Re: [time-nuts] Installing GPS Antenna

2017-02-18 Thread Bob Camp 
Hi

Let’s back off a bit here. 

If the chimney is above the rest of the house, simply putting the antenna a 
foot or
two above the chimney will get you past the immediate issues of the house 
blocking
or reflecting stuff. 

If the top of the chimney has a view to the south down to about 10 degrees off 
the 
horizon *and* it maintains that for most of a +/- 100 degree arc, that is doing 
fine.

If the application is just timing, having a mount that does not move around a 
lot 
is a really good idea. 

With any antenna, putting it up higher than needed simply makes it a better 
lightning 
target (you *will* have proper grounding and suppression on this antenna, it 
still 
is not perfect).

On a GPSDO with a good sky view, you may well set the elevation mask to 
something 
like 20 or even 30 degrees to improve the timing performance. When you do, all 
the effort to get a sky view down to 10 degrees becomes a bit less worthwhile. 

=

So: what is the reason for getting the antenna 15 feet above the chimney?

Bob

> On Feb 18, 2017, at 12:57 AM, time...@metachaos.net wrote:
> 
> I have finally ordered a GPSDO (probably get here in April). In the meantime,
> I have the GPS antenna (Luctel, 26Db). I picked up a 20' solid section of 1 
> 1/4"
> copper pipe at the plumbing store with the intention of mounting it to my
> chimney.
> 
> My question is about the stability of that mounting. I expect that 16 or 17
> feet of the pipe will be above the chimney. The weight of the GPS antenna is
> trivial. The effective cross section area of the pipe is very small as well,
> so I would think that wind effects would be pretty small even for a good
> breeze.
> 
> Will that be sufficiently stable, or will I need to include guy wires? If so,
> are there any recommendations in that area. I don't really have any experience
> putting up antennas. I know that TV antennas are much heavier and, even though
> not mounted as high, still 10' or so is common without guy wires.
> 
> Thanks.
> 
> Michael
> 
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Re: [time-nuts] Installing GPS Antenna

2017-02-18 Thread Pete Lancashire 
I pretty much agree on the fittings, only ones designed for outdoor
and contact with copper. Stainless steel, bronze etc.

I disagree about guy wires, Are you in a area that gets winds and
gusts > 30 mph  ? Then I would guy it no matter what, it may even be
code.

Ever get below freezing where you are, that pipe could end up easily
having 10 lbs of ice per foot, thats 200 lbs and then a 5x increase in
wind resistance.

=pete

On Fri, Feb 17, 2017 at 11:41 PM, Chris Albertson
 wrote:
> Copper?  What an expensive material to use.   Galvanized iron pipe is
> cheaper and very strong.   But even the thinner "type M" copper pipe
> is strong enough if it is 1 1/4" diameter.
>
> You should not need guy wires on such a short mast.   You will need
> likely the proper threaded adaptor to fit the antenna mount.   Run the
> coax antenna lead down the center of the pipe.  Also be sure and
> ground the pipe to a ground rod.   The ground wire needs to be (from
> memory) #8 or larger.   You don't want a 20 foot tall ungrounded
> lightening rod up on the roof.  Electric code requires the ground.
>
> One thing, because you used copper pipe use either copper wire for the
> ground or if using aluminum wire use the special fittings/clamps
> designed for connecting aluminum to copper.
>
> I assume this is an unused chimney?
>
> On Fri, Feb 17, 2017 at 9:57 PM,   wrote:
>> I have finally ordered a GPSDO (probably get here in April). In the meantime,
>> I have the GPS antenna (Luctel, 26Db). I picked up a 20' solid section of 1 
>> 1/4"
>> copper pipe at the plumbing store with the intention of mounting it to my
>> chimney.
>>
>> My question is about the stability of that mounting. I expect that 16 or 17
>> feet of the pipe will be above the chimney. The weight of the GPS antenna is
>> trivial. The effective cross section area of the pipe is very small as well,
>> so I would think that wind effects would be pretty small even for a good
>> breeze.
>>
>> Will that be sufficiently stable, or will I need to include guy wires? If so,
>> are there any recommendations in that area. I don't really have any 
>> experience
>> putting up antennas. I know that TV antennas are much heavier and, even 
>> though
>> not mounted as high, still 10' or so is common without guy wires.
>>
>> Thanks.
>>
>> Michael
>>
>> ___
>> time-nuts mailing list -- time-nuts@febo.com
>> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
>
>
>
> --
>
> Chris Albertson
> Redondo Beach, California
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Re: [time-nuts] Installing GPS Antenna

2017-02-18 Thread Chris Albertson 
Copper?  What an expensive material to use.   Galvanized iron pipe is
cheaper and very strong.   But even the thinner "type M" copper pipe
is strong enough if it is 1 1/4" diameter.

You should not need guy wires on such a short mast.   You will need
likely the proper threaded adaptor to fit the antenna mount.   Run the
coax antenna lead down the center of the pipe.  Also be sure and
ground the pipe to a ground rod.   The ground wire needs to be (from
memory) #8 or larger.   You don't want a 20 foot tall ungrounded
lightening rod up on the roof.  Electric code requires the ground.

One thing, because you used copper pipe use either copper wire for the
ground or if using aluminum wire use the special fittings/clamps
designed for connecting aluminum to copper.

I assume this is an unused chimney?

On Fri, Feb 17, 2017 at 9:57 PM,   wrote:
> I have finally ordered a GPSDO (probably get here in April). In the meantime,
> I have the GPS antenna (Luctel, 26Db). I picked up a 20' solid section of 1 
> 1/4"
> copper pipe at the plumbing store with the intention of mounting it to my
> chimney.
>
> My question is about the stability of that mounting. I expect that 16 or 17
> feet of the pipe will be above the chimney. The weight of the GPS antenna is
> trivial. The effective cross section area of the pipe is very small as well,
> so I would think that wind effects would be pretty small even for a good
> breeze.
>
> Will that be sufficiently stable, or will I need to include guy wires? If so,
> are there any recommendations in that area. I don't really have any experience
> putting up antennas. I know that TV antennas are much heavier and, even though
> not mounted as high, still 10' or so is common without guy wires.
>
> Thanks.
>
> Michael
>
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.



-- 

Chris Albertson
Redondo Beach, California
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