I use some Pomonas also and I think they are single shielded except the Y which is double shielded. This may explain some artifacts I have in my house reference. Great Thread Thomas Knox
> To: time-nuts@febo.com > From: johncr...@aol.com > Date: Sun, 3 Mar 2013 14:08:15 -0500 > Subject: Re: [time-nuts] Don't use cheap cables -- a cautionary tale > > I could not agree more, having been burned once or twice. > > One batch of "50 Ohm" cables was clearly marked 75 Ohms when received. These > used some form of > relatively high resistance foil shield and a drain wire for the outer > conductor. The high resistance permitted > a ground loop with hum on my 10 MHz reference thus FMing my signal generator. > > A couple of things to note: > > Measure the DC resistance between the connector bodies it should be way less > than 1 Ohm, perhaps > 0.1 ohm above what you see with the probes shorted. > > The previous regarding RG-58 apply unless the cable is labeled with a > manufacturers part number and that is stated in the vendors spec - > > Such as > > BELDEN 8262 RG-58U Coaxial BNC M/M Patch Cable 10FT. > > RG58 C/U MIL C17 50 OHMS stamped on the cable. > > These were from - Digital Connections - cablesellforl...@yahoo.com and > purchased via eBay. The price was very reasonable. > > Testing with a HP ANA showed very low VSWR and the expected insertion loss up > to 1 GHz. Shield resistance was very low, as expected. I have used these in > lengths from 3 ft to 20 ft with no difficulty. > > The key here is the Belden part number in the vendors ad that can be checked > to see what you are getting. The MIL SPEC and RG58 etc was stamped on the > cables when received. > > For outstanding performance use RG-223 which is slightly larger than RG-58 > and is a 50 Ohm cable > having a very dense double sliver plated braid shield. > > You can buy these made up for a small fortune or buy an odd lot of RG-223 on > eBay and make your own. Pasternak has the connectors with the appropriate > diameter nuts and collars. The connectors for Rg-58 > are had to make work on RG-223. Connectors for Type N and SMA are also > available. > > Installing clamp style connectors on RG-223 requires a certain amount of > passion (and a stainless steel welders tooth brush to comb the braid) but > hey, no pain no gain. > > -73 john k6iql > > > > > > > -----Original Message----- > From: time-nuts-request <time-nuts-requ...@febo.com> > To: time-nuts <time-nuts@febo.com> > Sent: Sun, Mar 3, 2013 11:00 am > Subject: time-nuts Digest, Vol 104, Issue 13 > > > Send time-nuts mailing list submissions to > time-nuts@febo.com > > To subscribe or unsubscribe via the World Wide Web, visit > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > or, via email, send a message with subject or body 'help' to > time-nuts-requ...@febo.com > > You can reach the person managing the list at > time-nuts-ow...@febo.com > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of time-nuts digest..." > > > Today's Topics: > > 1. Re: Don't use cheap cables -- a cautionary tale (Bob Camp) > 2. Re: webcam app to watch for and time stamp changes > (Magnus Danielson) > 3. Re: Don't use cheap cables -- a cautionary tale (John Ackermann) > 4. Re: Don't use cheap cables -- a cautionary tale (Kevin Rosenberg) > 5. Re: Don't use cheap cables -- a cautionary tale (Bob Camp) > 6. Re: Don't use cheap cables -- a cautionary tale (Jim Lux) > 7. Re: webcam app to watch for and time stamp changes (cfo) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Sun, 3 Mar 2013 10:10:38 -0500 > From: Bob Camp <li...@rtty.us> > To: Discussion of precise time and frequency measurement > <time-nuts@febo.com> > Subject: Re: [time-nuts] Don't use cheap cables -- a cautionary tale > Message-ID: <335213bf-bbf3-44bd-9a7a-0bd481028...@rtty.us> > Content-Type: text/plain; charset=iso-8859-1 > > Hi > > By any chance is the connector a BNC? They have been known to create similar > looking issues. > > Bob > > On Mar 3, 2013, at 9:59 AM, John Ackermann <j...@febo.com> wrote: > > > I was measuring two OCXO and was getting some quite unusual results -- a > symmetrical frequency cycling of several more than 1e11 p-p, with a period of > around 15 seconds. > > > > I removed an RG-58 3 foot jumper cable that fed 5 MHz from the rear panel > > of > another OCXO to a patch panel (where it was terminated in 50 ohms), and the > noise quieted right down. See the attached frequency plot. > > > > The other OXCO had a similar jumper cable in the path, and although the two > cables were not parallel to each other for any significant distance, there > was > still enough signal radiation and pickup to cause a nasty problem. > > > > Lesson learned -- use only double-shielded cable in the oscillator rack > > (and > in any RF measurement path) from now on. > > > > John > > <austron-fts-beat-note.png>_______________________________________________ > > 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. > > > > ------------------------------ > > Message: 2 > Date: Sun, 03 Mar 2013 16:29:15 +0100 > From: Magnus Danielson <mag...@rubidium.dyndns.org> > To: time-nuts@febo.com > Subject: Re: [time-nuts] webcam app to watch for and time stamp > changes > Message-ID: <51336c4b.4030...@rubidium.dyndns.org> > Content-Type: text/plain; charset=ISO-8859-1; format=flowed > > On 03/03/2013 03:46 PM, Jim Lux wrote: > > On 3/3/13 1:00 AM, Poul-Henning Kamp wrote: > >> Content-Type: text/plain; charset=ISO-8859-1 > >> -------- > >> In message <657D7F7CC03849419A2A90752E6A60A6@pc52>, "Tom Van Baak" > >> writes: > >> > >>> When playing with watches a while ago I tried to pick up any 32 > >>> kHz signal but failed. Those with 1 Hz stepper motors were easy, > >>> but LED or LCD displays were too electro/magnetic/acoustic quiet > >>> for me to ever detect anything. > >> > >> Most LCD and LED clocks have a shielding metal-coating on the front > >> glass, exactly to eliminate all EMI/EMC issues. > >> > > > > Yes, but perhaps there's enough leakage to make this work. After all, > > the EMI requirement (assuming it's running at 32 kHz) isn't particularly > > stringent and because the fob is small, the radiated field at any > > distance is going to very small. OTOH, I can put a probe or coil right > > on or around the fob. > > > > I'll let you all know what I detect when I try it tomorrow. > > An electrostatic shield will not contain the H-field from the shifting > currents. > > Cheers, > Magnus > > > ------------------------------ > > Message: 3 > Date: Sun, 03 Mar 2013 10:46:10 -0500 > From: John Ackermann <j...@febo.com> > To: Discussion of precise time and frequency measurement > <time-nuts@febo.com> > Subject: Re: [time-nuts] Don't use cheap cables -- a cautionary tale > Message-ID: <51337042.4020...@febo.com> > Content-Type: text/plain; charset=ISO-8859-1; format=flowed > > Yup, they are BNC (by necessity). I'm still experimenting but it may be > an ill-fitting connector on the cheap patch cable. Switching to a > better quality cable seems to have solved the problem, one way or the other. > > John > ---- > Bob Camp said the following on 03/03/2013 10:10 AM: > > Hi > > > > By any chance is the connector a BNC? They have been known to create > > similar > looking issues. > > > > Bob > > > > On Mar 3, 2013, at 9:59 AM, John Ackermann <j...@febo.com> wrote: > > > >> I was measuring two OCXO and was getting some quite unusual results -- a > symmetrical frequency cycling of several more than 1e11 p-p, with a period of > around 15 seconds. > >> > >> I removed an RG-58 3 foot jumper cable that fed 5 MHz from the rear panel > >> of > another OCXO to a patch panel (where it was terminated in 50 ohms), and the > noise quieted right down. See the attached frequency plot. > >> > >> The other OXCO had a similar jumper cable in the path, and although the > >> two > cables were not parallel to each other for any significant distance, there > was > still enough signal radiation and pickup to cause a nasty problem. > >> > >> Lesson learned -- use only double-shielded cable in the oscillator rack > >> (and > in any RF measurement path) from now on. > >> > >> John > >> <austron-fts-beat-note.png>_______________________________________________ > >> 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. > > > > > > ------------------------------ > > Message: 4 > Date: Sun, 3 Mar 2013 09:00:03 -0700 > From: Kevin Rosenberg <ke...@rosenberg.net> > To: Discussion of precise time and frequency measurement > <time-nuts@febo.com> > Subject: Re: [time-nuts] Don't use cheap cables -- a cautionary tale > Message-ID: <032c3cb2-5c27-4338-8196-697415f7e...@rosenberg.net> > Content-Type: text/plain; charset=iso-8859-1 > > On Mar 3, 2013, at 7:59 AM, John Ackermann <j...@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'. > > Kevin > > > > ------------------------------ > > Message: 5 > Date: Sun, 3 Mar 2013 11:08:45 -0500 > From: Bob Camp <li...@rtty.us> > To: John Ackermann <j...@febo.com> > Cc: Discussion of precise time and frequency measurement > <time-nuts@febo.com> > Subject: Re: [time-nuts] Don't use cheap cables -- a cautionary tale > Message-ID: <6a29d6e9-b3ba-4e3c-b10b-e91f30816...@rtty.us> > Content-Type: text/plain; charset=windows-1252 > > Hi > > BNC's suffer from shield separation issues and from basic wear out on the > connector it's self. Cheap coax = shield seperation. On the connector its > self > it's either plating or loss of spring in the fingers. The best solution is > to > cut the connector off the cable. That way at least it doesn't mess you up a > second time. Once you get a big enough pile of single ended cables, it's time > to > get out the crimp tool?. > > Bob > > On Mar 3, 2013, at 10:46 AM, John Ackermann <j...@febo.com> wrote: > > > Yup, they are BNC (by necessity). I'm still experimenting but it may be an > ill-fitting connector on the cheap patch cable. Switching to a better > quality > cable seems to have solved the problem, one way or the other. > > > > John > > ---- > > Bob Camp said the following on 03/03/2013 10:10 AM: > >> Hi > >> > >> By any chance is the connector a BNC? They have been known to create > >> similar > looking issues. > >> > >> Bob > >> > >> On Mar 3, 2013, at 9:59 AM, John Ackermann <j...@febo.com> wrote: > >> > >>> I was measuring two OCXO and was getting some quite unusual results -- a > symmetrical frequency cycling of several more than 1e11 p-p, with a period of > around 15 seconds. > >>> > >>> I removed an RG-58 3 foot jumper cable that fed 5 MHz from the rear panel > >>> of > another OCXO to a patch panel (where it was terminated in 50 ohms), and the > noise quieted right down. See the attached frequency plot. > >>> > >>> The other OXCO had a similar jumper cable in the path, and although the > >>> two > cables were not parallel to each other for any significant distance, there > was > still enough signal radiation and pickup to cause a nasty problem. > >>> > >>> Lesson learned -- use only double-shielded cable in the oscillator rack > >>> (and > in any RF measurement path) from now on. > >>> > >>> John > >>> <austron-fts-beat-note.png>_______________________________________________ > >>> 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. > >> > > > > > > ------------------------------ > > Message: 6 > Date: Sun, 03 Mar 2013 08:30:43 -0800 > From: Jim Lux <jim...@earthlink.net> > To: time-nuts@febo.com > Subject: Re: [time-nuts] Don't use cheap cables -- a cautionary tale > Message-ID: <51337ab3.6020...@earthlink.net> > Content-Type: text/plain; charset=ISO-8859-1; format=flowed > > On 3/3/13 8:00 AM, Kevin Rosenberg wrote: > > On Mar 3, 2013, at 7:59 AM, John Ackermann <j...@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. > > > > > > > > ------------------------------ > > Message: 7 > Date: Sun, 3 Mar 2013 16:52:06 +0000 (UTC) > From: cfo <xne...@luna.dyndns.dk> > To: time-nuts@febo.com > Subject: Re: [time-nuts] webcam app to watch for and time stamp > changes > Message-ID: <kgvv3m$ug7$1...@ger.gmane.org> > Content-Type: text/plain; charset=UTF-8 > > On Sat, 02 Mar 2013 11:33:02 -0800, Jim Lux wrote: > > > I am interested in the timing behavior of my RSA fob, which changes > > every 60 seconds. Since I'm not about to open it up and probe inside, I > > was wondering if someone had a clever way, say using a USB web cam, to > > log the changes over a 48 hour period. You'd point the web cam at the > > fob, and it would log the time when the display changes Or one might > > even be able to look at the blinking 1 pps indicator using a light and > > photocell or something.. > > Isn't this "Just what the doctor ordered" > http://smallhacks.wordpress.com/2012/11/11/reading-codes-from-rsa- > secureid-token/ > > CFO > > > > ------------------------------ > > _______________________________________________ > time-nuts mailing list > time-nuts@febo.com > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > End of time-nuts Digest, Vol 104, Issue 13 > ****************************************** > > > _______________________________________________ > 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.
