Testing Fake BNC Connectors - Page 1
Forum section: electronics / rf-microwave

author: msngupta
author_rank: Contributor
timestamp: May 16, 2017, 02:54:24 am
content: Hi,One of my colleagues purchased few panel mount BNC connectors from EBAY few days ago. While I was trying to use it for one of my circuits, I found that the central/signal pin is made of plastic and it breaks very easily. Its just coated with some golden conducting substance (Check the image of connector with broken central pin. It was very shocking to find that they made it out of some kind of plastic.Though I decided to discard those batch of connectors, I am worried about some other BNC/SMA connectors we have that were procured from unauthenticated sources. Though some of them I checked didn't have the plastic signal pin, but on checking with a magnet they were magnetic (while a amphenol ones were not). Even few BNC cables we had were having magnetic outer core. I don't know if this is a problem to worry about.So, my question is what kind of (torture)tests should I make on general connectors/gender changers/cabels etc., to make sure that they work properly. How can I find they fit my specifications like having 50ohm impedance etc. My extreme working conditions would be have currents from few milliamps to few Amps with signals varying from sensitive DC signals to few hundreds of MHz. Any advice (other than asking to through away all of them) will be really helpful.Thanks,Sainath.

author: edpalmer42
author_rank: Super Contributor
timestamp: May 16, 2017, 04:05:18 am
content: Are you sure that the center contact was plastic? If you touched it with a soldering iron it would either burn or melt. Maybe it was just some really cheap cast metal with pretty plating over it. Can you do a continuity test on the dark, inner part?Ed

author: electr_peter
author_rank: Unknown
timestamp: May 16, 2017, 08:24:38 pm
content: Center pin does look very suspicious. I have never seen this in electronics but have seen similar decorative plastic pieces.Could you make another better close-up photo? What does the front connector look like? Could you carefully disassemble the connector to confirm if and which pieces are plastic?

author: ChristofferB
author_rank: Frequent Contributor
timestamp: May 16, 2017, 10:18:21 pm
content: I'm not sure I'm buying the plastic thing either. Metal plating plastic is a pretty advanced operation, and would likely be more expensive than just making a center pin out of compressed tuna can or something. Plastic or not, it's probably not a mil-spec connector either wayAs to torture tests, you could basically just go though the datasheet and try exceeding all the ratings and see how it performs. obviously, stuff like plastic (and apparantly metal) brittleness could probably be assayed a bit unscientifically with a hammer

author: CJay
author_rank: Super Contributor
timestamp: May 17, 2017, 05:19:46 am
content: Looks like diecast pot metal that's been plated with something.

author: charliedelta
author_rank: Regular Contributor
timestamp: June 11, 2017, 06:40:19 am
content: Then when you get time test the horrible Ebay SMA connectors. Its like filing metal when you screw them up they so bad.Then the female SMA PCB right angle sockets that pulls the whole threaded SMA socket out of the holder when you tighten the connector.Their BNC's are bad but the Chinese SMA connectors are like a nightmare.I would not screw any Chinese SMA or N connector into any quality piece of test equipment or CAL Kit!

author: dmills
author_rank: Super Contributor
timestamp: June 11, 2017, 11:54:26 am
content: Concur, MA-com, Huber-Schurner and Rosenburger among others make the real deal and can be had on ebay as surplus for reasonable money, while I am sure they are mostly made in China there is a difference.Having gotten a knock off XLR stuck in some very expensive test gear, I have sworn off buying connectors based on 'cheap'.73 Dan.