16 channel digital probe for HP54645D MSO? - Page 1
Forum section: electronics / testgear

author: carl_lab
author_rank: Frequent Contributor
timestamp: September 27, 2016, 04:49:48 pm
content: Where can I get a 16 channel digital cable and probes for HP54645D MSO for a reasonable price?Are there clones available?Can I make one DIY?

author: alank2
author_rank: Super Contributor
timestamp: September 27, 2016, 08:50:29 pm
content: I got one of these off of eBay and it works fine:http://www.ebay.com/itm/Agilent-HP-10089A-Logic-Probe-with-Flying-Leads-for-54622D-2-16-channel-scope-/351848422958?

author: carl_lab
author_rank: Frequent Contributor
timestamp: September 28, 2016, 07:29:29 am
content: Thank you!The cable looks like a normal floppy drive/HD flat cable.I thought the original was a woven/twisted pair type flat cable? Am I wrong or doesn't it matter?What do I need for 54645D scope?Pod 1 Data + J Clock,Pod 2 Data + K Clock,Pod 3 Data + L Clock,Pod 4 Data + M Clock,Pod 5 Data + N Clock orPod 6 Data + P Clock Logic Analyzer Probe?What's the differences?

author: alank2
author_rank: Super Contributor
timestamp: September 28, 2016, 12:02:47 pm
content: Quote from: carl_lab on September 28, 2016, 07:29:29 amIt is.Quote from: carl_lab on September 28, 2016, 07:29:29 amYou are right; I found this one to work fine, but signal integrity is likely better on the woven/twisted one.Quote from: carl_lab on September 28, 2016, 07:29:29 amThe kit I listed above comes with the Pod 4 Data + M Clock one, but I'm not sure what the differences are.

author: carl_lab
author_rank: Frequent Contributor
timestamp: September 28, 2016, 01:27:55 pm
content: Quote from: alank2 on September 28, 2016, 12:02:47 pmMaybe just the numbering (for "real" logic analyzers with more than 16 channels)?The PCB is just an extension without any components on it?

author: alank2
author_rank: Super Contributor
timestamp: September 28, 2016, 02:00:10 pm
content: Quote from: carl_lab on September 28, 2016, 01:27:55 pmThat is correct, no components, straight through.

author: Ice-Tea
author_rank: Super Contributor
timestamp: September 28, 2016, 05:06:35 pm
content: To be clear: it's not just floppy cable.There's resistor network in the head (see the teribly bad picture) which makes the input impedance 100k. Otherwise you'd have reflections up the yazoo.

author: alank2
author_rank: Super Contributor
timestamp: September 28, 2016, 05:22:09 pm
content: Ice-Tea is correct, the HP part of it has a resistor network in it. The floppy cable and adapter boards however are straight through.

author: Someone
author_rank: Super Contributor
timestamp: September 28, 2016, 10:23:12 pm
content: This comes up over and over on the forum, with the same misinformation each time. Agilent produced a lengthy document on the cabling including how to design your own interfaces to it, bizarrely its still on the Agilent site:http://cp.literature.agilent.com/litweb/pdf/5968-4632E.pdfThe document is "Probing Solutions for Logic Analyzers" should people need to find it in the future.

author: carl_lab
author_rank: Frequent Contributor
timestamp: September 29, 2016, 07:21:33 am
content: Yes, thank you!I think, this is what you mean:

author: carl_lab
author_rank: Frequent Contributor
timestamp: September 29, 2016, 07:48:17 am
content: What do you think, do I need the original woven ribbon cable?What about bandwidth?Could this cable be a reasonable compromise ($1.85/ft = $6.10/m)?http://www.surplussales.com/wire-cable/ribbon.htmlhttp://www.surplussales.com/wire-cable/pdf/wrc-468-2829-050.pdf

author: georgd
author_rank: Regular Contributor
timestamp: September 29, 2016, 09:28:43 am
content: Quote from: carl_lab on September 29, 2016, 07:48:17 amPatent paper with best description what is it an why need to use:https://www.google.ch/patents/US4777326Quote from the patent:A type of cabling method used in the prior art required the use of a coaxial cable with a resistive center conductor for each signal to be probed. For example, a logic analyzer having 16 probes would require 16 coaxial cables tied together from the logic analyzer to the system under test. This tended to greatly improve the performance of the probing system, since the shielding was greatly improved, bandwidth was increased, and crosstalk was reduced. However, the result was an extremely bulky, costly, and heavy cable, making it difficult for the user to operate with a typical system under test.On short distances up to 20 cm and on frequencies below 100 MHz an ordinary flat cable should to work.GeorgGeorg

author: JFJ
author_rank: Regular Contributor
timestamp: September 29, 2016, 11:37:01 am
content: Quote from: carl_lab on September 28, 2016, 07:29:29 amThe original cable is woven, but its signal and ground conductors are not in twisted pairs. Each signal conductor is separated by two, thinner, ground conductors. This parallel signal/ground conductor arrangement is intended to reduce the capacitive coupling between adjacent channels, to avoid crosstalk. Flat, 80-conductor, Ultra DMA hard drive cables used a similar technique to reduce crosstalk.A twisted pair cable would be of no benefit, because your scope's digital inputs are single ended (all the signal grounds are common). A differential input would be required to reject the common noise pickup of a twisted pair.Quote from: carl_lab on September 28, 2016, 07:29:29 amWhen purchased new, the pod connectors are all the same (unlabeled). A sheet of self adhesive labels is included, so that the user can assign each pod's function.

author: carl_lab
author_rank: Frequent Contributor
timestamp: September 29, 2016, 04:58:24 pm
content: Thanks georgd and JFJ.Quote from: JFJ on September 29, 2016, 11:37:01 amI think, this is correct, but regardless there are twisted pair P-ATA/UDMA HDD cables:AFAIK P-ATA/UDMA is single ended, unlike differential SCPI, so why they use twisted pair cable for P-ATA/UDMA then?

author: timb
author_rank: Super Contributor
timestamp: September 29, 2016, 05:48:27 pm
content: Quote from: carl_lab on September 29, 2016, 04:58:24 pmBecause, it's easier to route these cables inside a computer case, makes things look overall neater and helps with cooling. This happened in the late-90's/early-2000's.Originally, 80 conductor (P)ATA-66 cables were flat, just like their slower 40 conductor ATA-33 counterparts. Case modders would take Exacto knives and cut little slits between every few conductors and then zip tie them together. This led to "round" cables being commercially produced; they're not actually twisted pair in the true sense (though the entire bundle may be twisted together).

author: carl_lab
author_rank: Frequent Contributor
timestamp: September 29, 2016, 06:03:53 pm
content: Quote from: timb on September 29, 2016, 05:48:27 pmI don't think so, this one looks to me like a perfect multiple twisted pair cable.Each pair of wires is twisted separately, not only the whole bundle...Anyway, now I don't think twisted pair cable will have any benefit, because the patent paper's sketches show, the special cable is NOT twisted pair.Another point:The linked patent paper also says:"... is constructed from wire and fabric woven together to form a flat ribbon cable, havingresistance wires for signalsalternating with standard lossless wires for ground to form a lossy transmission line."But standard ribbon cable uses high conductible copper wire... This will cause reflections as mentioned and reduce bandwidth.I don't know, if I need the full bandwidth so using a standard cable maybe OK.Does anybody know, if there will be a signal level problem at lower frequencies, when you use a standard copper ribbon cable instead of the original resistance wire cable?What is the resistance over one signal wire of the original cable?

author: JFJ
author_rank: Regular Contributor
timestamp: September 30, 2016, 02:19:52 pm
content: Quote from: carl_lab on September 29, 2016, 06:03:53 pmThere's only direct access to signal wires at the probe end of an original cable (the plastic shell at the scope end is riveted). The resistance between scope connector and the other end of one signal wire is 190 ohm:Quote from: carl_lab on September 29, 2016, 06:03:53 pmAnother problem with using an 80-conductor PATA cable is that one of signal wires used by the HP54645D, for channel 9 (I think), would be internally shorted to ground, by the connector:It would probably be easier to modify a used woven cable from a different HP Agilent logic analyzer - e.g. a 16510-61601 or 16510-61602 16-channel cable (they usually sell for a tiny fraction of the price of a used 54620-61601 cable).

author: carl_lab
author_rank: Frequent Contributor
timestamp: September 30, 2016, 08:52:34 pm
content: I tried to make a simulation by LTSpicea) using a line resistance of 190 Ohms (original cable)b) using a line resistance of 0 Ohms (standard ribbon cable)Ri calculation: Ri = (100k+370-90.9k-250-190) Ohm = 9030 OhmCi is roughly estimated 10 pF.

author: carl_lab
author_rank: Frequent Contributor
timestamp: September 30, 2016, 09:00:47 pm
content: The amplitude response does not look very flat in both diagrams...I'm sure my model is not absolutely correct (I'm neither a RF specialist nor a LTSpice specialist)...How can I simulate the distributed resistance and distributed capacitance of the woven special cable more realistic?

author: tautech
author_rank: Super Contributor
timestamp: September 30, 2016, 11:38:20 pm
content: IMO you're over thinking it.Digital channels probes do not offer the same response and accuracy as a analogue scope probe or need to.Keep it as simple as possible and give a DIY probe a try.In a real use situation you're only looking at timing correlations between channels and anindicationof amplitude.Even if decoding waveforms can look gawd awful and the scope will still decode.Real bus line or logic performance is best left to a normal or active scope probe.

author: timb
author_rank: Super Contributor
timestamp: October 01, 2016, 09:42:36 am
content: Quote from: carl_lab on September 29, 2016, 06:03:53 pmThe particular cable in that picture *may* use twisted pair, but there's no electrical benefit to it, since the signaling isn't differential. The cable in your picture also has a copper-braided shield that doesn't even appear to be connected, so it looks more "X-Treme Modder" BS than just functional.Like I said, originally we would just take flat 80-conductor ribbon IDE cables and cut slits in the ribboning so it could be zip tied (or heat shrunk) into a bundle. It worked absolutely no differently than the original flat cable. This was commonly done from ATA-66 right up to ATA-133 speeds.

author: Someone
author_rank: Super Contributor
timestamp: October 01, 2016, 11:13:29 am
content: Quote from: timb on October 01, 2016, 09:42:36 amTwisted pair still rejects induced noise and improves crosstalk when used with single ended signalling:http://www.ti.com/lit/an/snla164/snla164.pdf

author: carl_lab
author_rank: Frequent Contributor
timestamp: October 01, 2016, 02:35:31 pm
content: Thanks to all!I will simply test different types of cable, when I get the oscilloscope and the "HP Pod Data+Clock" module incl. probe leads.

author: scopeman
author_rank: Frequent Contributor
timestamp: February 22, 2022, 09:57:13 pm
content: Quote from: JFJ on September 30, 2016, 02:19:52 pmI need to make a set of these cables and I ordered a 40 pin woven cable from another logic analyzer.I have a question about the termination method at the pod end of the cable. Are those wires crimped or are they soldered? My guess is that is resistance wire and that the connection is crimped.Thank you,SamW3OHM

author: oPossum
author_rank: Super Contributor
timestamp: February 22, 2022, 10:15:47 pm
content: Soldered to a PCB

author: gslick
author_rank: Frequent Contributor
timestamp: February 22, 2022, 11:35:46 pm
content: Quote from: scopeman on February 22, 2022, 09:57:13 pmIf you picked up a 40-pin to 40-pin woven cable, part number 01650-61607, as would be used on an HP 1650 series logic analyzer, then just use a common 01650-61608 flying lead set on the POD end of the cable. No assembly required.

author: scopeman
author_rank: Frequent Contributor
timestamp: March 02, 2022, 04:17:10 am
content: Thank you for the detailed close up!Sam

author: dazz1
author_rank: Frequent Contributor
timestamp: August 07, 2023, 08:59:53 am
content: HiIt has been a while since the last post here, but I have just purchased a Hewlett Packard 54645D Mixed Signal Oscilloscope in good condition to add to my ancient and small collection of test equipment.Now I'd like to get the digital probes for it. Absolutely no danger of getting a set in my country. The e-bay prices for the HP 54620-61601 probe set are eye watering.The HP 16510-6160x sets are a lot cheaper, but I don't know the pros/cons of these cheaper probes.What are the current options for making/buying suitable digital probes?

author: dazz1
author_rank: Frequent Contributor
timestamp: August 08, 2023, 12:31:16 am
content: HiI may have found the answer to my own question.See this link the the HP Digital Probe Selection Guidehttps://www.keysight.com/us/en/assets/7018-06707/data-sheets/5968-4632.pdf.

author: tautech
author_rank: Super Contributor
timestamp: August 08, 2023, 12:42:00 am
content: Quote from: dazz1 on August 08, 2023, 12:31:16 amYes, linked in post #8 in this thread.Did you miss it ?

author: dazz1
author_rank: Frequent Contributor
timestamp: August 08, 2023, 04:46:56 am
content: Quote from: tautech on August 08, 2023, 12:42:00 amWhen I clicked on the link, I got a DNS error so I had to find the document myself.I tried attaching the document to my post, but the file size exceeded the limit.

author: dazz1
author_rank: Frequent Contributor
timestamp: August 09, 2023, 10:02:31 am
content: HiI read through the HP Digital probe guide and I did not find it that useful.I have found that the proper digital pod is 54620-61601 originally made for the 54620 logic analyser. Very expensive on e-bay.I did a forum search for HP 54645D and went through all of the postings. It looks like the cable 16510-61602 is compatible, but I don't know if it comes with the pods to connect the grabbers.

author: alm
author_rank: Super Contributor
timestamp: August 09, 2023, 02:18:11 pm
content: Quote from: dazz1 on August 09, 2023, 10:02:31 amNo, the cable is just a woven resistive cable similar to the original cable (but connecting to a single 16 channel pod instead of two smaller 8 channel pods). Although of course things may get sold on eBay in all kinds of combinations. The pods used are described on page 47-50 of the document you didn't find useful. Just search for "hp logic analyzer pod" on eBay. Try to find one with all leads and clips included still in its vinyl pouch. The label like pod 1, pod 5 etc doesn't matter, that's just a label.

author: dazz1
author_rank: Frequent Contributor
timestamp: August 09, 2023, 10:15:39 pm
content: Quote from: alm on August 09, 2023, 02:18:11 pmThe problem is that I haven't used a LA since 1986 so I am a little out of date. Narrowing down the options to pg 47-50 helps a lot. The table on pg46 only has one dot for 1650 series.I found a HP reference herehttps://edadocs.software.keysight.com/kkbopen/what-digital-probe-cables-and-accessories-are-available-for-keysight-mixed-signal-oscilloscopes-msos-589743268.html.It says the 01650-61607 cable was useful but I am not certain if these are all compatible with my HP 54546D scope.I did try plugging in a standard hard drive cable but the connectors have one pin plugged, so that doesn't work. I found a seller nbhightech on e-bay that advertises "Agilent HP 10089A Logic Probe with Flying Leads for 54620C". Sort of a semi DIY solution. I assume the little pcbs have the passive terminator components.I have been looking at modules. The module I have only includes RS232 and parallel port. Not that useful these days Ideally I'd like to get the GP-IB & maths module which is desirable but not essential for me. The e-bay buy-now prices rule out that option.I have also looked at options to replace the noisy fan. The 80mm factory fan specs 47cfm which explains why it is so noisy. A low noise Noctua NF-A8 or NF-R8 could be swapped in but their air flow spec is about half. I need to do some further investigation before trying that mod. Maybe I could add some vanes to better guide the air flow over the heat sinks to compensate for the lower gross airflow. It would be worth it to get rid of the fan noise.I have spent a little time finding my way around the user interface. I can understand why these scopes are still so popular. Very easy to use.If there are deficiencies, it is decoding serial protocols and no published circuit diagrams.

author: dazz1
author_rank: Frequent Contributor
timestamp: August 09, 2023, 10:33:04 pm
content: Quote from: alm on August 09, 2023, 02:18:11 pmI tried that search and got a lot of hits on pods but no pouches. I am unsure whether these pods plug straight into the scope, or if there should be a cable between the scope and the pod. Many listings include references to K,M&N clocks. I don't know if that is something I need to worry about.

author: alm
author_rank: Super Contributor
timestamp: August 09, 2023, 11:01:32 pm
content: Quote from: dazz1 on August 09, 2023, 10:15:39 pmThe information that's relevant to you is what they call 40-pin connectors. 90-pin connectors was something that came in the early 2000's for their high-end logic analyzers. Also anything about Mictor and other PCB connectors is irrelevant for you, because those are only helpful if you're designing your own boards with them in it.Quote from: dazz1 on August 09, 2023, 10:15:39 pmSearch for pictures of either the cable or the end that takes the cable (e.g. HP 1650A/B, 1651A/B, 1652A/B, 1653A/B in the case of 01650-61607, and HP 16510A in the case of the 16510-* cables). It should only have one pod connection (so 16-pins), not two pods as many later cables. And the logic analyzer side should look like an IDE cable (40 pins 0.1"). The pod side always looks like that. If 16510-61602 is compatible, then probably so is 16510-61601 (one is shielded and the other is not shielded). From the pictures it looks like 01650-61607 is shorter, and the 16510 cables seem to have an odd right-angle 40 pin connector, so I'd try to find 01650-61607 if possible.QuoteNot all IDE cables have that pin plugged, and you can remove the pin with a sharp objet. It's generally just press fit. But you might miss on a signal or ground connection, and signal integrity won't be the best without twisting and especially without resistive conductors.Quote from: dazz1 on August 09, 2023, 10:33:04 pmNo, you need a cable between the scope and the pod. Ignore the stuff about different clocks, that's only stickers so on logic analyzers with multiple pods you know which pod corresponds to which clock.As for one with all accessories, see for examplethis one. Not sure if that's the cheapest price. It might also help to search for HP/Agilent E5383A or 01650-61608. Something likeThis listing(I have no relation or experience with this seller) might be interesting, since it appears to come with a cable that looks like it might work, although I prefer the latter flat clips to these round clips. You'll have to search for Australian listings on your own, but this might give you an indication on what to search for. Sellers may not always use the correct part numbers since I don't think they are printed on the cables. At least not very obviously. So it might pay to scroll through a bunch of "hp logic analyzer cable" listings.

author: dazz1
author_rank: Frequent Contributor
timestamp: August 10, 2023, 12:55:46 am
content: Quote from: alm on August 09, 2023, 11:01:32 pmI found that listing by myself, but I had no idea if would be compatible or complete.Quote from: alm on August 09, 2023, 11:01:32 pmAt least it has a pouchQuote from: almI turn on World Wide search on e-bay but almost all hits come from the USA.I will keep looking and following searches. I have no urgent need for anything.

author: dazz1
author_rank: Frequent Contributor
timestamp: August 10, 2023, 01:03:53 am
content: HiWhat about this 01650-61608 :https://4gte.com/products/hp-agilent-01650-61608-differential-probe-adapter/Missing the grippers and cable but seems reasonably priced?Edit:Looks like 61608 are actually for differential probes. Probably not what I need.

author: alm
author_rank: Super Contributor
timestamp: August 10, 2023, 07:51:33 am
content: No, it's not differential. That's an error by 4gte. They didn't have differential pods in the 1650 era. See the 90 pins section of the probing for logic analyzers document for part numbers of differential probes and what they look like.The clips are standard though finding 20 good quality ones might not be any cheaper than buying a complete set. Make sure you get all leads and at least a couple ground leads.

author: dazz1
author_rank: Frequent Contributor
timestamp: August 10, 2023, 08:17:20 am
content: Quote from: alm on August 10, 2023, 07:51:33 amIt seems that error spread because I found a couple of references to differential probes with that part number. That sort of error makes it a lot more difficult for me to identify what I need and whether it will work.I am learning far more about probes than I ever wanted too.Quote from: almShipping anything across the USA border is expensive so it make sense for me to buy a complete set as one package rather than multiple purchases. It also makes sense to maximise $/kg because shipping is a dead cost. For that reason I am better to buy the more expensive GPIB/FFT/Memory module than the cheaper GPIB module. At least that is the excuse I tell my wife.What would be really useful is a website app that shows what part is compatible with any other part.I can see that I will just need to be patient.

author: dazz1
author_rank: Frequent Contributor
timestamp: August 10, 2023, 10:48:59 am
content: Quote from: alm on August 10, 2023, 07:51:33 amYou are definitely right.I found some info on the 01650-61608 at this link (which focuses on the 60pin to 40pin cable):https://www.techtravels.org/2022/11/agilent-logic-analyzer-cable-teardown-photos/So if I got a full pod set including grippers etc, I would only need the 40pin cable to connect to my scope, I think

author: dazz1
author_rank: Frequent Contributor
timestamp: August 11, 2023, 10:47:55 am
content: HiOK so clearly patience is not a virtue I possess. I have purchased the e-bay lead set, complete with pouch.It should include the cable, pod, grounding leads and round style TH grippers.https://www.ebay.com/itm/274747226156and I also purchased 15 of the rectangular type grippershttps://www.ebay.com/itm/126008291238I am hoping the combination of the pod HP 01650-61608 plus the cable will be more versatile than the one piece HP 54620-61601 cable/pod made for my scope, and vastly cheaper.Specifically, the cable sans-pod gives the option of making custom probes, using another style of pod, or plugging into a connector on a pcb (for designed-in probing).The lead set comes with the round style grippers, but I think it is worth the cost of buying the smd grippers as well.The cost of the lead set plus extra grippers gives me another capability at a relatively low price. It will take a month or two for delivery so I will let you know if I wasted my $$$ then.I am going to sell my serial/parallel module and watch & wait for a GPIB/math/memory module.