I have come across some stuff on a US site about this but it didn’t make a lot of sense so I wondered if anyone has tried it.
All the antennae in GA avionics use are active i.e. they contain an amplifier which is powered from 5V sent up the coax cable. Typical current draw is c. 30mA.
Without this 5V, the antenna output will be basically nothing (although there may be a weak output).
You cannot have both GPSs joined up in parallel because
But it could be done with two diodes, so either GPS could supply the 5V… A schottky diode will drop ~ 0.2V at such low currents.
It works with this antenna coupler: Aero Antenna Technology, Inc., part number. PD2ORG. It is TSO’d to C129a.
This is used to install the LYNX NGT9000+ without having to install another GPS antenna. It can use of the existing GPS antennas. The coupler will pass the voltage to the antenna from whichever system is producing a higher voltage. If one system fails for any reason, the other system will be able to power the antenna and continue operation.
It is also possible to use a splitter, with the disadvantage that both devices will not work if one of them fails.
Some installers use this one: http://www.edmo.com/index.php?route=product/product&product_id=504677&search=LDCBS1X2-BNC
PS: Unfortunately that coupler costs $ 1500.00 plus VAT
Edit: Another source say that the PD2ORG is only $ 400 and available here: http://www.vfdsamsung.com/antenna.html
Interesting; thanks. Curiously, I can’t find a data sheet on a PD2ORG. Your two URLs above are the same.
Sorry, now the second link is correct.
That part is hard to find, but the product manager from L3 told me that this is the right part to install the LYNX NGT9000+ with an existing antenna.
