[time-nuts] First Post from Max NG7M

Chris Albertson albertson.chris at gmail.com
Sat Apr 25 02:11:03 EDT 2015


The GPS satellites are located to the south all the way down to the
horizon but to the north they do not extend all the way to the horizon
unless you live very far south, like in Mexico.    So you may not need
to see all the way to the northern horizon.  You do want to see the
horizon to the south.

But more important is that the antenna is away from reflective
surfaces like metal roof vents and flashings.  The short mast does
this.

Do you need this?  If you are just trying to keep an HF transmitter
on-frequency then no.

On Fri, Apr 24, 2015 at 9:17 PM, M. George <m.matthew.george at gmail.com> wrote:
> Hi Chris, thanks for the feedback... the cost is not a concern, is making
> the run to the peak of the roof worth it as far as the GPS reception /
> signal is concerned?  Where I have a clean view south, is it worth it to
> run the coax up through the attic and to the peak of the roof so I get a
> totally clear 360 view to the north?  If not, it's much easier to put my
> mast mount a few feet back on the eve of the roof.
>
> I have the LMR-400 collecting dust and the RG-213 sized N connectors... so
> I'll just use what I have handy.
>
> Max
>
>
>
> On Fri, Apr 24, 2015 at 8:39 PM, Chris Albertson <albertson.chris at gmail.com>
> wrote:
>
>> What is the problem withplaccing the GPS antenna all the way up on the
>> roof ridge?  If you can get an iron pipe and make short mast and place
>> the GPS Antenna a few feet above the top of the roof.  Run the pipe
>> through the roof into the attic and run the coax cable inside the
>> pipe.  This way the coax is shielded from the weather and sun and you
>> have a lifetime installation.
>>
>> Was the problem the cost of the cable or the loss in that cable?
>> Don't worry about it.  If cost is the problem then use the double
>> shield Cable TV cable with the swagger-on F connectors.  Yes it is 75
>> ohm but this is the cable Trimble recommends.   If the run is very
>> long and there is loss, get either a higher gain antenna or an in-line
>> amplifier.
>>
>> You can work around cost and loss in that cable but you can't work
>> around antenna location.  You do NOT need low-loss LMR cable.  RG59
>> works.
>>
>>
>>
>> On Fri, Apr 24, 2015 at 5:59 PM, M. George <m.matthew.george at gmail.com>
>> wrote:
>> > Hello Time Nuts!  This is my first post, but I have been lurking about
>> for
>> > several weeks now... what started out as a project to find a stable time
>> > reference for a QS1R I have been running 24x7 for years on the NC7J CW
>> > Skimmer server has taking me down a whole to obsession after finding time
>> > nuts and GPSDO information.  I now have a clean Trimble TBolt and the
>> > Lucent RFTG-u REF0/1 ready to roll... not to mention a couple of
>> Raspberry
>> > Pi 2's with NTP servers on them setup and ready to accept a PPS signal
>> from
>> > my new gizmos!  I'm following the path that has been traversed many times
>> > before and I appreciate all the info that I have already gleaned from the
>> > time nuts list.
>> >
>> > Anyway, I didn't get the TBolt for free form China, but it' s a clean
>> > machine and seems to be settling down nice after running for a few
>> days...
>> >
>> > Another reason for the post here is related to an installation of a GPS
>> > antenna on my roof.  I have a $38 ePay bullet that I'm going to put up
>> > tomorrow and make a run of solid conductor LMR-400 to the antenna with a
>> > nice little J-Pole mount.  Or potentially 2 runs for 2 GPS antennas.
>> >
>> > I'm lucky to have a southern exposure off the back of house with my ham
>> > shack in the raised basement right in the south west corner of the house
>> so
>> > the new GPS antenna project works out well to keep the coax run short as
>> > possible to the GPS antenna. (see the pics attached or link at the bottom
>> > of my verbose post here)
>> >
>> > I'm shocked at how well a cheapie mushroom GPS antenna is doing close to
>> > the back of the house on a broom stick at the moment.  Anyway, I know
>> that
>> > to even think about being a time nut, I need to get a better location for
>> > the GPS antenna (two really eventually or a splitter).
>> >
>> > I have attached a picture of my house and you can pretty much see my
>> > options.  Do I go up and simply put the antenna on the roof close to the
>> > edge above the rain gutter or do I take it all the way to the peak of the
>> > roof where you can see a WX station and dual band antenna?
>> >
>> > I realize I can calculate the loss in the extra coax, but I'm more
>> > concerned about the fact that I have a SteppIR BigIR vertical HF antenna
>> in
>> > my back yard and I run power / 1KW+ at times on HF (I'm a CW nut!).  The
>> > coax run to the top of the eve is going to be about 30-40 feet of coax
>> > roughly, if I take it all the way to the peak that's probably another 30
>> > feet or so.  70-80 feet max if I go to the roof.
>> >
>> > Would a true time-nut need to have the bullet antenna at the peak of the
>> > root for a true clear view of the horizon even to the north 360 degrees?
>> > Will it bug me down the road that I didn't just run the bullet / coax up
>> to
>> > the peak of the roof down the road, regardless of my concerns about RF
>> from
>> > my HF operating potentially getting into the GPS antenna? (I'll probably
>> > put a voltage limiter on the GPS feed line).  The antenna has a nice
>> direct
>> > southern view off the eve.
>> >
>> > Thoughts for a first time poster and time-nut wanna be?  The eve or the
>> > peak?
>> >
>> > Here is a link to the house pic and a few pictures of the TBolt gizmo
>> that
>> > arrived from China this week:
>> http://www.nc7j.com/downloads/NG7M/Time-Nuts/
>> >
>> > I attached the pics too... is that okay on the time nut list?  Picture
>> > attachments?
>> >
>> > Max NG7M
>> >
>> >
>> >
>> > --
>> > M. George
>> >
>> > _______________________________________________
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>> > and follow the instructions there.
>>
>>
>>
>> --
>>
>> Chris Albertson
>> Redondo Beach, California
>> _______________________________________________
>> time-nuts mailing list -- time-nuts at febo.com
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>>
>
>
>
> --
> M. George
> _______________________________________________
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> and follow the instructions there.



-- 

Chris Albertson
Redondo Beach, California



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