Oscilloscope BNC mating cycle ratings ? - Page 1
Forum section: electronics / testgear

author: nurbster
author_rank: Contributor
timestamp: April 22, 2018, 11:43:17 pm
content: Hi forum. I recently purchased a USB scope ( PicoScope 4444 ) which utilizes D-sub instead of BNC connectors. I inquired with manufacturer if they could provide me with contact type ( i.e. machined or stamp & formed ), plating and mating cycle rating information for the D-sub connector as used in this model. Their answer was the information was "proprietary" although I think they really meant confidential as I don't think there can be anything proprietary about a right-angle surface mount D-sub. Do oscilloscope manufacturers typically publish such data or are connector manufacturers known such that rating information can be obtained ? Can anybody speak to typical ratings of BNC connectors used in oscilloscopes ?Thank you.

author: 001
author_rank: Super Contributor
timestamp: April 23, 2018, 09:31:07 am
content: What do You mean?Your scope is low bandwith and high imput impedance deviceSo any connector will be fine

author: I_Code_4_Hugs
author_rank: Newbie
timestamp: April 23, 2018, 12:35:12 pm
content: Just one example for an Amphenol part says 500 mating cycles:https://www.digikey.com/product-detail/en/amphenol-rf-division/031-5493-1010/ARF2060-ND/2641487Another exmple, Cinch Vitelec, also states 500 cycles:https://www.digikey.com/product-detail/en/cinch-connectivity-solutions-vitelec/VBM211-75/1427-1048-ND/4430345Is that what you're looking for?

author: Mr. Scram
author_rank: Super Contributor
timestamp: April 23, 2018, 01:36:25 pm
content: Quote from: I_Code_4_Hugs on April 23, 2018, 12:35:12 pmThat's actually surprisingly little.

author: nurbster
author_rank: Contributor
timestamp: April 23, 2018, 04:16:09 pm
content: Thanks for replies. Ratings are typically much lower than realized cycles. A rating of 500 does suprise me though as I was thinking BNC connectors as used on scopes would be minimum rating of 1000 and more likely 3000.

author: BillB
author_rank: Unknown
timestamp: April 23, 2018, 04:29:18 pm
content: Quote from: nurbster on April 23, 2018, 04:16:09 pmYeah, I just bought a little bag of BNC protectors/caps because OCD. Now, I'm worried that I'll just be cutting the life of my BNCs to a third. (dust cap off, probe lead on, probe lead off, dust cap on)

author: Performa01
author_rank: Super Contributor
timestamp: April 23, 2018, 10:49:50 pm
content: Quote from: BillB on April 23, 2018, 04:29:18 pmProtection caps don't have any contacts at all, so putting them on/off isn't a mating cycle

author: BillB
author_rank: Unknown
timestamp: April 24, 2018, 01:14:15 am
content: Quote from: Performa01 on April 23, 2018, 10:49:50 pmThese do:

author: DimitriP
author_rank: Super Contributor
timestamp: April 24, 2018, 05:20:53 am
content: QuoteSounds like a lot of work. I leave the probe plugged in

author: Mr. Scram
author_rank: Super Contributor
timestamp: April 24, 2018, 08:47:12 am
content: Quote from: BillB on April 24, 2018, 01:14:15 amHooking those up definitely counts as a cycle.

author: glarsson
author_rank: Frequent Contributor
timestamp: April 24, 2018, 10:34:39 am
content: Quote from: BillB on April 24, 2018, 01:14:15 amThey look identical to the ones I have. The pin is simply screwed into a rubber disc and can easily be removed. Just unscrew the pin using a suitable wet of pliers.I keep a few with pins if I do want to short the input.

author: BillB
author_rank: Unknown
timestamp: April 24, 2018, 04:02:10 pm
content: Quote from: DimitriP on April 24, 2018, 05:20:53 amIt is.Knowing that my BNC connections are protected and dust-free allows me to sleep at night.

author: Bob Sava
author_rank: Regular Contributor
timestamp: April 24, 2018, 04:34:50 pm
content: Only 500 mating cycles? This makes me wonder if 3 year scope warranty covers BNC connectors.

author: metrologist
author_rank: Super Contributor
timestamp: April 24, 2018, 05:03:44 pm
content: What constitutes a failure? These connectors are rated to some performance up to 1GHz (0.2dB IL).

author: thm_w
author_rank: Super Contributor
timestamp: April 24, 2018, 09:43:40 pm
content: If you are paranoid about life then put a short extension on it.For BNC something like this (check it first):https://www.aliexpress.com/item/Pro-Electrical-Accessories-BNC-Male-to-BNC-Female-Jack-in-Series-Right-Angle-RF-Adapter-Connector/32815909617.htmlhttps://www.digikey.ca/product-detail/en/cinch-connectivity-solutions-aim-cambridge/CP-AD503/CP-AD503-ND/698061Or a straight through version.500 rated mating cycles does not mean it will fail after being used 500 times. It simply means they don't guarantee it to meet spec anymore.I've used a 200 cycle rated connector over 10,000 times and its still functional for what I use it for. Of course it may be well out of spec in terms of contact resistance at this point.

author: PixieDust
author_rank: Frequent Contributor
timestamp: December 10, 2022, 12:25:11 pm
content: Wow! I had no idea these things succumb to mating cycles. I thought you could plug you probes in as many times as you want!

author: S57UUU
author_rank: Regular Contributor
timestamp: December 10, 2022, 01:29:11 pm
content: Probably you can. I'm an ee with 40 years practice, and newer saw a BNC fail (save mechanical abuse), neither at work nor at my home lab, where I went through a lot of ancient scopes, way past their warranty period.Note than even when new, BNCs are not considered stable phase connections - but they were never meant to be microwave connectors.As someone already wrote, for low frequencies (<100MHz) and high impedance, you do not need microwave class connections.Just treat them gently, and keep them clean, and don't count the connections. :-)Maybe in some high volume production line, where thy are connected 100 times per day, 250 days per year, they will eventually degrade (gold plating scratched off), so the manufacturer is just covering his back.Marko Cebokli

author: vk6zgo
author_rank: Super Contributor
timestamp: December 10, 2022, 01:56:43 pm
content: Quote from: Bob Sava on April 24, 2018, 04:34:50 pmProfessional BNC connectors are more likely to have "mating cycles" in the 10s, or even 100s of thousands.The cruddy little things shown in the links earlier may well have vanishingly small mating cycles.

author: jonpaul
author_rank: Super Contributor
timestamp: December 10, 2022, 02:31:33 pm
content: Check Amphenol BNC types and specs.Since, 1960s as an EE, never had a BNC fail on scope or cable, except when mechanically abused, instrument drop, junk off ebay, etc.But we use Tektronix, Yokogawa and Hameg scopes, no experience with recent crop of Chinese, nor the Picos.J

author: BillyO
author_rank: Super Contributor
timestamp: December 10, 2022, 04:43:25 pm
content: The way BNC connectors are designed the contacts are aligned before they connect. They should last a good long time. My over 40 year old Tek 465 is still going strong and a 12 year old UNI-T has had no issues either despite having probes connected and disconnect nearly every day.

author: nctnico
author_rank: Super Contributor
timestamp: December 10, 2022, 05:09:46 pm
content: Quote from: vk6zgo on December 10, 2022, 01:56:43 pmNope. 500 mating cycles is pretty standard for BNC connectors. Even the very expensive ones.For example this 88 euro one from Huber & Suhner:https://www.farnell.com/datasheets/2607930.pdfIf you care about mating cycles, use a sacrificial pin safer connector.

author: TimFox
author_rank: Super Contributor
timestamp: December 10, 2022, 05:29:45 pm
content: "500 min" is also the formal specification for "normal price" BNCs from Amphenol.Probably a military specification.I've never had one fail at the interface with another BNC.

author: Fungus
author_rank: Super Contributor
timestamp: December 10, 2022, 07:09:27 pm
content: Quote from: PixieDust on December 10, 2022, 12:25:11 pmEverythinghas a specified number of cycles. Absolutely everything.(and it's usually much lower than you'd imagine...)

author: BillyO
author_rank: Super Contributor
timestamp: December 10, 2022, 07:28:59 pm
content: Yeah, unfortunately we often get "boiler plate/industry standard" specs. Specifications that have always been good enough and always expected and have been accepted for decades. I'm sure if they actually went to the trouble of testing these beyond the good old familiar 500 cycles, they'd probably go much, much further. But they won't voluntarily publish higher specs unless they are forced into it (by demand) otherwise they'll be on the hook to honor them.I wonder who first presented the 500 cycle spec?

author: james_s
author_rank: Super Contributor
timestamp: December 10, 2022, 07:36:30 pm
content: Quote from: Bob Sava on April 24, 2018, 04:34:50 pmHave you ever worn one out? I haven't, and I have multiple scopes that are over 30 years old. A portable scope that is used in the field and gets packed and unpacked every day could have an issue but in most cases I wouldn't be worried about it.I'd expect most of them to last a lot longer than the minimum rating of mating cycles, especially if you handle them gently.

author: nctnico
author_rank: Super Contributor
timestamp: December 10, 2022, 09:09:43 pm
content: Quote from: james_s on December 10, 2022, 07:36:30 pmI have had flaky BNCs on some test equipment. So yes, it is possible to wear BNCs. But age doesn't matter; the number of mating cycles does. I make it a habit of not disconnecting probes when I don't have to.I've also experienced worn PCI slots (which are typically rated for 30 mating cycles or so) which meant throwing the motherboard away (this was in a PC used for testing boards so it did see quite a lot of mating cycles).

author: TheSteve
author_rank: Unknown
timestamp: December 10, 2022, 09:28:34 pm
content: I've seen worn out BNC's on several items over the years. The locking posts were half gone. No idea how many cycles it took for that to happen. I do know I push inwards when I turn a BNC to prevent too much pressure on the pins.