Hi This sort of trouble with BNC’s has been going on a lot longer than they have been coming in from China. A lot of folks use them *way* past the point they should. They do indeed wear out. They also come loose on the cable.
We went a bit nuts “killing off” all the BNC cables in the area back in …errr … 1976. The result was a significant bump in the supples budget that month and the elimination of a whole bunch of problems on a number of tests. Back in that era Motorola could afford to buy / fab a few cables. Did the saved labor hours justify the expense? We claimed it did……It most certainly made life easier. Bob > On Aug 30, 2021, at 1:26 AM, Darren Freeman <dar...@freemaninstruments.com> > wrote: > > On Sun, 2021-08-29 at 09:21 -0500, Dana Whitlow wrote: >> I believe that a significant problem in my case was not leakage >> through the >> shield, but >> rather common-mode currents on the cable. My experiences were with >> RG-6 >> style cable, > > Chiming in with a maybe tangential issue. > > I had some really unreliable strange behaviour in my lab, and I traced > it to some low quality BNC crimp plugs. The noise at my receiver would > fluctuate by tens of dB, as I wiggled the connector. With a good > connector, it's dead quiet all of the time. > > My conclusion was that the outer conductor was not making contact when > the plug was mated with a socket, and so outer currents were flowing > through the spring, and through the part of the plug that you rotate > when locking it to the socket. That adds some impedance, and your > receiver is now also listening to the common-mode current, that should > flow harmlessly to the chassis. > > Visually, you can spot these particular bad plugs from the lack of > slots in the outer conductor. There's no way for it to compress as it's > mated with the socket, so they are under-sized instead. They often feel > loose. It may work sometimes, but not with all sockets, and only if > gravity is pulling on the cable just right. > > All of the ones I've received from China have been like this. They went > in the bin. The ones from Jaycar, my local electronics shop, appear to > be identical. I used them anyway, because I was travelling a lot. Since > that time, I have been cutting them off my cables, hopefully I've > gotten them all. > > It's been a sad lesson. Time and money down the drain, but at least I > worked out what was going on in the end. > > Maybe someone else is struggling with this issue? Try wiggling all the > connectors :) > > Have fun, > Darren > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an > email to time-nuts-le...@lists.febo.com > To unsubscribe, go to and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.