[time-nuts] GPS antenna splitter

Magnus Danielson magnus at rubidium.dyndns.org
Sat Jun 29 16:34:24 EDT 2013


Hi Bob,

On 06/29/2013 08:43 PM, Bob Camp wrote:
> Hi
>
> The auction sites are great sources of GPS splitters. I've gotten Mini Circuits splitters for much less than what they go for new. All of the ones I've seen do indeed pass DC.
>
> One thing to consider - you may want one with an extra port on it. Some GPS cards are a bit sensitive to antenna current. If you gang up seven receivers, one may not see enough drain to turn off the antenna alarm. The simple answer is to terminate one port with a resistor to ground.
>
> If you do need to inject DC, they make purpose built gizmos. You can also run one of the Symmetricom splitters that has DC blocking on all but one port. They tend to be expensive.

For GPS receivers needing more DC load, I've found that hooking up a DC 
load through a SMD inductor in series with a SMD resistor (150 Ohm is 
what I've used). I hacked that onto a BNC-T and it got a GPS receiver to 
work.

Strange that my hobby-hack is drive-by delivered to one of the major
telecom operators, but it solved their problems. :)

A splitter should have a pre-amplifier.

Cheers,
Magnus


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