[time-nuts] RG6 or LMR400 for GPS Antenna (Symmetricom 58532A and T-bolt)
Graham
planophore at aei.ca
Fri Apr 22 23:18:56 UTC 2016
I think all RG6 cable has a solid core otherwise the F type connector
wouldn't work.
I almost universally use an RG6 type cable for all my receive only systems.
In fact, I came across several hundred feet of a Belden product labled
1694A HD-SDI Precision Video Cable 4.5GHz. This has a solid copper
center, foil shield and on top of that a copper braid shield. This
Belden cable has, at least in the comparison of Belden vs other's data
sheets, a wee bit better performance.
So far has been working very for me whenever I use it. I have one
symetricom "puck" antenna mounted just outside on the deck I use for
testing using about 50 feet of this cable and works well.
And just to show how not overly critical cable is, my main GPS antenna
mounted up on the roof just above the peak is a "bullet" type (MaxRad
TMG-26N - 26db gain) which feeds my lab through 65 feet of RG-8X cable
which what I had lying around at the time with the good intention of
replacing with "better" cable later in the summer. I have since moved my
lab around and have extended that 65 feet of RG-8X with an additional 25
feet of RG-58 to a Symetricom 58535A one to two splitter (which has some
gain as well). The connection between the connection between the RG-8X
and RG-58 is made with a crimp on male BNC on one side and a crimp on
female on the other to eliminate using two male and one barrel connector.
Good intentions being as they may, the RG-8X and RG-58 extension has
worked so well that I have never bothered changing it out and that is
now going on six years. When it needs changing out I will replace with
quality RG6.
Like many things in life there is a sense of accomplishment and pleasure
in tweaking something out to it's utmost; likewise there is also a sense
of accomplishment and pleasure is making do with whats available and
still getting to where you want to get. It all depends on which cup you
wish to drink from.
cheers, Graham ve3gtc
On 2016-04-22 21:38, Bob Stewart 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 <rstasel at uoregon.edu> wrote:
>
> Subject: Re: [time-nuts] RG6 or LMR400 for GPS Antenna (Symmetricom 58532A and T-bolt)
> To: "Discussion of precise time and frequency measurement" <time-nuts at febo.com>
> 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 <paulswedb at gmail.com>
> 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 <rstasel at uoregon.edu>
> 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 <paulswedb at gmail.com>
> 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 <rstasel at uoregon.edu>
> >> 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 <kb8tq at n1k.org>
> 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 <rstasel at uoregon.edu>
> 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
> >>>>>>
> >>>>>>
> >>>>>>
> _______________________________________________
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> >>>>>
> >>>>>
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