POS ebay 'scope probes. - Page 1
Forum section: electronics / testgear

author: grumpydoc
author_rank: Super Contributor
timestamp: March 03, 2014, 09:32:17 pm
content: OK, there was a thread a while ago about cheap probes and whether they are "just as good" as more expensive ones.For most of the time a 100MHz probe does me fine and I have a couple of 200MHz probes for occasional use but I've lost four or five to damage recently and have been thinking of treating myself to a few decent high bandwidth probes to go with the LeCroy.However there is a Chinese seller who offers a range of probes at various bandwidths going up to 400MHz for the very reasonable price of £14.49 including postage.His ebay listing is herehttp://www.ebay.co.uk/itm/221309549262?var=520188807879&ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649. This isnota recommendation by the way - see below for details.How bad can it be? I asked myself, and even if it's shit it's not much money, so I bought one. Delivery was quite fast for an item from Shenzhen - I placed my order a week ago last Saturday and it arrived today so that's just 5 working days. Impressive.What I received I have to say matched the photos exactly. So much so there isn't too much point posing my own images. The package includes a trim tool and instruction booklet.This is already a little suspicious - the P6400 "400MHz" probe is listed with a rise time in x10 position of 2.3ns which actually corresponds to 152MHz if one uses the rise time = 0.35/bandwidth formula.So, we can debate what makes a good probe but shall we start with "actually specified anything like what's printed on the package" and "performsanythinglike the spec"?To start with here are some of my other probes faced with a 1ns (approx) rising edge. Click on the images for a larger version.First off one I've had for ages, labelled "AT-110" and (I think) claiming a 150MHz bandwidthOK, 2.67ns which corresponds to a bandwidth of 130MHz - not bad.Now a probe I bought off ebay about 2 years ago labelled pp-200 and claiming a 200MHz bandwidthNot a great front corner on this one but 2.31ns which equates to 150MHz. Slightly disappointing but they weren't too expensive.Shall we have a look at one of the Wittig W201's - notionally 100MHzOK, despite having the lowest rated bandwidth this has the best rise time 2.13ns which corresponds to 164MHz - fairly consistent with my previous measurement of the bandwidth of these probes.Finally the P6400 - remember this is supposed to be a 400MHz probe, or maybe a 150MHz one I'm no longer sure.Errr, what the actual f**k - 3.75nsMeasuring the response the 3dB point is just past 80MHzBasically this is a 60MHz probe with a 400MHz label - and people wonder why anyone might get uptight about cheap probes from ebay.I'd not measured the "200MHz" probes before but it's clear that they aren't anything like the bandwidth that they claim (also an ebay purchase - go figure) but my latest acquisition really takes the biscuit.Don't buy these probes.

author: Vgkid
author_rank: Super Contributor
timestamp: March 03, 2014, 10:04:49 pm
content: I wonder how the texas branded oscilloscope probes perform, seeing as they are twice as expensive.

author: grumpydoc
author_rank: Super Contributor
timestamp: March 03, 2014, 10:34:28 pm
content: QuoteDon't know, do you have an ebay auction id?The W201's are rebranded Texas ones and they seem conservatively rated unlike most of the other probes that I have lying around.

author: Vgkid
author_rank: Super Contributor
timestamp: March 04, 2014, 12:38:17 am
content: http://m.ebay.com/itm/320787363068?nav=SEARCHregarding the 201, thats good to hear.here is an ebay link to ebayMore can be found on dx.

author: marshallh
author_rank: Unknown
timestamp: March 04, 2014, 04:05:27 am
content: Don't mess around, get a PP005 or PP006 off ebay for your lecroy... they run about $70-100 used. I have four of them and they are very high quality.500mhz is what they're rated for, but really that's optimistic. I haven't actually tried probing my avalancher with them, but I did use one to probe a 250mhz single ended clock, which showed as a 250mhz sine wave with some slight attenuation.I would use a Z0 probe for fast digital stuff like that anyway. (At 500mhz the passive 10x probe loads down the output driver a lot!)

author: linux-works
author_rank: Super Contributor
timestamp: March 04, 2014, 04:53:50 am
content: I recently bought a 2465b and was looking for 400mhz probes. the p6137 is the recommended one and they have been about $75 or so, used. to me, that's not asking a lot for a decent TEK probe.beyond a fairly low freq, the probe has to be matched to the scope (as it was explained to me). those bumps are compensations that are not done or done wrongly. my p6137 has at least 4 adjustments you have to tweak for LF and HF comp. that's how you do a 400mhz probe.if that one has a single screw adjustment, its junk. it won't ever show a faithful waveform beyond, say 20mhz or 50mhz. certainly not at 100mhz and higher.I wonder how long it will take before china realizes that they are not doing themselves any favors with the blatant lying and lack of quality in design and manufacturing. but I won't trust china for anything serious or critical. just won't do it. got burned too many times.

author: Rigby
author_rank: Super Contributor
timestamp: March 04, 2014, 05:14:46 am
content: Quote from: linux-works on March 04, 2014, 04:53:50 amyou sure? it is pretty easy to compensate a probe to match scope impedance.

author: BravoV
author_rank: Super Contributor
timestamp: March 04, 2014, 05:42:26 am
content: Quote from: Rigby on March 04, 2014, 05:14:46 amYes, very easy for common low frequency probe to scope match capacitance adjustment, its just a single adjustment point as normal probe does. Just chuck the alignment tool into the hole (labelled "LF COMP") at the middle of the probe's head like below.I guess he means the scope compensation adjustments for HF compensation at Tek P6137 probe. Its kinda complicated with four adjustment points (4 trimmers). Also it needs a high speed pulse-gen (Tr < 1 ns) and ultra high speed pulser (Tr <= 125 ps) standards to do that, definitely not as easy as LF. Also the above head needs to be disassembled 1st in order to get the access to those 4 trim points. Details ->Tektronix P6137 (PDF)

author: linux-works
author_rank: Super Contributor
timestamp: March 04, 2014, 06:35:51 am
content: exactly.I'm still new to the more advanced probe stuff - and I only knew about the single comp screw for the longest time. but it seems that you can further tune the probe to the scope if its designed to do that. and you can't get a random no-name probe to do this kind of thing, ever. you can LF comp it, sure, but there's more to the higher freq's than this.

author: Rasz
author_rank: Super Contributor
timestamp: March 04, 2014, 06:47:01 am
content: Thank you for the quick test.that rise time suggests P6060, P6100 at mosthttp://page.forweb.pl/osciloscopeprobe.pdfToo bad you didnt also get '150mhz' one to test. There are two possibilities. They are all the same shit with different sticker, all 'almost 100Hz' probes. Or the very best of the best of them are almost 100MHz, and when you order P6150 you get something ~P6020

author: BravoV
author_rank: Super Contributor
timestamp: March 04, 2014, 07:34:30 am
content: Quote from: grumpydoc on March 03, 2014, 09:32:17 pmPlease, post a photo or two of the test jig, and other details at the test connections if you think its important, I'm interested to learn how you did that, TIA.

author: sync
author_rank: Frequent Contributor
timestamp: March 04, 2014, 01:33:15 pm
content: Quote from: grumpydoc on March 03, 2014, 09:32:17 pmThese are worse than my cheap Chinese P6100 100MHz probes.My P6100 are OK. But I wonder if all these same looking Chinese probes are from the same manufacture and have the same quality.

author: nctnico
author_rank: Super Contributor
timestamp: March 04, 2014, 01:42:20 pm
content: IMHO the graph from the P6400 shows sign of impedance mismatch causing signals to bounce back and forth. The step in the signal is a sign of that. Things may improve if you load the pulse generator with a 10 Ohm resistor.

author: grumpydoc
author_rank: Super Contributor
timestamp: March 04, 2014, 02:23:10 pm
content: Quote from: marshallhI'm keeping a look out but they come up less often in the UK. I might just go for a decent, new, branded set from Farnell.Quote from: BravoVBasically with a fast pulse generator and a levelled sine wave source, with the probe connected via a probe-tip to BNC connector.For the pulse gen I'm currently using the cal output on the LeCroy which is not as bad as it sounds as ithasto be the Rolls Royce of cal outputs. It is adjustable from 10mV to 1V in 10mV steps and from 500Hz to 2MHz in 1-2-5 steps and can do either square wave or 25% duty cycle pulse. Connected to the 'scope by 1m RG58 and terminated at 50 ohms it measures at <1ns rise time.The other source is my Marconi 2024 which does 10kHz to 2.4GHz and is flat to +/- 0.8dBFor measurements the probes were LF compensated at 1kHz for best flat top and then the cal output switched to 2MHz for the measurement. The 'scope was set at 1ns/div for all the probes (I considered slowing the timebase for the P6400 but felt this might not show how crap it was).For the frequency response I put a tee on the output with a 50ohm terminator on one side and the probe on the other.The probes were connected using a probe tip to BNC adapter to ensure the shortest ground path.I have a TM500 with a couple of PG506's and an SG503 - unfortunately neither 506 works well but I might see if at least the pulse output on one of them is servicable.To be honest I grabbed several probes because I thought I'd measured the P6400 incorrectly at first.Quote from: linux-worksBetter quality generic probes have more complex compensation networks - somewhat like the Tek P6137 described by BravoV (though two or three trimmers seems the norm).Quote from: nctnicoMaybe - but probes aren't supposed to be "impedance matched" in that way. If I can set it up neatly with a good short ground path I'll have a go tonight and see if it makes a difference.If it were reflections though I'd expect the freqency response to bounce up and down as the reflections reenforced or cancelled the signal - however looking at the response it's flat(ish) up to 60MHz, then starts heading downwards hitting -3dB at 80MHz, -6dB around 100MHz and then falling off further with increasing frequency - doesn't look like reflections or impedance mismatch.The best interpretation is that a batch got mislabelled, the worst that it is deliberate.The vendor wants me to send the probe back but it's not clear that he intends to refund my postage which, at a minimum, for a signed service is going to be a tenner which is almost what I paid for the probe.Of course this is where the Chinese score - it's too expensive to return stuff

author: jpb
author_rank: Super Contributor
timestamp: March 04, 2014, 03:18:26 pm
content: A couple of brand new PP006As were sold recently for only about £55 each - I bid but mistimed it so missed out. I already have a full complement of 4 but was looking for a spare (I happened to see them and thought a spare would be nice).There are these ones, but they look well used and in my view a bit over-priced - they have been up there a while so you could make an offer :http://www.ebay.co.uk/itm/Lecroy-PP006A-500MHz-10-1-scope-probe-/271405921849?pt=UK_BOI_Electrical_Test_Measurement_Equipment_ET&hash=item3f310db639

author: The Electrician
author_rank: Frequent Contributor
timestamp: March 04, 2014, 03:30:39 pm
content: This thread may be of interest:https://www.eevblog.com/forum/reviews/cheapest-100mhz-oscilloscope-probes-hands-on-review/

author: marshallh
author_rank: Unknown
timestamp: March 04, 2014, 06:42:55 pm
content: FWIW the Lecroy 500mhz passives specified for your scope only have 1 trimmer, not 2.And yes the CAL output is a bit overengineered. Mine produces a step with about 350mhz bandwidth.

author: grumpydoc
author_rank: Super Contributor
timestamp: March 04, 2014, 08:14:08 pm
content: QuoteYes, I read that at the time. Interesting that you seemed to get quite good cheap probes.

author: pickle9000
author_rank: Super Contributor
timestamp: March 04, 2014, 08:32:44 pm
content: Quote from: grumpydoc on March 04, 2014, 08:14:08 pmThose probes have been around for quite a few years. I think most would consider them 60mhz. I consider them disposable but worth using (whenever possible) to avoid damage to more expensive probes.

author: The Electrician
author_rank: Frequent Contributor
timestamp: March 04, 2014, 09:01:22 pm
content: Quote from: grumpydoc on March 04, 2014, 08:14:08 pmThat thread is two years old. I wonder if these cheap probes have gotten worse over time. I may order some more for testing.Quote from: pickle9000 on March 04, 2014, 08:32:44 pmThe ones I tested were much better than 60 MHz as my measurements showed.In the two years since that thread, I've had a couple of the probes fail. They are not as rugged mechanically as a real Tek or Agilent probe, but even so, for the money, they have their place (preserving my good probes).

author: pickle9000
author_rank: Super Contributor
timestamp: March 04, 2014, 09:19:22 pm
content: @ The ElectricianI think that it is fair to say they are better than 60mhz. I guess my confidence in them starts to change at around that point. They are certainly worthwhile having around the lab and I personally use them daily. The best thing is the price. As for durability I have personally wrecked a couple by having them hit a soldering iron (among other things). They have held up well otherwise.

author: The Electrician
author_rank: Frequent Contributor
timestamp: March 04, 2014, 10:49:07 pm
content: Quote from: pickle9000 on March 04, 2014, 09:19:22 pmWhat causes your confidence in them to change at 60 MHz? Have you had some bad measurement results? You notice from my 2 year old results that the P6100 labeled probes were better; which probes have you been using?

author: grumpydoc
author_rank: Super Contributor
timestamp: March 04, 2014, 11:01:51 pm
content: Right, umm, OK could some more experienced heads offer a sanity check.For the rise time graphs that I posted earlier I had the probe connected to the cal output via a BNC adapter and the 'scope input set to 1Mohm.I've previously posted some frequency response curves for the W201 which were the same basic set-up except that the probe was plugged into an N to BNC adapter on the 2024 output.That is, for both cases the signal source was not terminated into 50 ohms.For the P6400 I changed the sig gen set-up so that I placed a tee on the output of the 2024 with a 50ohm terminator on one end of the tee and the probe was plugged in to the other again via a BNC adapter.I did this for two reasons:Firstly leaving the output unterminated obviously means the voltage is 2x what it would be if terminated into 50 ohms and means I have to remember to include the extra factor of x2 into working out what the p-p voltage should be on the 'scope or that the RMS value should be twice what the sig gen says. This was slightly annoying so I wanted to get rid of the extra factor.More importantly with the P6400 I was expecting 400MHz+ bandwidth (yeah, right) and the LeCroy is slightly bandwidth limited below 200mV/div. I wanted to wind the voltage up a bit so as to minimise errors due to the 'scope limitations. Doing so with a high impedance termination resulted in the 2024 not wanting to play ball and complaining I'd not terminated the output (well, it was right).So,.... I measured the pp-200 bandwidth this evening and got a -3dB point of about 330MHz. All well and good and dandy but, hang on a minute - didn't I get a rise time of 2.3ns for this probe, it should have a frequency response much lower than that.For confirmation I checked a W201 - again this did better than I expected with a -3dB point around 240MHz (I'd previously measured 150MHz).So I tried the same set-up on the cal output. I.e terminating that into 50ohms at the source and connecting the probe across the 50ohm termination. In this configuration bot the pp-200 and the W201 recorded rise times of around 1.2ns which would be closer to being consistent with the recorded bandwidths, but I'm a bit suspicious that it's "too good" for the W201 which should be measuring 1.5ns even if it does have a 240MHz bandwidth.The 2024 is obviously designed to be terminated into 50 ohms. The cal output on the LeCroy is also set up with a 50ohm source impedance so it "does the right thing" if terminated into 50 ohms.So - the question - for a true reflection of the probe rise time should I terminate the source with a low impedance and put the probe across that or leave everything at high impedance (I'm sort of thinking the former at the moment).It doesn't make a shred of difference to the P6400 - its rise time improved as well. To 3.6nsAnd repeating the bandwidth check was consistent - -3dB point was 84MHz (I measured 83MHz last night) so it remains a pile of crap.I didn't get to add a 10ohm resistor to the source but I did haul the PG506 down. The positive going output is clearly a bit poorly as I measured just over 2ns rise time but the negative going output was OK measuring 920ns on the 'scope - the result using it as the source with the P6400 was just as abysmal.Oh, I do realise that I ought to factor out the 'scope rise time - however for probe rise times in the 2ns range the 800ps or so of the 'scope doesn't really make a huge difference - for a pulse rise time of 1ns, scope rise time of 800ps and probe rise time of 2ns the displayed rise time would be 2.37ns.Quote from: marshallhThat could be a bit on the slow side - the specification actually says 1ns typical rise time

author: The Electrician
author_rank: Frequent Contributor
timestamp: March 05, 2014, 02:47:16 am
content: I see on eBay US a probe that looks like the one you got:http://www.ebay.com/itm/New-P6400-400MHz-Oscilloscope-Clip-Probe-For-Tektronix-HP-/291077790902?pt=LH_DefaultDomain_0&hash=item43c5969cb6But here's another one that is also designated p6400 and looks rather different at the scope end of it:http://www.ebay.com/itm/P6400-10-1-400MHz-High-Voltage-Oscilloscope-Alligator-Clip-Probe-FKG-/291087947637?pt=BI_Oscilloscopes&hash=item43c6319775Could somebody be lying to us?

author: Ivan7enych
author_rank: Regular Contributor
timestamp: March 06, 2014, 08:07:35 am
content: Quote from: The Electrician on March 05, 2014, 02:47:16 amI think, the probe with 1x - 10x switch can't be made good for 400-500MHz range.I have compared 3 probes I have -texas 300MHz,texas 500MHz (both are 10x probes only, without switches and with fine tuning on high frequencies, which helps to make overshoot minimal)and original active probe Tek P6243 2pf 1GHzAll probes have been tested with Tek TDS744A 500MHz, connected to test output signal of the oscilloscope.Here are 3 pictures

author: The Electrician
author_rank: Frequent Contributor
timestamp: March 15, 2014, 11:09:39 am
content: I ordered 2 of the P6100 probes from the same seller that I got the ones tested in the two year old thread.I'm sorry to say that these new ones are much inferior. I get a rise time that looks as bad as you got:You can see in the earlier thread that I got much better results two years ago. Too bad!I also checked the frequency response. The two year old probes ( I still have 3 of them) are 3 dB down at 250 MHz, and the response is flat until the rolloff; there is no ripple in the frequency response. The new ones are 3 dB down at 100 MHz, with ripple in the response.

author: David Hess
author_rank: Super Contributor
timestamp: March 16, 2014, 05:30:26 pm
content: Quote from: Vgkid on March 03, 2014, 10:04:49 pmI have a pair of x10 250 MHz Texas probes and they perform identically to a straight coaxial connection on my 300 MHz 2440 with the fast transition (better than 600 picosecond) outputs on my PG506. The Texas probes have a whole set of transient response trimmers in addition to the x10 compensation adjustment.My cheap x1/x10 100 MHz Aidetek probes work fine on my various 100 MHz oscilloscopes when tested in the same way.

author: EvanShultz
author_rank: Newbie
timestamp: June 03, 2015, 05:01:26 am
content: I often use Tek 013-0202-04 adapter on the end of my probes. You can see this adapter (shown as PN 013-0202-03) in the top left of the image athttp://www.tek.com/sites/tek.com/files/media/image/A000_0665-L.gif.Any idea if these P6x00 probes will support this Tek adapter?

author: codeboy2k
author_rank: Super Contributor
timestamp: June 03, 2015, 09:59:17 am
content: Apparently the Hantek PP150 x10 150MHz probe is about $17-$20 on Amazon, and is good up to 350MHz before it starts to roll offTesting the Hantek PP150 100MHz 10X probeseevblog member joeqsmith's channel has only a few short video's but they're all good, real world testing.His youtube videos deserve more viewsThanks Joe!His test of the Hantek PP4100 x100 100MHz high voltage probe broke when he wound up the amplifier to about 60V@100Mhz.Post-mortem teardown of the probe near the end of the video.Evaluating the P4100 100X 100MHz Oscilloscope ProbeThere's a thread here toohttps://www.eevblog.com/forum/testgear/teledyne-lecroy-waverunner-64xi/msg669308/#msg669308

author: joeqsmith
author_rank: Super Contributor
timestamp: June 06, 2015, 12:30:15 am
content: Thanks. Glad you enjoyed them.