Hi There are a significant number of antennas out there (marine and survey) that run 50 db amplifiers in them. That’s *way* more than a TBolt was designed for. Some of the early GPS gear needed a *lot* of gain in front of it. To maintain compatibility with old setups, some manufacturers have continued to do high gain antennas.
I happen to have a fleet of high gain antennas mounted out on the deck. They run their intended gear just fine through a 3 or 6 db splitter. The (an) other port of the splitter goes to a DC block and to an attenuator. That feeds an 8 or 16 way passive splitter for “other gear”. The setup works fine, I just have to keep track of what goes to which sort of gear. Bob > On Apr 22, 2016, at 7:53 PM, Nick Sayer via time-nuts <[email protected]> > wrote: > > Lady Heather does say what the S/N for each satellite is. I use a lot of PA6H > modules (the AdaFruit ones) and GPSMon also conveniently gives the S/N too. > It’s in the GPGSV sentences. > > I’m kinda blessed in that my antenna location is just outside the wall from > my workbench, and that position sees the whole sky down to easily 20 degrees > azimuth. I just swapped out a 4 port amplified splitter for an 8 port one. I > get an S/N of >50 for 5 satellites and >40 for another 5 much of the time and > quite frequently have 10 satellites being used and 11 in the list with > non-zero S/N. > > It’s a Gilsson marine antenna, and the coax is 30 feet of whatever it came > with. I took a look just now and it’s not labeled. It’s thinner than a pencil > and relatively inflexible. Their website says it’s RG58A/U, which seems like > an odd choice to me, but they claim 30 dB of gain in the antenna, so if it > has 10 dB of loss, there’s still 20 dB of gain before the splitter. > > The only oddity of my antenna system is that the Thunderbolt absolutely > *insists* on being on the power-pass port. If it’s on one of the DC-blocking > ports it gets no reception at all, despite the fact that all of the rest of > the systems are all perfectly happy. I kinda wanted to have my NTP server’s > module power it all because it’s the most permanent gizmo in the whole lab, > but the tBolt won’t have that. It was the same with my previous 4 port > amplified splitter too. I don’t quite know what to make of it, but the > solution is simple so long as I never get a second receiver/module that also > hates the DC-block ports. > > > >> On Apr 22, 2016, at 3:45 PM, Ryan Stasel <[email protected]> wrote: >> >> Bob, >> >> Fair enough. I’ll just stop worrying about it. =) >> >> I believe that number sounds like per 100 meter, not per 100 foot. Once I >> have the actual coax, as someone suggested, I’ll just hook some ends up, and >> check it. =) >> >> Sadly, I don’t have an SA, so checking the attenuation might be problematic. >> Though, could I not just use a function gen (signal gen), and a scope? >> Trying to think… I don’t have anything that’ll do 1.5Ghz though (or even >> close). >> >> Meh, overthinking… what Paul said. =) I’m sure it’ll be fine. Will the >> T-bolt actually complain about poor signal, or just not work reliably? And >> lastly, I guess, there’s a setting on the T-bolt to compensate for cable >> length. I assume that’s compensation for antenna cable length? I know I can >> figure that out with an SG and Scope, assuming the propagation delay is what >> the spec sheet claims to be (most RG6 seems to be right around 80%) (the >> home depot stuff seems to be 79%). >> >> -Ryan Stasel >> >>> On Apr 22, 2016, at 14:38 , Bob Stewart <[email protected]> wrote: >>> >>> Hi Ryan, >>> >>> For the few years I've been on time-nuts, I understood the consensus view >>> to be to get a good quality RG-6QS satellite cable. A few of the posts in >>> this thread have made me wonder if the consensus is changing, or if it's >>> just too much trouble to stand up to the crowd. I've got about 300 ft of >>> CerroWire RG-6QS leftover from Home Depot in the garage. I looked at the >>> datasheet, and it's confusing. For the attenuation at 1000MHz, they list >>> 21.45DB per hundred with the superscript "1". However there is nothing on >>> the page noting whether that "1" means per 100 feet or per 100 meters. >>> Looking at the competition it would appear that that's per meter. >>> Unfortunately, I don't have the right connectors to hook it up to my SA to >>> see. OTOH, 100 ft runs from this spool don't show any noticeable (i.e. >>> problematic) attenuation of the signal. Maybe someone else with a spool of >>> RG-6 in the garage could give use some real world attenuation figures at L1? >>> >>> But, rather than over-engineering or over-angsting this issue, it's >>> probably OK to just pick one and use it. It's not likely to make any real >>> difference unless you have a run in the many hundreds of feet. >>> >>> Bob - AE6RV >>> >>> -------------------------------------------- >>> On Fri, 4/22/16, Ryan Stasel <[email protected]> wrote: >>> >>> Subject: Re: [time-nuts] RG6 or LMR400 for GPS Antenna (Symmetricom 58532A >>> and T-bolt) >>> To: "Discussion of precise time and frequency measurement" >>> <[email protected]> >>> Date: Friday, April 22, 2016, 4:09 PM >>> >>> Paul, >>> >>> LOL! So, along those lines… >>> one other question, since I can’t find my belden, I’ll >>> be buying some coax. Anyone have any opinions about RG6 for >>> CCTV vs CATV? My understanding is the CCTV version always >>> has a solid copper center conductor (which in my mind would >>> mean less voltage loss for the DC power going to the >>> antenna), or I’m still overthinking it and should just go >>> with standard RG6? >>> >>> Thanks! >>> >>> >>> -Ryan Stasel >>> >>>> On Apr 21, 2016, at 13:04 >>> , paul swed <[email protected]> >>> wrote: >>>> >>>> Ryan a >>> slight heads up. >>>> Time Nuts is not about >>> time accuracy as many people assume. >>>> >>> Its actually about the time we all waste looking for what we >>> know we have. >>>> We just measure that time >>> accurately. >>>> I do not use anti seize. >>> Nothing against it just one more glob of stuff to >>>> deal with. >>>> If you use >>> the heat shrink and it seals your done for my 2 cents. >>>> Paul >>>> WB8TSL >>>> >>>> On Thu, Apr 21, 2016 >>> at 1:07 PM, Ryan Stasel <[email protected]> >>> wrote: >>>> >>>>> >>> All, >>>>> >>>>> >>> Really awesome answers, thanks! >>>>> >>>>> For the sealing question, it was more >>> of a “should I bother with something >>>>> like anti-seize” or the like on the >>> actual thread-thread N interface. The >>>>> actual connector crimp, was planning >>> on just using a couple layers of the >>>>> heat-shrink with adhesive. That is all >>> going to be internal to the mast >>>>> >>> anyway, so direct weather contact should be minimal. It’s >>> also on the side >>>>> of my chimney, >>> that gets very little to no direct sun, so UV exposure >>>>> should be minimal. But good note on >>> that regard. >>>>> >>>>> Pete, thank you very much for the info >>> wrt the antenna and amp, and also >>>>> >>> the fact the Trimble starter kit came with RG6. I’m going >>> to see what my >>>>> seller wants for >>> LMR400, but otherwise, I’ll just use RG6. It’s >>> certainly >>>>> easier to handle. I did >>> find some datasheets on the stuff that Home despot >>>>> (har har) sells (Southwire ( >>>>> http://www.southwire.com/ProductCatalog/XTEInterfaceServlet?contentKey=prodcatsheetOEM80)). >>>>> I swear I have a box of Belden >>> somewhere, but I can’t seem to find it. >>>>> >>>>> Thanks >>> again! >>>>> >>>>> >>> -Ryan Stasel >>>>> >>>>>> On Apr 21, 2016, at 06:02 , paul >>> swed <[email protected]> >>> wrote: >>>>>> >>>>>> With respect to sealing. Everyone >>> has a method. >>>>>> I use what I >>> learned in the Navy. I could see how well the connections >>>>> held >>>>>> up >>> in the worst conditions sun cold heat wet humidity... >>>>>> Layer of rubber tape >>>>>> scotch kote >>>>>> Layer of plastic tape >>>>>> scotch kote >>>>>> If done well the connector >>> releases just fine even after 5 or more >>>>> years. I >>>>>> >>> want to say 10. But then woodpeckers have a way of >>> shortening the life of >>>>>> >>> connectors and coax. >>>>>> The >>> approach is really layers and the top to deteriorate over >>> time... >>>>>> But as I say everyone >>> has their own approach. >>>>>> >>> Regards >>>>>> Paul >>>>>> WB8TSL >>>>>> >>>>>> On >>> Wed, Apr 20, 2016 at 9:03 PM, Ryan Stasel <[email protected]> >>>>> wrote: >>>>>> >>> >>>>>>> Bob/Paul, >>>>>>> >>>>>>> Thanks. And there's the >>> rub... Who knows what the specs are on >>> "generic" >>>>>>> RG6 QS. >>> I'll see what my seller wants for their LMR400, but >>> otherwise >>>>> yeah, >>>>>>> RG6 is just easier. I have >>> both compression and crimp connectors for it, >>>>>>> including some RG6 >>> N-connectors (yeah, they're probably for LMR300, but >>>>>>> they work). >>>>>>> >>>>>>> Other question: any tips for >>> the exterior N connection? I can >>>>>>> "weatherproof" the >>> actual cable-connector crimp, but I'm curious if >>>>> anyone >>>>>>> bothers to "lube" >>> the N connector to keep moisture from otherwise >>>>> seizing >>>>>>> it up. >>>>>>> >>>>>>> Thanks! >>>>>>> >>>>>>> Ryan Stasel >>>>>>> IT Operations Manager, SOJC >>>>>>> University of Oregon >>>>>>> >>>>>>> Sent from my iPhone >>>>>>> >>>>>>>> On Apr 20, 2016, at 17:00, >>> Bob Camp <[email protected]> >>> wrote: >>>>>>>> >>>>>>>> Hi >>>>>>>> >>>>>>>> RG-6 Quad Shield should be >>> fine as long as it’s meeting the published >>>>>>> specs. The advantage of >>> LRM-400 is that you likely *know* where it came >>>>>>> from and what the specs >>> are. >>>>>>>> >>>>>>>> If you decide to split the >>> antenna between GPSDO’s, a powered splitter >>>>>>> is a really good idea. Each >>> time you split another 2 ways, you loose 3 >>>>> db. >>>>>>> >>> Get at least a 4 way splitter …. >>>>>>>> >>>>>>>> Bob >>>>>>>> >>>>>>>>> On Apr 20, 2016, at >>> 4:41 PM, Ryan Stasel <[email protected]> >>> wrote: >>>>>>>>> >>>>>>>>> All, >>>>>>>>> >>>>>>>>> I’m going to be >>> installing a “permanent” antenna at home, and will >>>>> need >>>>>>> >>> a run of about 100ft to get from my workstation, to the mast >>> I’ll be >>>>>>> mounting the >>> antenna on (Symmetricom 58532A). I’ve seen some >>> indication >>>>>>> that both the >>> antenna and the Trimble Thunderbolt won’t have any >>> issues >>>>>>> with running over >>> 75ohm cable, but thought I’d ask the “experts” >>> whether >>>>>>> I’d be better off >>> with some RG6 Quad-shield, or LMR400 (I’ve got a local >>>>>>> source that doesn’t know >>> what LMR400 is, or what it’s worth)? >>>>>>>>> >>>>>>>>> Obviously I’d prefer >>> to run and crimp RG6, but if I’d be better off >>>>>>> with LMR400, I’d rather run >>> that now than go back into the crawlspace >>>>>>> again. =) >>>>>>>>> >>>>>>>>> Also, if it helps, >>> I’ll probably have a Symmetricom/HP 58516A at/near >>>>>>> the T-bolt so I can experiment >>> with other GPS(DO)s as well (especially >>>>> one >>>>>>> >>> of the JRMiller boards I bought and built (but never >>> finished) ages >>>>> ago). >>>>>>> Which brings the question, >>> will the T-bolt provide the oomph needed to >>>>>>> power that splitter and the >>> antenna over that length of cable? >>>>>>>>> >>>>>>>>> Thanks! >>>>>>>>> >>>>>>>>> -Ryan Stasel >>>>>>>>> >>>>>>>>> >>>>>>>>> >>> _______________________________________________ >>>>>>>>> time-nuts mailing list >>> -- [email protected] >>>>>>>>> To unsubscribe, go >>> to >>>>>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>>>>>>>> and follow the >>> instructions there. >>>>>>>> >>>>>>>> >>> _______________________________________________ >>>>>>>> time-nuts mailing list -- >>> [email protected] >>>>>>>> To unsubscribe, go to >>>>>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>>>>>>> and follow the >>> instructions there. >>>>>>> >>> _______________________________________________ >>>>>>> time-nuts mailing list -- [email protected] >>>>>>> To unsubscribe, go to >>>>>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>>>>>> and follow the instructions >>> there. >>>>>>> >>>>>> >>> _______________________________________________ >>>>>> time-nuts mailing list -- [email protected] >>>>>> To unsubscribe, go to >>>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>>>>> and follow the instructions >>> there. >>>>> >>>>> >>> _______________________________________________ >>>>> time-nuts mailing list -- [email protected] >>>>> To unsubscribe, go to >>>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>>>> and follow the instructions there. >>>>> >>>> >>> _______________________________________________ >>>> time-nuts mailing list -- [email protected] >>>> To unsubscribe, go to >>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>>> and follow the instructions there. >>> >>> _______________________________________________ >>> time-nuts mailing list -- [email protected] >>> To unsubscribe, go to >>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>> and follow the instructions there. >>> _______________________________________________ >>> time-nuts mailing list -- [email protected] >>> To unsubscribe, go to >>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>> and follow the instructions there. >> >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
