[time-nuts] RG6 or LMR400 for GPS Antenna (Symmetricom 58532A and T-bolt)

Fri Apr 22 00:54:35 UTC 2016

All accurate accept the aging rate of any coax/heliax. Useful life =Years
of expected life/woodpecker attacks. I would never have believed it but I
am actually having trouble with those birds. :-) Just never know.
Regards
Paul
WB8TSL

On Thu, Apr 21, 2016 at 5:33 PM, Tom Holmes <tholmes at woh.rr.com> wrote:

> Ryan...
>
> I've done a lot of tower work over the years, and have taken down quite a
> few antennas, which of course meant removing whatever seal was used and
> separating the connector halves. I have never found an N connector seized.
> Usually a gentle twist using a pair of pliers will break the sleeve loose.
> And I should point out that you don’t need to torque the sleeve any more
> than gently when you mate the halves. Too much torque will distort the
> internals and possibly damage things, or at least make the inherent SWR
> bump a bit worse.
>
> Frankly, I would be concerned about the anti-seize compound migrating into
> the inner workings of the connector and adding a bit of loss, which is
> another reason not to use it. I'm not a big fan of the greases that are
> suggested for use inside of connectors as a way to keep moisture out, again
> because of their affect on the losses at 1575 MHz.
>
> My observations with various types of coax, such as Belden brand RG-8 and
> RG-213, as well as Andrew Heliax is that even after 30 years outside in
> Ohio weather, the outer jacket holds up quite well. Unsupported sections of
> the RG types of coax that can flop around in the wind sometimes show cracks
> and splits from years of flexing, however. The occasional punch through
> from lightning has been found as well near the tops of 100' towers.
>
> Don’t get too uptight about the cabling; just do your best to make it
> neat, reasonably well sealed (you are putting it in a pipe outside, that's
> very good), and keep the bend radii gentle and you'll be fine.
>
> Have fun!
>
> Tom Holmes, N8ZM
>
>
> -----Original Message-----
> From: time-nuts [mailto:time-nuts-bounces at febo.com] On Behalf Of Ryan
> Stasel
> Sent: Thursday, April 21, 2016 1:08 PM
> To: Discussion of precise time and frequency measurement <
> time-nuts at febo.com>
> Subject: Re: [time-nuts] RG6 or LMR400 for GPS Antenna (Symmetricom 58532A
> and T-bolt)
>
> 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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