Andrew Sureflex (FSJ) is a lot more flexible then the LDF4 Healix, which is what you find a lot of on ebay and at hamfests. Here is some 1/4" Sureflex, new: Andrew Type N Male to Type N Male Sureflex Cable 30 feet F1RNA-PNMNM-30-L1 NEW! https://www.ebay.com/itm/173863049072 US $30.00 + $13.02 Shipping. For two pieces shipping goes to $16.33, for three $22.90 You can cut it with a hacksaw, do NOT use wire cutters. Connectors can be installed with just hand tools. If you move the test equipment around it's not very practical, but if it's setup on a bench or in a rack it will work. Robert On 08/29/2021 09:51 AM, Bob kb8tq wrote: > Hi > > Skin depth is what gets you with most coax at 10 MHz, even with the “double > shield” stuff. Hardline with a nice heavy outer would do better. It’s not terribly > practical around the typical lab. Might not be a bad choice for a “burry in the yard” > setup though. With normal cable, the losses from the soil at normal burial > depths make a good shield, that makes dealing with it questionable even there …. > > Bob > >> On Aug 29, 2021, at 9:36 AM, Robert DiRosario <ka3zyx@comcast.net> wrote: >> >> What about double shielded RG-223, or Thinnet ethernet cable? >> Most Thinnet has both a braided shield and a foil wrap. >> >> Robert >> >> On 08/28/2021 08:26 PM, Bob kb8tq wrote: >>> Hi >>> >>> Anything you do that has a bunch of 10 MHz cables running out from here or there >>> will impact your ability to listen to WWV at 10 MHz :) Other than killing all the sources, >>> there is no silver bullet. >>> >>> Bob >>> >>>> On Aug 28, 2021, at 7:57 PM, Dana Whitlow <k8yumdoober@gmail.com> wrote: >>>> >>>> Bob, my own motivation for going to fiber was entirely different. I >>>> simply wanted to >>>> run 10 MHz all over the place from reference sources in disparate >>>> locations in the >>>> house, and I quickly discovered that cable leakage was embarrassingly >>>> severe. So >>>> I shut down and began contemplating a fiber link. But then reality set in >>>> and I realized >>>> that running fiber across the house had its own big problems, so I set the >>>> project aside. >>>> >>>> Dana >>>> >>>> >>>> On Sat, Aug 28, 2021 at 3:32 PM Bob kb8tq <kb8tq@n1k.org> wrote: >>>> >>>>> Hi >>>>> >>>>> With a whole variety of pretty good OCXO’s going for cheap money >>>>> on eBay, it’s likely less expensive to do cleanup oscillators on the link >>>>> compared to going crazy with low noise optical this or that. Yes, you >>>>> will be getting something in the high 150’s for noise, but still pretty >>>>> good >>>>> for $10. >>>>> >>>>> If you need better, spend $50 or so on a 10811. Still less money than >>>>> some of the crazy fiber stuff. >>>>> >>>>> With either one, send over a high enough frequency that the loop isn’t >>>>> dealing with reference spurs in any significant way. Given the clock rates >>>>> Ethernet runs at these days, that part should be fairly straightforward. >>>>> >>>>> This *assumes* that there is a crossover somewhere practical between >>>>> the fiber noise and the noise on the optical gear. You should be able to >>>>> work out what it is with some fairly normal phase noise or ADEV testing. >>>>> >>>>> Bob >>>>> >>>>>> On Aug 28, 2021, at 3:03 PM, Dana Whitlow <k8yumdoober@gmail.com> wrote: >>>>>> >>>>>> I was looking for something similar about 18 months or so ago. Although >>>>> I >>>>>> haven't taken any >>>>>> action yet, I concluded that one could do a nice job for under $200 per >>>>>> segment, including the >>>>>> transmitter and receiver modules and lots of connectorized multimode >>>>>> fiber. What I *don't* know >>>>>> is what the phase noise performance would be, except that I do know that >>>>>> the fiber's VF *is* >>>>>> materially influenced by temperature. >>>>>> >>>>>> I was looking primarily at the HFBR-2416 for the fiber receiver, and the >>>>>> HFBR-1412 (standard >>>>>> power) or the HFBR-1414 (high power option) for the transmitter Unlike >>>>>> most of the available >>>>>> models, these are fundamentally analog devices, meaning that you can >>>>>> transmit sinewave >>>>>> 10 MHz through them. At the time I was looking, Mouser was selling these >>>>>> for about $20 each. >>>>>> >>>>>> See the datasheet at >>>>>> >>>>> https://www.mouser.com/datasheet/2/678/AV02-0176EN_2019-02-15-1827546.pdf >>>>>> with particular attention to page 21 regarding the HFBR-2416 receiver. >>>>>> >>>>>> I was also looking at Fiber Instrument Sales for patch cords. We bought >>>>> a >>>>>> lot of fiber stuff from >>>>>> them at Arecibo, and I was always happy with them. See: >>>>>> >>>>> https://www.fiberinstrumentsales.com/catalog-cable-assemblies?gclid=Cj0KCQjwvaeJBhCvARIsABgTDM7eNTkP2nQbyFzhcwDE38VnSEP879MBKV1ZyDq2YrnEtOn7_VfzjbkaAtpfEALw_wcB >>>>>> Somebody had pointed out yet another source of connectorized fibers >>>>> ("patch >>>>>> cords") to me, but I cannot find the name >>>>>> at the moment. >>>>>> >>>>>> Dana K8YUM >>>>>> >>>>>> >>>>>> On Sat, Aug 28, 2021 at 11:52 AM AC0XU (Jim) <James.Schatzman@ac0xu.com> >>>>>> wrote: >>>>>> >>>>>>> I am hoping that you can help me about a couple of things: >>>>>>> >>>>>>> 1) My time-nuts summaries sometimes appear unformatted and unreadable. >>>>> All >>>>>>> the text from all the postings is crammed together without spacing. How >>>>> can >>>>>>> I fix it? >>>>>>> >>>>>>> 2) I want to distribute 10 MHz references by fiber. There are >>>>>>> RF-over-Fiber products available, but too expensive for me (thousands of >>>>>>> $$$ per xmit/rcv set). I am thinking that it should be possible to use >>>>>>> fiber Ethernet components to do this. I don't mean IEEE 1588 but a much >>>>>>> simpler, no-computer-required, solution. Possibly just converting sine >>>>> wave >>>>>>> (coax) to square wave (fiber) to sine wave (coax). I am looking for a >>>>> low >>>>>>> cost solution. Any thoughts or recommendations?? >>>>>>> >>>>>>> Thanks! >>>>>>> >>>>>>> Jim >>>>>>> _______________________________________________ >>>>>>> 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. >>>>> _______________________________________________ >>>>> 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. >>> _______________________________________________ >>> 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. > _______________________________________________ > 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.

Hi With *any* cable setup, proper termination is vital. An improperly terminated balanced line can be just as bad as a poorly terminated coax. Things like common mode chokes are part of a *lot* of setups. What gets messy is that a lot of gear does not properly terminate the cable. It’s high-z so you can run a bunch of them with Tee connectors or some other strange approach. >20 db of return loss is *not* what most cables get terminated in. It doesn’t take a lot of coax to get a quarter wave at 10 MHz. Anything nearly that long is going to be a radiator if you let it. This all gets a bit insane if you have multiple 10 MHz sources (like devices you are testing). Close in phase noise and ADEV both can get really strange as a result. Lots of issues …. Bob > On Aug 29, 2021, at 10:44 AM, Dana Whitlow <k8yumdoober@gmail.com> wrote: > > Andy, > > Balanced twisted pair may be helpful, but only if adequate precautions are > taken to > avoid creation of common mode *currents *on the line*.* > > Dana > > > On Sun, Aug 29, 2021 at 9:34 AM Andy Talbot <andy.g4jnt@gmail.com> wrote: > >> Hence my observation that balanced twisted pair might be a better solution >> than coax for 10MHz distribution >> Removes all possibility of ground loops >> >> Andy >> www.g4jnt.com >> >> >> >> On Sun, 29 Aug 2021 at 15:22, Dana Whitlow <k8yumdoober@gmail.com> 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, >>> namely a cable that mostly went around the outside of the house for TV >>> distribution. >> _______________________________________________ >> 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.

This has been an interesting thread. I purchased some 1/4" FSJ with BNC connectors from the usual auction site years ago for time nuts use but never installed it. It does seem to be a bit of a hassle to use in my time lab (I do use some FSJ with N connectors in parts of my home amateur radio station.) I suspect I haven't looked hard enough for troubling leakage at 10 MHz from the RG400 I mostly use. I have the FSJ to fall back on if I take my time nuts hobby to the next level. Some of the fiber ideas seem promising as well. Mark Spencer mark@alignedsolutions.com 604 762 4099 > On Aug 29, 2021, at 10:29 AM, Robert DiRosario <ka3zyx@comcast.net> wrote: > > Andrew Sureflex (FSJ) is a lot more flexible then the LDF4 Healix, which is what you find a > lot of on ebay and at hamfests. > > Here is some 1/4" Sureflex, new: > > Andrew Type N Male to Type N Male Sureflex Cable 30 feet F1RNA-PNMNM-30-L1 NEW! > https://www.ebay.com/itm/173863049072 > US $30.00 + $13.02 Shipping. For two pieces shipping goes to $16.33, for three $22.90 > > You can cut it with a hacksaw, do NOT use wire cutters. Connectors can be > installed with just hand tools. > > If you move the test equipment around it's not very practical, but if it's setup on > a bench or in a rack it will work. > > Robert > > > >> On 08/29/2021 09:51 AM, Bob kb8tq wrote: >> Hi >> >> Skin depth is what gets you with most coax at 10 MHz, even with the “double >> shield” stuff. Hardline with a nice heavy outer would do better. It’s not terribly >> practical around the typical lab. Might not be a bad choice for a “burry in the yard” >> setup though. With normal cable, the losses from the soil at normal burial >> depths make a good shield, that makes dealing with it questionable even there …. >> >> Bob >> >>> On Aug 29, 2021, at 9:36 AM, Robert DiRosario <ka3zyx@comcast.net> wrote: >>> >>> What about double shielded RG-223, or Thinnet ethernet cable? >>> Most Thinnet has both a braided shield and a foil wrap. >>> >>> Robert >>> >>>> On 08/28/2021 08:26 PM, Bob kb8tq wrote: >>>> Hi >>>> >>>> Anything you do that has a bunch of 10 MHz cables running out from here or there >>>> will impact your ability to listen to WWV at 10 MHz :) Other than killing all the sources, >>>> there is no silver bullet. >>>> >>>> Bob >>>> >>>>> On Aug 28, 2021, at 7:57 PM, Dana Whitlow <k8yumdoober@gmail.com> wrote: >>>>> >>>>> Bob, my own motivation for going to fiber was entirely different. I >>>>> simply wanted to >>>>> run 10 MHz all over the place from reference sources in disparate >>>>> locations in the >>>>> house, and I quickly discovered that cable leakage was embarrassingly >>>>> severe. So >>>>> I shut down and began contemplating a fiber link. But then reality set in >>>>> and I realized >>>>> that running fiber across the house had its own big problems, so I set the >>>>> project aside. >>>>> >>>>> Dana >>>>> >>>>> >>>>> On Sat, Aug 28, 2021 at 3:3

On 8/29/21 10:29 AM, Robert DiRosario wrote: > Andrew Sureflex (FSJ) is a lot more flexible then the LDF4 Healix, > which is what you find a > lot of on ebay and at hamfests. > > Here is some 1/4"  Sureflex, new: > > Andrew Type N Male to Type N Male Sureflex Cable 30 feet > F1RNA-PNMNM-30-L1 NEW! > https://www.ebay.com/itm/173863049072 > US $30.00 + $13.02 Shipping.  For two pieces shipping goes to $16.33, > for three $22.90 > > You can cut it with a hacksaw, do NOT use wire cutters. Connectors can be > installed with just hand tools. > > If you move the test equipment around it's not very practical, but if > it's setup on > a bench or in a rack it will work. > > Robert ya know.. system cost for optical fiber is probably cheaper than hardline - the cable certainly is (about $15 for a 100 ft duplex single mode). And the analog/optical converters at either end are probably cheaper than hardline coax connectors. And *way* easier to install. We just need to figure out which COTS media converter is right for "time-nuts" usage.

While they may not have ideal behavior with temperature (and

I do certainly beleive that optical transmission is the 

On Sun, Aug 29, 2021 at 10:43:51AM -0400, paul swed wrote: > Wellll my only issue is every time we had a lightning storm it seemed to > fry the ICs. While they may not have ideal behavior with temperature (and related phase/group delay changes) the old antique 10Mbs era balanced twisted pair ethernet transformer/filter modules did eliminate common mode energy getting into the receivers (and transmitter) which it sounds like was the cause of your lightning EMP problem. For 10 MHz these ought to work pretty well with twisted pairs as they provide galvanic isolation breaking ground loops. Not completely clear what the common mode Z of the things is at 10 MHz... but unless there is a deliberate cap from a center tap to local ground I'd guess it would be significantly high given just winding to winding capacitance. I do certainly beleive that optical transmission is the better solution... however. -- Dave Emery N1PRE/AE, die@dieconsulting.com DIE Consulting, Weston, Mass 02493 "An empty zombie mind with a forlorn barely readable weatherbeaten 'For Rent' sign still vainly flapping outside on the weed encrusted pole - in celebration of what could have been, but wasn't and is not to be now either."

-------- David I. Emery writes: > On Sun, Aug 29, 2021 at 10:43:51AM -0400, paul swed wrote: > Not completely clear what the common > mode Z of the things is at 10 MHz... Twisted pair is 135 Ohm. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk@FreeBSD.ORG | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence.

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

FWIW we've played with various SMA-to-SFP converter boards in the lab for 10MHz or 100MHz distribution. A bare-bones SFP board is e.g. https://github.com/aewallin/SFP-Breakout-Board That interfaces directly to the differential AC-coupled TX and RX pins of an SFP. If you want some buffering (and limited bandwidth at the same time) you can put an op-amp as a buffer and a transformer to convert to/from the differential TX/RX. Here's a design I've used https://github.com/aewallin/SFP2SMA_2018.03 We also made a box around that board: http://www.anderswallin.net/2020/12/sfp-board-in-a-box/ If your requirements are somewhere in 1e-14 or worse then this type of passive frequency distribution should work fine for maybe a few km fiber runs. Anders On Mon, Aug 30, 2021 at 8:13 AM Poul-Henning Kamp <phk@phk.freebsd.dk> wrote: > -------- > David I. Emery writes: > > On Sun, Aug 29, 2021 at 10:43:51AM -0400, paul swed wrote: > > > Not completely clear what the common > > mode Z of the things is at 10 MHz... > > Twisted pair is 135 Ohm. > > -- > Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 > phk@FreeBSD.ORG | TCP/IP since RFC 956 > FreeBSD committer | BSD since 4.3-tahoe > Never attribute to malice what can adequately be explained by incompetence. > _______________________________________________ > 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. >

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.

On 8/29/21 11:07 PM, Anders Wallin wrote: > FWIW we've played with various SMA-to-SFP converter boards in the lab for > 10MHz or 100MHz distribution. > > A bare-bones SFP board is e.g. > https://github.com/aewallin/SFP-Breakout-Board > That interfaces directly to the differential AC-coupled TX and RX pins of > an SFP. > > If you want some buffering (and limited bandwidth at the same time) you can > put an op-amp as a buffer and a transformer to convert to/from the > differential TX/RX. > Here's a design I've used https://github.com/aewallin/SFP2SMA_2018.03 > We also made a box around that board: > http://www.anderswallin.net/2020/12/sfp-board-in-a-box/ > > If your requirements are somewhere in 1e-14 or worse then this type of > passive frequency distribution should work fine for maybe a few km fiber > runs. > > Anders > This is really cool..