe a long time ago with an amplifier box.It was thePM9355It has a 1mA resolution and 70 MHz bandwidth

author: IDEngineer
author_rank: Super Contributor
timestamp: January 02, 2018, 10:23:55 pm
content: Quote from: HighVoltage on January 02, 2018, 10:00:16 pmGood find, but sadly it only goes down to <= 12Hz (e.g. not DC). Granted I didn't explicitly state that in my original question, sorry... when I said "50-100KHz" I meant from DC.(And I do have a soft spot for Philips test equipment. I still have a PM3214 dual channel delayed timebase scope right here on the bench, purchased brand new direct from Philips. In addition to one of the best trigger circuits I've ever used on any scope of any bandwidth, it has the rather unique feature of being double insulated... its BNC's aren't referenced to earth ground and it has a two prong captive line cord.)

author: HighVoltage
author_rank: Super Contributor
timestamp: January 02, 2018, 10:40:16 pm
content: Quote from: IDEngineer on January 02, 2018, 10:23:55 pmYes, that one does not work for DCHere is another current probe that does do DC but is limited to 1.5 kHzChauvin Arnoux P01120074A K2It is made to be used for DMM but with an adapter it works well for scope.I have been using this one for DC signals and slow ACRange: 0,1 mA...450 mA DC, 0,1 mA...300 mA RMS, 0,1 mA...450 mA peakThe built quality is amazingly good!http://www.datatec.de/Chauvin-Arnoux-K2-Stromwandler.htmIn regards to old Philips gear, I totally agree with you.The old Philips scopes are very special.I never owned a PM3214.

author: IDEngineer
author_rank: Super Contributor
timestamp: January 02, 2018, 11:28:04 pm
content: That one looks functionally a lot like the Hantek CC-65:http://www.hantek.com/en/ProductDetail_15_77.html...which I already own. The CC-65 is actually a reasonable current probe for DC-20KHz for currents above 10-20mA or so. Goes to at least 65A, so way above what we're talking about here, but isn't as useful in the mA ranges and utterly useless below ~10mA. Noise floor is just too high no matter how aggressively you limit your scope's input bandwidth.Looks like the K2 has about 100ximpliedbetter sensitivity based on the front panel switch (10mV/1mA). The CC-65 offers 1mV/10mA. The big question... how is the noise floor on the K2? All the gain in the world isn't useful if the signal is buried in noise.

author: HighVoltage
author_rank: Super Contributor
timestamp: January 02, 2018, 11:39:14 pm
content: Quote from: IDEngineer on January 02, 2018, 11:28:04 pmI will hook it up tomorrow to my scope and measure the noise floor.

author: IDEngineer
author_rank: Super Contributor
timestamp: January 03, 2018, 12:28:45 am
content: Quote from: HighVoltage on January 02, 2018, 11:39:14 pmExcellent, thank you!!!

author: korlatos
author_rank: Regular Contributor
timestamp: January 03, 2018, 12:38:13 am
content: Applied Physics 428D can measure down to 20uA from DC to 200 Hz. It is a modernized version of the old HP 428B.

author: IDEngineer
author_rank: Super Contributor
timestamp: January 03, 2018, 12:51:00 am
content: Quote from: korlatos on January 03, 2018, 12:38:13 amAnd the price...? Their website doesn't say. Maybe if you have to ask....It does say the bandwidth goes to 600Hz, though!EDIT: These appear to be flux gate based devices, similar to the AIM TTI I-Prober 520. I suspect they'll be higher performance, though.EDIT: Just found a non-authoritative comment that suggests the price is ~$4000.

author: korlatos
author_rank: Regular Contributor
timestamp: January 03, 2018, 01:45:59 am
content: Per 428D data sheet, the -3dB BW is 200 Hz on the lowest range (10 mA FS). If you are patient, you can buy a used 428D without the probe for a couple hundred bucks on fleabay. Used probes go for about $50.

author: HighVoltage
author_rank: Super Contributor
timestamp: January 03, 2018, 05:13:23 pm
content: Quote from: IDEngineer on January 03, 2018, 12:28:45 amOK, I hooked the K2 current probe up to two scopes and one DMM.And here are the results for signal and noise floor.As long as you are using "high resolution" or "average mode" for the acquisition, the slow signal looks perfectly alright and the noise is suppressed.In normal acquisition mode, the Agilent MSO7034B has a peak to peak noise of 5.8 mA.The 6000X scope shows about 5 mA Pk/Pk noiseThe real signal has a 100 ns rise time.The scope shows 185 us rise time because of the probes bandwidth limitation.For slow signals, this probe is working well.In this case, the 15 mA signal has a duration of 1 ms and it shows OK.The price is reasonable and as I said before, the built quality is excellent.

author: HighVoltage
author_rank: Super Contributor
timestamp: January 03, 2018, 05:18:57 pm
content: And here are some pictures of the probeCHAUVIN ARNOUX K2

author: IDEngineer
author_rank: Super Contributor
timestamp: January 03, 2018, 07:47:02 pm
content: Thank you very much for taking and posting this data, complete with screen shots!Looks like this probe would be useful down into the low 10's of mA, perhaps even a bit lower. And I am a fan of the clamp style over the flux ring style, since getting repeatable results with the latter is so orientation sensitive (and I don't mean to the Earth's magnetic field, I mean even to the trace/wire you're measuring).

author: krisk
author_rank: Contributor
timestamp: January 05, 2018, 10:28:24 am
content: Which one do You think will be better: AM503B with A6302 or TCP202I briefly read the spec the A6302 and TCP202. They seems to be very similar in the therms of performance ...But TCP202 seems to be much newer designWhat would you chose ?

author: capt bullshot
author_rank: Super Contributor
timestamp: January 05, 2018, 10:52:24 am
content: Don't know the TCP202, never had one to try out myself. Sometimes I use a Hioki (available as Yokogawa, Agilent, ... rebranded), so I can give a bit of comparison:A modern Hioki one (e.g. the 3267 model) is clearly better in terms of drift and noise than the A6302 / AM503 combo, so I'd expect the TCP202 being better too, but I don't know if Hioki or other technology is inside the TCP202, so don't nail me down on the TCP202.Noise and drift results most from the Hall sensor element, so the choice of a particular AM503 model doesn't make a big difference with the A6302.

author: Someone
author_rank: Super Contributor
timestamp: January 05, 2018, 10:46:56 pm
content: Quote from: HighVoltage on January 03, 2018, 05:13:23 pmThanks for the details as it looks like it has more noise than the contemporary Tek or Hioki, we'll assume that first image with the rise time is in averaging mode? Tek have come down a long way with their current probe pricing and still have the best noise performance, what pricing are you seeing for the Chauvin-Arnoux K2?

author: Neomys Sapiens
author_rank: Super Contributor
timestamp: January 06, 2018, 02:31:38 am
content: Quote from: krisk on January 05, 2018, 10:28:24 amI think that they are very close regarding parameters. If you want flexibility, get an A6302 with AM503x, as you can operate with any scope without a pesky 1103 Power Supply. If you use a scope with a TekProbeII interface, and maybe even travel with it, try to get a TCP202. In this application I like it much, along with the Tek HV differential isolator, which also works directly from the interface.

author: krisk
author_rank: Contributor
timestamp: January 06, 2018, 02:08:12 pm
content: I did probe comparison and hmm I don't understand System noise parameter... it seems like A6302 has only 250uA (up to 200MHz) where TCP202 has 2,5mA (for only 20MHz bandwidth)? Or I'm missing something???For the rest of parameters It looks like TCP202 has much better performance in high frequencies (above 1MHz) it also has better "Ampero-second product" so it theoretically better for high current spike measurement even if A6302 has higher current rating (20A).Does anybody know, what is minimal current which can be measured by A6302, TCP202 probes?I'm also wondering if A6302 and TCP202 are the some product class. Or at the time when they were sold there was some thing better ? (for A6302 there is 100MHz version, I think A6312)

author: krisk
author_rank: Contributor
timestamp: January 06, 2018, 02:19:21 pm
content: I'm also wondering how TCP202 will work with Rigol scope DS4024?Rigol T2R1000 Active Probe Adaptor and TCP202 seems to be nice compact solution which can save space on my desk:))

author: alm
author_rank: Super Contributor
timestamp: January 06, 2018, 06:10:37 pm
content: Never tried it, but keep in mind that the TCP202 can draw more current than most voltage probes, and sometimes even induce ripple in the voltage rails feeding the probe power. The way these probes work is that an opposing current is fed through the transformer to keep the current measured by the Hall sensor zeroed. So if you are measuring 10 A, it will have to source 10 A / N (turns ratio). This is where the TM-500/5000 series amps are superior, since they have a dedicated power supply. No idea if this will be a problem with the Rigol adapter.

author: MarkL
author_rank: Unknown
timestamp: January 06, 2018, 08:42:49 pm
content: I have both a TCP202 (w/1103 power supply) and a A6302 (w/AM503 amp). Below is a comparison of the noise levels for a 0 to 2.0mA square wave @ 1MHz using a Keysight MSOX3104A.The first photo shows the two probes on their most sensitive scale (Ch1 = TCP202, Ch2=A6302). Since the TCP202 has no scale adjustment (fixed 0.1V/A into 50ohms), all the amplification happens inside the scope. As you can see, the TCP202 is pretty much useless for signals that low. Admittedly, much of that noise is from the scope itself since it's on maximum sensitivity (1mV/div), so if you had a low noise front end you could do better. BW limiting to 20MHz just about halves it, so that's another approach.If your signal permits, you can use averaging for a much cleaner result. The second photo shows a 256 average. However, the TCP202 signal is still too low to be very useful. This particular scope has a "magnify" feature, which can be used to increase the amplitude of the displayed waveform, third photo, magnify in purple. It can be handy if your scope has it too, but it's still pretty noisy.If you're wanting to measure small signals, I would definitely go for a A6302 before a TCP202. The A503x amplifiers can also be used with the larger A6303 probe for even higher current measuring capability.I also have the adapter that allows me to plug the TCP202 directly into the Keysight scope, so truth be told, I actually end up using the TCP202 most often because of the convenience factor. The Rigol T2R1000 adapter lists the TCP202 as supported, so one would presume they've done the design and testing to meet the power requirements for the list of supported probes.If you're looking to buy a used TCP202 or A6302, make sure you get one where the housing is not cracked around the core closure (or pieces missing, I have seen). It can prevent proper seating between the core halves and ruin your measurements.I've also used the i-Prober 520 and I agree with other posters that it's far too fidgety and, I would add, limited in bandwidth for use as a general purpose current probe. I wouldn't go there.

author: krisk
author_rank: Contributor
timestamp: January 09, 2018, 02:57:57 pm
content: MarkL thank for your input.I have found forum topic about AM503B + A6302 and its noise:https://www.eevblog.com/forum/testgear/tektronix-am503b-current-probe-amp-noise-levels/msg1027432/#msg1027432From this conversation I'm assuming that AM503B + A6302 has noise flor around 5-6mVp-p and it's same in all amplifier ranges.Does it mean that probe has always noise of the 0.5 division regardless amplifier settings?For TCP202 i believe it's different, and it has noise level which is not scaling with amplifier settings because TCP202 has only one, fix gain settings 0,1V/A, ma I right?Quote from: MarkL on January 06, 2018, 08:42:49 pmAs you wrote, on the lowest scope range 1mV/div reading is noisy but its also due to scope noise. But what about higher currents? I would expect that TC202 will have much better performance regarding noise.In the TCP202 manual there is chapter "Increasing Measurement Sensitivity". If we count 4 loops we should get measurement multiplied by the factor of 5.Question is what impedance it will introduce .... ? For the air coil with 4 loops inductance is as low as 0,3uH but here we have probe core ....BTW I'm bit afraid of A6302 & AM503 due to its age and possible fails ... capacitors e.g. and I'm pretty sure that it won't be easy to repair it

author: MarkL
author_rank: Unknown
timestamp: January 09, 2018, 07:34:12 pm
content: Quote from: krisk on January 09, 2018, 02:57:57 pmThere is some noise introduced by the AM503 on more sensitive ranges. To put some numbers to it, using the scope's measurement function and using the previously shown settings (10mV/div @ 200ns/div), the scope itself is 2.8mVpp for a baseline. With the AM503 and A6302 and no signal input to the probe for different AM503 settings, here is the measured noise:1mA/div 8.8mVpp2mA/div 7.6mVpp5mA/div 3.6mVpp10mA/div 3.4mVpp20mA/div 3.2mVpp50mA/div 3.1mVppClearly there's some additional amplification element that's switched in for the two most sensitive ranges since the noise floor more than doubles.QuoteRight.QuoteAt higher currents the signal will be much larger than the noise floor, so I'm not exactly sure what you're asking. What I was trying to point out in my previous post was that if you're trying to measure small signals, the front-end amplifier in your scope will factor largely in your success with the TCP202. My front end isn't the best, but it's not the worst either. The AM503 removes this dependency from the scope.QuoteIf you take a look further in the manual, there are charts Fig. 15 and Fig. 17 which show the insertion impedance for a single wire (1 turn) and 10 turns. 5 turns would roughly a factor of 5 times the single wire chart, but a more accurate estimate would be to use the 10-turn chart and divide by 2.QuoteI hear you on that and it's a valid concern. Old equipment can be a purchase risk and a maintenance chore. I can say I've never had to replace filter caps on mine (had it 15, maybe 20 years). The only service it's needed was a broken mechanical link on the DC Level control and cleaning of the range contacts. But no matter how much I cleaned the contacts, it was always a little crunchy after not being used for a while. I've gotten used to it.The TCP202 does have a problem picking up power supply noise when used with a TDS3xxx scope. That's not your situation, I know, but be aware it does need a clean supply if you get one of those adapters.And both of these probes drift quite a bit when trying to make low-level measurements. It can be annoying to constantly zero out everything before taking a measurement snapshot.

author: nctnico
author_rank: Super Contributor
timestamp: January 09, 2018, 10:17:20 pm
content: The question however is how much accuracy the OP needs. The cheaper current probes from Ebay (say in the $200 to $300 range) do a decent job for SMPS work because you are typically more interested in the shape of the waveform than the value.

author: HighVoltage
author_rank: Super Contributor
timestamp: January 16, 2018, 12:55:31 pm
content: It looks like Keysight has a new current probe with a 1mA resolution and much better noise floor.TheKeysight N7026AThis one looks really promising for a clamp-on probe for low currents.Just the price tag is EUR 4.522,00 + VAT !

author: MarkL
author_rank: Unknown
timestamp: January 16, 2018, 03:21:42 pm
content: The N7026A looks great in comparison to their N2893A, but I wouldn't say it has a much better noise floor than the old AM503/A6302 combination, even given the higher BW. Here is a screen shot of the same settings on a AM503/A6302 and roughly the same signal as in the N7026A brochure. (The AM503 could obviously use some tweaking on the compensation, but I'm just pointing out the noise level here.)The N7026A BW of 150MHz and 30A continuous is a nice bonus, compared to the A6302 50MHz and 20A. But US$4800 is pretty steep. Ouch.Plus there's also the "lock-in" factor: The N7026A has a proprietary AutoProbe interface, so it can't be used with non-Keysight scopes and other equipment. That would kill it for me right there, better specs or not. I don't like my probing investment glued to my scope manufacturer, if I can possibly avoid it, since it creates a larger financial barrier in considering other manufacturers at scope refresh time (gotta re-buy all those probes). The TekProbeII interface, as old as it is, has become somewhat of a solution to that problem since a bunch of manufacturers support adapters to it.The OP said they have a Rigol DS4024 so I guess the N7026A is a no-go for them anyway.

author: Fludo
author_rank: Regular Contributor
timestamp: January 16, 2018, 05:22:11 pm
content: My first recommendation would be a Yokogawa 701933, but those are a little too pricey.After that would be a fluke i1310s, they have a standard BNC connection with internal 9V battery and will work on fluke multimeters.

author: woodchips
author_rank: Frequent Contributor
timestamp: January 16, 2018, 06:29:17 pm
content: Is it possible to come up with a simple test setup for current probes to measure noise etc?I would assume this would show two traces, one of the voltage waveform across a 1 ohm resistor and one of what the current probe sees. These can be reduced or increased to highlight the noise. Or anything better?I have to admit to a certain level of private interest here. I have three each of the 6302/AM503 and 134/6021 probes that are now no longer needed. I have done simple 'does it show a low and high frequency waveform' to ensure both the Hall and transformer parts are working, but perhaps something more is needed? I am reluctant to sell something that the buyer finds is not as described, rather just not sell them to save the hassle.

author: MarkL
author_rank: Unknown
timestamp: January 16, 2018, 08:18:36 pm
content: Quote from: woodchips on January 16, 2018, 06:29:17 pmAll the equipment you mention have performance verification procedures in their respective manuals. The AM503 procedure includes how to measure noise the Tek way.If you're trying to minimize returns from picky buyers, doing the verification is probably the best route, but it's a pain and much of it requires special equipment.Checking operation by sweeping a signal from DC (or whatever the lower limit is) to max BW through a shunt resistor and comparing the traces is a good idea. Wrapping multiple turns through the probe to simulate a signal with max current is also a good check. Make sure a square wave looks square at different frequencies. Cycle through all the range and switch settings and make sure they all work. Take a look at the noise levels and make sure they're not out of hand (or do the Tek noise measurement; that one is not so complicated).In your description say how it was tested, offer a 14 day return, and put tamper seals on key areas to deter unscrupulous buyers. But expect that no matter how much you do, some buyers are always going to claim an issue and ebay will almost always side with the buyer.You could always try to sell your stuff here in this forum, where it doesn't have to be so impersonal and contentious. This very thread is from someone looking to buy. krisk, please meet woodchips...EDIT: typo...

author: woodchips
author_rank: Frequent Contributor
timestamp: January 19, 2018, 04:35:38 pm
content: Knew I should have at least powered them on before posting, but they were all working a few years ago!Only find one AM503 system, hours of looking have turned up nothing. Even that system isn't working, getting lots of noise spikes at low frequency, presumably the Hall amplifier.The one 134 system I have tried is completely dead.Apologies to those who expressed an interest, doesn't look good.And I had just repaired my 7613 to test them with, that will be useful at least.

author: tautech
author_rank: Super Contributor
timestamp: January 19, 2018, 09:04:34 pm
content: Quote from: woodchips on January 19, 2018, 04:35:38 pmWhat probe comes with it ?Would you sell it as 'not working' ?

author: serggio
author_rank: Regular Contributor
timestamp: February 18, 2018, 03:36:12 pm
content: I think, HIOKI CT6841-05 + CT9555 also can be interesting

author: Hydron
author_rank: Super Contributor
timestamp: February 18, 2018, 04:27:20 pm
content: Quote from: woodchips on January 19, 2018, 04:35:38 pmWhere in the UK are you? (PM if you don't want to say in the thread).I ask as I have a known working AM503+A6302 setup (plus a slightly iffy A6303) and could potentially help work out what's wrong. Even just narrowing it down to dead/alive probe is worthwhile given how much an A6302 costs! (while you can pick up a probably-working/fixable AM503 amp for under $50 from the US or occasionally the UK, good luck getting a tested good A6302 probe for below a few hundred USD/GBP!).