Mating Cycles - are your connectors worn out ? - Page 1
Forum section: electronics / general

author: bilko
author_rank: Frequent Contributor
timestamp: April 24, 2011, 12:50:39 am
content: Anybody care to comment on mating cycles for connectors. Most manufacturers specify how many mating cycles their connector can handle before there is a degradation in performance.Is changing BNC sockets on test equipment a maintenance issue ?See spec below for a typical BNC socket manufactured by TycoTYCO ELECTRONICS / GREENPARManufacturer Part No:1-1337494-0RoHS Compliance : RoHS Compliant YesDescription* SOCKET, BNC INS PCB R/A 50R SHEILDED* Coaxial Termination:Solder* Connector Mounting:PCB* Connector Type:BNC, Coaxial* Contact Material:Brass* Contact Plating:Gold* Frequency Max:4GHz* Impedance:50ohm* Body Plating:Nickel* Body Style:Right Angle Jack* Connector Mounting Orientation:PC Board* Connector Type:BNC, Coaxial* Contact Material:Brass* Contact Plating:Gold* Contact Resistance:1.5mohm* Insulation Resistance:5000Mohm* Insulator Material:* Mounting Type:PC Board*No. of Mating Cycles:50* Operating Temperature Max:+85°C* Operating Temperature Min:-55°C* Termination Method:Solder* Withstand Voltage:1500V* Working Voltage:500V* Mounting Orientation:Right Angle* Operating Frequency Max:4GHz* Plug Body Material:Zinc

author: qno
author_rank: Frequent Contributor
timestamp: April 24, 2011, 08:59:11 am
content: This is due to the gold plating.Tinned connectors are much higher although not infinite.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: April 24, 2011, 10:22:45 am
content: Also note it's specced to 4GHz - the 50 cycles is what they guarantee the high-frequency performance for.One would hope that in decent test gear they use connectors with a higher mating-cycle spec. They also tend to use different connectors for high frequency stuff over about 1GHz.

author: Fraser
author_rank: Super Contributor
timestamp: April 24, 2011, 01:06:42 pm
content: When working with calibrated HP and similar RF test gear for professional use it is very important that the calibration be maintained right up to the connectors (and beyond). The manufacturer is being very clear in their warning that after a certain number of connect/disconnect cycles, the RF connection is worn and should be considered a weak point in the calibration chain.Interestingly, the more professional and expensive a piece of RF test equipment is, the less mating cycles you are likely to see stated. This reflects the manufacturers accute awareness of the vulnerability caused by mechanical connectors and risk of calibration errors due to connector losses.In many professional RF labs you will see equipment fitted with sacraficial connectors that are scrapped after a certain number of mating cycles. The sacraficial connectors look like some sort of extension as they are male to female. Quality sacraficial connectors are expensive but cheaper than replacing the main RF connector on a piece of expensive RF test kit.The SMA connector is commonly used as a constant impedance mechanical coupling and the small size of the pin and screw fitting makes them quite fragile and liable to relatively rapid wear if regularly uncoupled and recoupled.In a less damanding lab or hobby environment users can normally consider the connector life to be very long and of no geat importance unless damage is visable. That is the big difference between professional RF test & calibration labs and the simple production or repair workshop environments.A warning... if you buy a cheap Far Eastern produced SMA connector it will likely disappoint if you require very high performance. It is not unusual to spend GBP25 to GBP50 on a professional SMA connector for 18GHz. Far Eastern SMA connectors are fine for non demanding work below 5GHz but watch out for the gold plating peeling off of the SMA centre pin as that leaves swarf in you expensive test equipments RF socket ! Been there done that

author: tekfan
author_rank: Frequent Contributor
timestamp: April 24, 2011, 01:43:06 pm
content: Up to 1GHz there is no problem with BNC's even after 1000+ cycles. I stored a fast risetime square wave on an (25 year old) 1GHz scope when i got it and it still looks exaclty the same after more than 1000 cycles. Who knows how many times the BNC's were plugged and unplugged before. The scope still meets the rise time spec of 1GHzFor anything above 4GHz I would also use SMA's.

author: Unknown
author_rank: Unknown
timestamp: April 24, 2011, 02:20:22 pm
content: SMA has better high-frequency performance than BNC, but I wouldn't consider it more durable.

author: Zad
author_rank: Super Contributor
timestamp: April 25, 2011, 03:45:11 pm
content: TNC connectors tend to be more robust than their bayonet counterpart, although obviously they are inherently slower to use. N connectors should be even more robust still.