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" <ailer2@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.

Fahnestock clips? > -----Original Message----- > From: time-nuts-bounces@febo.com > [mailto:time-nuts-bounces@febo.com] On Behalf Of Robert Darlington > Sent: Sunday, March 03, 2013 11:04 > To: Discussion of precise time and frequency measurement > Subject: Re: [time-nuts] Don't use cheap cables -- a cautionary tale > > Alligator clips, of course. > > -Bob > > > On Sun, Mar 3, 2013 at 11:50 AM, Henk ten Pierick > <henk@deriesp.demon.nl>wrote: > > > Hi, > > > > The use of double shielded cables does raise the question > to what type of > > connectors to use? > > > > Regards, > > > > Henk > > > > Op 3 mrt. 2013 om 17:30 heeft Jim Lux > <jimlux@earthlink.net> het volgende > > geschreven: > > > > > On 3/3/13 8:00 AM, Kevin Rosenberg wrote: > > >> On Mar 3, 2013, at 7:59 AM, John Ackermann <jra@febo.com> wrote: > > >>> Lesson learned -- use only double-shielded cable in the > oscillator > > rack (and in any RF measurement path) from now on. > > >> > > >> I've learned that lesson as well. John Miles said that RG-58 is > > occasionally referred to as 'soaker hose'. > > > RG-58 (which by the way, is a spec that officially no > longer exists as > > part of MIL-C17-28, ditto for RG-8, RG-213, etc. The > military apparently > > doesn't use PVC insulated wire any more.) comes in myriad > forms all of > > which bear a passing resemblance to each other. (leaving > aside the RG-58A, > > RG-58, RG-58C differences). > > > > > > The term seems to be used for any 50 ohm single shield > coax that's about > > 0.20 inch in diameter with solid polyethylene insulation. > You really need > > to look at the specific model number to know what the > shielding looks like. > > It could be anything from a very loose weave of thin > copper strands to > > something nice and dense. > > > > > > > > > > > > > > > > > > _______________________________________________ > > > 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. > > > _______________________________________________ > 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.

On 3/3/13 1:41 PM, DaveH wrote: > Fahnestock clips? > >> >> >> Alligator clips, of course. But, I looked through the connector catalogs and I didn't see any double shielded Fahnestock OR Alligator clips.. More seriously, you hook both shields to the shield of the connector. Unless you want to get Triax connectors or use Tip/Ring/Sleeve 1/4" or 1/8" phone plugs. They're used for shielded twisted pair kinds of applications as well (MIL-STD-1553B, for instance) and for audio applications.

RG-223 fits with Telegaertner J01000B0608 (Solder), Buerklin 78F201 or Rosenberger 51S107-108N4 (Crimp) (straight plugs BNC) H155 fits with Telegaertner T00100B3300 N Crimp) ... Am 03.03.2013 19:50, schrieb Henk ten Pierick: > Hi, > > The use of double shielded cables does raise the question to what type of connectors to use? > > Regards, > > Henk > > Op 3 mrt. 2013 om 17:30 heeft Jim Lux<jimlux@earthlink.net> het volgende geschreven: > > >> On 3/3/13 8:00 AM, Kevin Rosenberg wrote: >> >>> On Mar 3, 2013, at 7:59 AM, John Ackermann<jra@febo.com> wrote: >>> >>>> Lesson learned -- use only double-shielded cable in the oscillator rack (and in any RF measurement path) from now on. >>>> >>> I've learned that lesson as well. John Miles said that RG-58 is occasionally referred to as 'soaker hose'. >>> >> RG-58 (which by the way, is a spec that officially no longer exists as part of MIL-C17-28, ditto for RG-8, RG-213, etc. The military apparently doesn't use PVC insulated wire any more.) comes in myriad forms all of which bear a passing resemblance to each other. (leaving aside the RG-58A, RG-58, RG-58C differences). >> >> The term seems to be used for any 50 ohm single shield coax that's about 0.20 inch in diameter with solid polyethylene insulation. You really need to look at the specific model number to know what the shielding looks like. It could be anything from a very loose weave of thin copper strands to something nice and dense. >> >> >> >> >> >> _______________________________________________ >> 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. > > >

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" <ailer2@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