Oscilloscope BNC mating cycle ratings ?

[nurbster]

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.

[001]

What do You mean?
Your scope is low bandwith and high imput impedance device
So any connector will be fine

[I_Code_4_Hugs]

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/2641487

Another exmple, Cinch Vitelec, also states 500 cycles:

https://www.digikey.com/product-detail/en/cinch-connectivity-solutions-vitelec/VBM211-75/1427-1048-ND/4430345

Is that what you're looking for?

[Mr. Scram]

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/2641487

Another exmple, Cinch Vitelec, also states 500 cycles:

https://www.digikey.com/product-detail/en/cinch-connectivity-solutions-vitelec/VBM211-75/1427-1048-ND/4430345

Is that what you're looking for?

That's actually surprisingly little.

[nurbster]

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.

[BillB]

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.

Yeah, 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)    

[Performa01]

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.

Yeah, 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)    

Protection caps don't have any contacts at all, so putting them on/off isn't a mating cycle

[BillB]

Protection caps don't have any contacts at all, so putting them on/off isn't a mating cycle

These do:

[DimitriP]

(dust cap off, probe lead on, probe lead off, dust cap on

Sounds like a lot of work. I leave the probe plugged in

[Mr. Scram]

These do:

Hooking those up definitely counts as a cycle.

[glarsson]

These do:

They 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.

[BillB]

(dust cap off, probe lead on, probe lead off, dust cap on

Sounds like a lot of work. I leave the probe plugged in

It is. 

Knowing that my BNC connections are protected and dust-free allows me to sleep at night.

[Bob Sava]

Only 500 mating cycles?  This makes me wonder if 3 year scope warranty covers BNC connectors.

[metrologist]

What constitutes a failure? These connectors are rated to some performance up to 1GHz (0.2dB IL).

[thm_w]

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.html
https://www.digikey.ca/product-detail/en/cinch-connectivity-solutions-aim-cambridge/CP-AD503/CP-AD503-ND/698061
Or 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.

[PixieDust]

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!

[S57UUU]

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

[vk6zgo]

Only 500 mating cycles?  This makes me wonder if 3 year scope warranty covers BNC connectors.

Professional 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.

[jonpaul]

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

[BillyO]

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.

[nctnico]

Only 500 mating cycles?  This makes me wonder if 3 year scope warranty covers BNC connectors.

Professional BNC connectors are more likely to have "mating cycles" in the 10s, or even 100s of thousands.

Nope. 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.pdf

If you care about mating cycles, use a sacrificial pin safer connector.

[TimFox]

"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.

[Fungus]

Wow! I had no idea these things succumb to mating cycles.

Everything has a specified number of cycles. Absolutely everything.

(and it's usually much lower than you'd imagine...)

[BillyO]

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?

[james_s]

Only 500 mating cycles?  This makes me wonder if 3 year scope warranty covers BNC connectors.

Have 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.