Noise bursts come from the rubbing of the shield on the dielectric. Try putting some rg58 on the input of a guitar amp :-) Even "low-noise" rg58 type coax is noisy; it has some graphite on the dielectric supposedly to suppress the triboelectric (rubbing) noise. You might think Teflon would be quiet, but not so. Don
John Ackermann > I've previously encountered noise from mechanical movement of BNCs. You > can definitely see noise bursts when you move a BNC cable around. > Replacing TNC-BNC adapters and BNC-BNC cables at the analyzer with real > TNC to SMA cables, and SMA to BNC adapters on the far end when > necessary, solved a lot of those problems. > > But this was the first time I've seen a continuous beat-note type of > interference that I could trace to the cabling. > > As a follow-on topic -- I wonder if the leakage problem would also be > significant in a PPS distribution/measurement system (vs 5 or 10 MHz > RF). I'd think that working with pulses and using a defined trigger > level might mitigate that, but as I contemplate my rat's nest of PPS > cabling I wonder if there could still be problems. > > John > ---- > Alan Melia said the following on 03/03/2013 03:36 PM: >> Some of the older synchronised signal generators (2-box systems) e.g >> Marconi, used TNC connectors with solid coax where signal leakage was >> likely to be a problem. >> Alan G3NYK >> ----- Original Message ----- From: "Volker Esper" <ail...@t-online.de> >> To: <time-nuts@febo.com> >> Sent: Sunday, March 03, 2013 6:49 PM >> Subject: Re: [time-nuts] Don't use cheap cables -- a cautionary tale >> >> >>> >>> Yes, we all have to learn that lesson... >>> >>> At the time I use bedea RG-223 and Belden H155 with soldered and >>> crimped Telegaertner BNC connectors as general purpose cable (up to 2 >>> GHz). Above that frequency I wouldn't use BNC. If you simply connect >>> your tracking generator with the spectrum analyzer by using such a >>> BNC >>> cable there's not one that is absolutely stable when stressing the >>> connector. I tried several manufacturers, HP, Suhner, Radiall, >>> Rosenberger, it's always the same. >>> >>> To make precise measurements I prefer screwed connectors like N or >>> SMA. >>> >>> Volker >> >> _______________________________________________ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > -- "Neither the voice of authority nor the weight of reason and argument are as significant as experiment, for thence comes quiet to the mind." De Erroribus Medicorum, R. Bacon, 13th century. "If you don't know what it is, don't poke it." Ghost in the Shell Dr. Don Latham AJ7LL Six Mile Systems LLP 17850 Six Mile Road POB 134 Huson, MT, 59846 VOX 406-626-4304 www.lightningforensics.com www.sixmilesystems.com _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
