Hi One subtle advantage of the simple satellite splitters - F connector based DC blocks are dirt cheap ….
Bob > On Jun 18, 2017, at 4:06 PM, [email protected] wrote: > > +1 for satellite splitters as a low cost option. But as others have > mentioned, you do need to use a little care. Some are 'DC isolated', but that > can mean diode OR’ing for each port (all ports DC pass) and not a DC block. > And they often don’t have the frequency response (many satellite splitters > only say 1GHz or 1500MHz). > > The Radio Shack 4 way splitter I started with was just such a device. One > input, four outputs, DC pass on all ports with diode isolation. It worked OK, > as long as all GPS were 5V antenna types. Adding a 12V receiver was suddenly > a problem as my antenna is 5V, along with the other receivers. > > The best satellite splitter choice (for me) was a DirecTV SWIM 4 way unit. > It’s rated 2-2150, has DC pass on one port. So I could connect my somewhat > deaf 12V receiver with an inline amp on one of the DC block ports, and a 5V > unit on the DC pass port. Each receiver was happy. A picture of one is at > <https://images-na.ssl-images-amazon.com/images/I/41EWn-NoJlL.jpg > <https://images-na.ssl-images-amazon.com/images/I/41EWn-NoJlL.jpg>> Easily > found and cheap, 2, 4, or 8 port models exist. > > BTW, putting each splitter on the network analyzer proved that the DirecTV > unit had lower loss and better port to port isolation than the Radio Shack > unit (no surprise really). I ran this way for quite a while until I uh… ran > out of ports. I now have a GPS Networking 8 way with ‘proper’ DC block and > load on each port which works well too. > > Just as an aside, does anyone have any thoughts on the noise contribution of > the diodes in the Radio Shack splitter (or similar)? It’s device dependent of > course, but I wonder if it’s enough to be a ‘significant’ contributor. > > Paul > >> On Jun 17, 2017, at 12:07 PM, Chris Albertson <[email protected]> >> wrote: >> >> On Fri, Jun 16, 2017 at 8:54 PM, Clay Autery <[email protected]> wrote: >> >>> This brings up some interesting questions: >>> >>> >>> I am assuming since this is a receive only situation, it will follow >>> approximately the same rules of physics that dealing with satellite >>> antenna installations. >>> >> >> And guess what? Satellite TV splitters work. They even have the answer to >> "how much attenuation" printed right on the splitter and they come with F >> type connecters you can use the recommended TV type antenna cable too. >> You can buy them with DC blockers too. All this stuff is low cost because >> it is mass produced by the billions >> >> Yes, it's 75 ohm not 50 and the splitters a 2+ GHz but it works just fine >> if your antenna has the right gain. The splitters don't high pass the >> signal. Trimble actually recommends using the 75 Ohm TV cable and >> supplies it with their kits. >> >> Sometimes a GPS receiver will raise an "Antenna Alarm" if it does not see a >> DC load but you can turn those off with a serial command >> -- >> >> Chris Albertson >> Redondo Beach, California >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
