I have used BNC connectors for many years and for many purposes without problems until now. The connectors I use are good quality Amphenol either nickel or silver plated. One of my AM transmitters uses a BNC for the antenna connection and I noticed that the final stage current was erratic and would change if I wiggled the connector. The panel mount female connector was obtained from a surplus electronics seller and is of unknown lineage and I suspect that the plating is either inferior or perhaps some cheap material such as tin. A squirt of contact cleaner fixed this problem but if it happens again then the connector will be replaced.
Quite often I have experienced audio distortion and erratic levels which were traced to the miserable RCA phono pin connectors and jacks and cleaning these with contact cleaner really helps. I mention this so perhaps you can avoid wasting a lot of time tracking down distortion or level problems when many times the cause and cure is quite simple.
I use DeoxIT D5 which I have found to work better than other brands which I have used. A small can is $18 but sometimes time and aggravation saved costs a bit more.
Neil
I have had numerous issues with BNC connector issues even when I had a police scanner and worse from FM transmitters that use BNC connectors. Seriously I'd rather a PL-259, TNC, or even F connectors and it would be 75 Ohms but a 75 ohm rubber duck is hard to find for an FM Transmitter however with a 75 ohm connector you could do the poor mans FM antenna and that would be a wire T dipole or even rabbit ears that does not have an amp in them which you could buy for $7 at Radio Shack or Wall Mart. I learned really quick when I had an FM Transmitter in Michigan that BNC's are not always stable and can cause your transmitter to burn out from transmitting without a good antenna connection.
I still have some crippled ITC Tape Recorders, fantastically peculiar decks marketed right at the end of the age of analog tape, probably designed by a committee.
Half of the committee overbuilt with aluminum plates way thicker than necessary and rewind motors powerful enough to fly an airplane.
The other half of the committee went super-cheap with all kinds of dainty plastic or under-rated parts that breakdown.
Point is, they used BNC cables to connect from the heads to the playback amps and recording amps. Those cables all went bad, I'm not sure why.
That's why better connectors and audio cables are gold plated....it's not a gimmic. Nickel tarnishes and after awhile you get what radio8z has happen to him...same as bad connection and needs to be cleaned with alcohol.
Gold doesn't ever oxidize or tarnish and the electrical contact is never lost.
Mark
Oh I agree totally. But I've never seen a gold TNC connector. Especially the ones you find at Radio Shack. I'm almost sure too that the rubber duck antenna's that have TNC connectors are not gold plated. I've seen very F connecors that way either. Its hard to get good gold plated connectors for Transmitters. Its why I think many of them fail because of poor antenna connectors.