[time-nuts] GPS antenna splitters

Brian Kirby kilodelta4foxmike at gmail.com
Fri Mar 26 21:54:13 UTC 2010


When I first got started using GPS timing receivers, I used direct 
broadcasting satellite cable splitters.  They are designed to pass DC, 
and usually good to 1.5 to 2 Ghz.

If you need amplification you can also use DBS inline amplifiers - but 
they need 12-18 volts to power them - so you would have to use a couple 
of bias tee's, one for amplifier power and another in front of the 
amplifier to provide antenna power (a lot are 5 volts - you need to 
check this).

Symmetricom made splitters that also amplified the signal, and use the 
voltage from the GPS receiver to power it.  You can usually see a 2 port 
version of this for under $50 on flea-bay.  There are also 4 port 
versions.  These are called active GPS splitters.  The amplification is 
enough to get over the splitter loss and usually no more - so you have 
to have a good signal to them.

Arthur Dent wrote:
> Dan Rae-"When I only had two gps units in the dim and distant past, I 
> used a passive splitter made from a Minicircuits (MCL) ZAPD-2 unit bought 
> at the swap meet for $1, with a 100 pF series blocking cap in one of the 
> output ports.  If the receiver connected to the other port complains, 
> you can add some resistance to ground to fool it."
>
>
> While a resistive splitter with one capacitively coupled output will 
> work fine, You can insert a simple "T" in series with the GPS that 
> will supply the power and the antenna. Then feed the other leg of the 
> "T" through a capacitor (with a 220-330 ohm resistor to ground) to the 
> second receiver-amounts to about the same thing as the splitter. Almost 
> any value capacitor around 47-100pf should work. This will at least 
> let you run both GPSDOs until you can find a better splitter/amp at a 
> reasonable price.  
>
>
>
>       
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