Hey: Don't forget that the cable itself is noisy when moved. Especially Teflon insulation. Don On 2021-08-30 06:51, Bob kb8tq wrote: > 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 >> <darren@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-leave@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-leave@lists.febo.com > To unsubscribe, go to and follow the instructions there. ------------ The whole world is a straight man. ---------------------- Dr. Don Latham AJ7LL PO Box 404, Frenchtown, MT, 59834 VOX: 406-626-4304