Playing with Probes:  Guessing game. - Page 1
Forum section: electronics / testgear

author: BillyO
author_rank: Super Contributor
timestamp: March 04, 2023, 02:14:14 am
content: I had a meeting moved yesterday so had a few unstructured/unplanned minutes on my hands to burn.I broke out the Bodnar pulser and my SDS2000XP and started testing scope probes.Here are the results of 9 different probes I had lying about. Each was properly compensated before testing, Each was attached to the pulser through a 50 ohm feedthrough load and an appropriately sized probe-BNC adapter.I will update this post with which probe is which at a later time.In the meantime your mission, should you choose to accept it, is to decide which is the most expensive probe and which is the cheapest. The price range is approximately $6 to $600 (when new).They are in the order they came to hand...Update (prices are Canadian $):UNI-T - UT-P04 - 100MHz - $20Siglent - PP-215 - 200MHz - $54Hantek - PP-300 - 300MHz - $25Pico - TA-386 - 200MHz - $54No Name - P6139A - 500MHz - $42Tektronix - P6139A - 500MHz - $600 (est.)Hantek - PP90 - 80MHz - $6Siglent - PP510 - 100MHz - $40Instrustar - P2060 - 60MHz - $7I am quite impressed with #4, the Pico probe. Not the fastest rise time, but it seems well behaved otherwise. Some things that count against it are that it is a big probe, not re-buildable, no HF compensation and the compensation adjustment is in the probe itself (which probably helps make it so large).For #9, I'm sure the risetime measurement is being thrown off by the huge overshoot. It is the worst quality probe I have ever held.

author: tautech
author_rank: Super Contributor
timestamp: March 04, 2023, 02:19:15 am
content: Quote from: BillyO on March 04, 2023, 02:14:14 amLF/1kHz scope source ?No HF compensation/adjustment ?

author: BillyO
author_rank: Super Contributor
timestamp: March 04, 2023, 02:32:05 am
content: The 1KHz source was the SDS2000XP compensation output.Not having the HF compensation specs nor having access to the innards of all the probes, no special HF compensation was performed for most of them. That should have been done at the factory. Only one probe had the HF compensation checked and it was correct. That was the $600 probe.

author: lugaw
author_rank: Regular Contributor
timestamp: March 04, 2023, 02:45:40 am
content: Quote from: tautech on March 04, 2023, 02:19:15 amHow do you do HF compensation adjustment?

author: BillyO
author_rank: Super Contributor
timestamp: March 04, 2023, 02:53:44 am
content: Quote from: lugaw on March 04, 2023, 02:45:40 amSome high quality (read expensive) probes have HF compensation adjustments internally. You have to be able to take them apart to do the job and the specs/process have to be published. Better Tektronix probes fall into this category.

author: tautech
author_rank: Super Contributor
timestamp: March 04, 2023, 07:40:32 am
content: Quote from: BillyO on March 04, 2023, 02:53:44 amWell no.Based on what I said in reply #5:https://www.eevblog.com/forum/testgear/probe-into-probes-whats-up/All the 500 MHz probes I have ever seen have external HF trimmers and normally 2, both sealed with a plastic cap easily removed with a blade, not too sharp that might slice the plastic cap in half.Typically with these 500 MHz probes a 1 MHz rising edge of 1ns or better is specified and tweaking of dual trimmers....yes there are 2 in order to get the best step response and with NO overshoot !Here is where I run into trouble, why on earth not use the Bodnar pulser as a HF edge for adjusting HF step response, it's certainly faster that 1ns and at 10 MHz instead of a specified 1 MHz, why could that matter one damn ?How might we realistically accomplish these adjustments noting that when the Bodnar pulser is connected directly to a scope therecertainlyis overshoot....something we would normally trim out when compensating a probe.In my view and please correct me if you know otherwise, we should attempt toreplicatethe Bodnar step response when connected directly to a scope when making HF probe adjustments which flies directly in the face of HFtrimming out of all overshoot. Interesting dilemma IMO.We can see some of Bill's probes are in need of HF step response adjustment and based on what I learnt in Bill's probe-into-probes-whats-up thread I would pick probe 5 or 8 as his most expensive and 9 the cheapest......but I've been known to be wrong before !Adjustment instructions for Siglent SP3050A 500 MHz probe attached.

author: jonpaul
author_rank: Super Contributor
timestamp: March 04, 2023, 12:06:38 pm
content: good electronic engineering, no guessing involved.First read and learn about Oscilloscope Probes, then about ringing in return circuits and terminations.Highly recommendTektronix Circuits Concept bookOscilloscope Probe CircuitsProbe Measurementshttp://www.davmar.org/TE/TekConcepts/We use Tektronix probesP6136 ZoP6137 10xNever had any issues.No adjustments except the usual scope input capacity compThat is always at 1khz as only affects low I tiltBon SoiréeJonSee

author: mawyatt
author_rank: Super Contributor
timestamp: March 04, 2023, 02:53:10 pm
content: With all the discussions about the Tektronix Trade Secret "T-Coil" going on here.https://www.eevblog.com/forum/projects/wideband-modern-low-noise-analog-front-ends/25/This raised the question did Tek utilize the T-Coil in any passive voltage scope probes to improve bandwidth? The answer is yes, and they even used it in some current probes!!!Best,

author: BillyO
author_rank: Super Contributor
timestamp: March 04, 2023, 04:23:23 pm
content: Quote from: tautech on March 04, 2023, 07:40:32 amThat's nice to see. A lot of probes do not have any way to adjust them. The Tek P6139A does, but it requires partial dismantling to do it.I daresay that most sub $100 probes don't have any accessible adjustment and sub $50 probes probably have none at all.Kudos to Rob for taking a shot at it. I'll update the first post with the information.

author: jonpaul
author_rank: Super Contributor
timestamp: March 04, 2023, 04:47:11 pm
content: scope waves show ground wire ringing.USE BNC adapter or bayonet tip, no ground wirej

author: BillyO
author_rank: Super Contributor
timestamp: March 04, 2023, 04:48:37 pm
content: BNC adapters were used. Ground wires were removed.The ones with the least ringing are the Siglent probes.

author: tautech
author_rank: Super Contributor
timestamp: March 04, 2023, 08:05:57 pm
content: Here's an example of 2 quality (read $) passive probes compared against the Bodnar pulser waveform captured and used as a Ref waveform, plugged directly to scope and 50 Ohm input engaged.These probes were NIB but their HF response needed adjusting.If we are to follow the HF adjustment instructions to the letteranduse the fast edge of the Bondar pulser, in my view the probe step response need match the Ref waveform as well as is possible.One of the above adjusted for best/cleanest step response while preserving some overshoot to best match a 50 Ohm connection.Quote from: BillyO on March 04, 2023, 04:48:37 pmSame ^^^^Quote from: BillyO on March 04, 2023, 04:48:37 pmAs expected.Based on what I believe you have they will be PP510 and PP215, 100 and 200 MHz passive probes certainly without sufficient BW to resolve the edge speed and overshoot of a Bodnar pulser.

author: jonpaul
author_rank: Super Contributor
timestamp: March 04, 2023, 09:29:04 pm
content: Nice, any test with 400..500 MHz probes on 1 ghz BW scope ?Test with Zo probes in 50 ohm env ?Test with ghz FET probe?j

author: tautech
author_rank: Super Contributor
timestamp: March 05, 2023, 08:14:53 am
content: Quote from: jonpaul on March 04, 2023, 09:29:04 pmDone in that previous thread Jon, SDS6204A (2 GHz) used in all tests.https://www.eevblog.com/forum/testgear/probe-into-probes-whats-up/msg4678768/#msg4678768https://www.eevblog.com/forum/testgear/probe-into-probes-whats-up/msg4684580/#msg4684580Quote from: jonpaul on March 04, 2023, 09:29:04 pmSorry, don't possess one and never had the need.Instead 100x and 1000x and active and differential probes have met my needs......that change daily....today it was 4hrs driving a tractor for my son.

author: jonpaul
author_rank: Super Contributor
timestamp: March 05, 2023, 01:37:49 pm
content: RebonjourInteresting to compare your probe responses to a zero cost, low L ghz Zo...Précision 50 Ohm BNC coax>>> 450 or 4950 Ohm film or carbon comp 1/4 W resistance >>probe 50 ohm sourcesvery short shield to ckt rtn to minimize LserThe result is a Zo probe zero,cost very wideband low abberationthe series 450 Ohm is 10x. The 4950 Ohm is,100x.This is similair to Tektronix P6156.Bon SoiréeJon

author: BillyO
author_rank: Super Contributor
timestamp: March 05, 2023, 03:10:51 pm
content: Quote from: jonpaul on March 05, 2023, 01:37:49 pmI have a home made Z0probe, but it's not made with very good cable. I guess I could try to make another.

author: jonpaul
author_rank: Super Contributor
timestamp: March 05, 2023, 03:51:30 pm
content: For a Zo probe, the BW and pulse abberation, transients response is of course à function of the cable impedance , discontinuility, legnth.We,have,used Belden RG174 /U thin coax, 30..60cml.The best cables are very WB coax like Belden 1694.Tektronix made 50 cm précision 50 ohm coax BNCSee tektronix probe circuit bookshttp://www.davmar.org/concepts.htmland Belden Cable app notes,and specs.Jon

author: H3g3m0n
author_rank: Newbie
timestamp: March 09, 2023, 11:31:57 am
content: Anyone know if the Hantek - PP-300 is legit or some knock off?The Hantek website only lists up to PP-200 and I don't think they have scopes above 250Mhz.Although they do have PP-250's in some of the screenshots of the 250Mhz scopes so maybe they just haven't updated it.

author: BillyO
author_rank: Super Contributor
timestamp: March 09, 2023, 05:07:12 pm
content: Quote from: H3g3m0n on March 09, 2023, 11:31:57 amI ordered mine off Amazon.ca. They came in exactly the same packaging as the probes I got with my Hantek USB scope. None of them have Hantek written on them or on the "documentation" that came in the pouches. If you ask me I think Hantek just buy whatever from whoever. I don't think they make probes.https://www.amazon.ca/gp/product/B07P6DWRLZ

author: H3g3m0n
author_rank: Newbie
timestamp: March 11, 2023, 12:28:55 am
content: Quote from: BillyO on March 09, 2023, 05:07:12 pmThe PP-150 I got with my DSO2C10 does have Hantek written on the documentation, the documentation covers PP-80/150/200. But the probe itself just has PP-150 on the sticker, no Hantek branding.It's also a gray version (Hantek lists PP-XX0 and PP-XX0B with the B being the black version's). My one didn't come with a grounding spring (intentional as the documentation had no mention of one). I think the higher spec ones, (or maybe the black ones) do come with a grounding spring though. I think 150Mhz DSO2X15's come with black PP-200's since they need more bandwidth.I recently have ordered a PP-250 from Aliexpress, not yet arrived. I don't really have a good way to test them myself (and don't really have the knowledge). I'll see if there is any branding or not (not that really means much coming from Aliexpress).Quote from: BillyO on March 09, 2023, 05:07:12 pmWouldn't surprise me.But I would be skeptical about a cheap unbranded PP-300 probe really being 300Mhz though. They might all be PP-60's rebranded and sold at different price points.

author: BillyO
author_rank: Super Contributor
timestamp: March 11, 2023, 02:45:38 am
content: The PP-90s I got with my 6074BC were grey too. They also did not come with the ground springs.The PP-300s I got for my SDS1204X-E (well, "improved" SDS1104X-E) are black and did come with the spring grounds.However, I'm not too impressed with the overshoot on them and there is no way to adjust it. I recently got 6 of the Pico TA-386 probes for $10 each from a surplus seller. They are a pretty big probe but I'm really impressed with their performance and I may just get another 4 of them for the little Siglent to replace the PP-300s.

author: H3g3m0n
author_rank: Newbie
timestamp: March 17, 2023, 05:55:59 am
content: My supposed 'Hantek PP-250' arrived. No Hantek branding on the documentation, documentation mentions PP/250 and PP-300. Black with ground spring.The punchline is they sent it wrapped in cardboard to protected it. Specifically the back of a box for a UNI-T P05 probe. A probe that looksexactlythe same as the PP-250 I received except for the sticker on the connector with the model number.Although it's a 200Mhz probe, not at 250Mhz one. (I only really need 150Mhz so I'm fine).So I suspect that is probably what the PP-300 listed above is as well.Of course there's a good change they might be the same source that Hantek is using anyway. ThePP-250's pictured on the Hantek sitelook exactly the same as theUNI-T ones. Although Uni-T doesn't make a passive 250Mhz probe closest are the UT-05 200Mhz and and UT-06 300Mhz probes so unless they made a custom order they are shipping below spec probes.From my limited testing the rise looks much the same on both the grey PP-150 that came with the scope and the 'PP-250' I ordered from Aliexpress. The PP-250 does show more dips and rises not sure if that's the increased resolution or it causing increased noise.Quote from: BillyO on March 11, 2023, 02:45:38 amNice, those are like $65 AUD each.

author: bailliemccreight92
author_rank: Newbie
timestamp: March 24, 2023, 02:37:22 pm
content: Quote from: BillyO on March 05, 2023, 03:10:51 pmYou should change them, I also had bad wiring, because of them it shows me wrong data... By the way this was the cause why I lost several times here [spam link removed] because I didn't have the correct data and this interac casinos got that tricking me, but since I did this procedure - everything works fine and I am satisfied with it.

author: Akutchand10
author_rank: Newbie
timestamp: June 29, 2023, 08:38:49 am
content: Thanks for the information!