[time-nuts] WTB: GPS Antenna Splitter

Magnus Danielson magnus at rubidium.dyndns.org
Tue Oct 7 08:25:31 EDT 2014


Hi,

Regarding DC load, a friend had problems, so my quick fix was a BNC tee with a SMD inductor in series with a load resistor between tip and shell on one of the BNC branches. Fixed the problem so that when the receiver saw the load it also accepted the GPS signal it was already seeing but disqualifying.

Cheers, 
Magnus

<div>-------- Originalmeddelande --------</div><div>Från: Björn Gabrielsson <bg at lysator.liu.se> </div><div>Datum:07-10-2014  07:43  (GMT-05:00) </div><div>Till: Discussion of precise time and frequency measurement <time-nuts at febo.com> </div><div>Rubrik: Re: [time-nuts] WTB: GPS Antenna Splitter </div><div>
</div>Hi,

For those with a junk basket full of generic splitter/combiners and
DC-blocks, go ahead and put something together. Note that most receivers
wish to have a DC-load of around 200ohm to not raise antenna fault alarms.

I have not found a dedicated GPS splitter cheaper than this from
Mini-Circuits

    http://217.34.103.131/pdfs/ZAPD-2DC+.pdf

When trolling the online auction sites, GPS Source and GPS Networking
splitters are often less pricy than the HP/Agilent/Symmetricom/Microsemi
ones.

--

    Björn

> Hi:
>
> This works great and has minimal cost.
> http://www.prc68.com/I/4GPS.shtml
>
> Have Fun,
>
> Brooke Clarke
> http://www.PRC68.com
> http://www.end2partygovernment.com/2012Issues.html
> http://www.prc68.com/I/DietNutrition.html
>
> John C. Westmoreland, P.E. wrote:
>> Dave,
>>
>> Can you please let us know what you go with for your splitter choice?
>>
>> I noticed companies like EndRun Technologies use ones from these folks:
>> http://gpsnetworking.com/GPS-antenna-splitters.asp
>>
>> TESSCO might stock those if you ask them.
>>
>> Regards,
>> John W.
>>
>>
>> On Mon, Oct 6, 2014 at 6:09 PM, Bob Camp <kb8tq at n1k.org> wrote:
>>
>>> Hi
>>>
>>> Missed the survey question…
>>>
>>> If a ns in free air is about 1 foot (30 cm), then you probably want a
>>> survey that is better than 6” to keep the error down. You do not want
>>> to
>>> have the antennas on top of each other, so yes, the GPS will need a
>>> survey
>>> / location each time you change antennas. If you go with the 10’
>>> spacing,
>>> then you will get some pretty big jumps without switching the location.
>>>
>>> Bob
>>>
>>> On Oct 6, 2014, at 4:01 PM, Dave M <dgminala at mediacombb.net> wrote:
>>>
>>>> Does anyone in the group have, or can point me to, a low-cost (but not
>>>> cheap) 2-port splitter for a GPS antenna?  Those on Ebay are rather
>>>> expensive.
>>>>
>>>> I have two GPSDO units, and have both an older timing antenna and a
>>>> new
>>>> choke ring antenna (Thanks, Pete L).  I already have one 2-port
>>>> splitter
>>>> (working well), but my intent is to connect both antennas through the
>>>> splitters and a couple coaxial relays so that I can, with the twist of
>>>> a
>>>> switch, allow me to run each GPS from a different antenna, or both
>>>> from
>>> the
>>>> same antenna.  I would like to gather some data as to the differences
>>>> between the two antennas.  I know I could switch the connections
>>> manually,
>>>> but I like the idea of a switch to sort of automate the connections,
>>>> and
>>> I'd
>>>> need another splitter anyway.
>>>>
>>>> Before I go to the trouble and expense of building upon this idea, are
>>> there
>>>> any comments as to the value of the project?
>>>> Some questions come to mind:
>>>> I'm thinking about mounting both antennas on the same mast, at the
>>>> same
>>>> elevation, just separated by a couple feet.  Any problems that I
>>>> should
>>> be
>>>> aware of by putting both antennas so close together?  Will that small
>>>> distance have a noticeable effect when switching a receiver from one
>>> antenna
>>>> to the other?  Will the GPS notice the difference and want to do
>>>> another
>>>> survey?
>>>>
>>>> Thanks for your comments.
>>>> Dave M
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