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The first of many, many avionics questions

Desert Rat

Well Known Member
Hey guys- Like the title says, avionics are uncharted territory for me, but how hard could it be, right?

To get the ball rolling, can anybody confirm for the that if I go with a GTX45R all in one Transponder ADSB in/out box, do I just need one antenna?

If thats correct, which antenna would that be, a transponder antenna or a UAT antenna?

Looking at Delta Pop as a solution and they sell both?
 
I'm not familiar with that particular unit, but a transponder and a GPS cannot share the same antenna. And, the transponder antenna needs to be on the bottom whereas the GPS needs to be on top of the aircraft.
 
From my reading the GTX45R requires an approved GPS position source - it does not have a GPS receiver.

https://buy.garmin.com/en-US/US/p/568115

To answer your specific question, two antennas. A transponder antenna and whatever your WAAS GPS source is using for an antenna.

So, start adding up costs. This will be an expense path. There are so many better, integrated approaches for less money and more capability.

Carl
 
From my reading the GTX45R requires an approved GPS position source - it does not have a GPS receiver.

https://buy.garmin.com/en-US/US/p/568115

To answer your specific question, two antennas. A transponder antenna and whatever your WAAS GPS source is using for an antenna.

So, start adding up costs. This will be an expense path. There are so many better, integrated approaches for less money and more capability.

Carl

Starting from scratch i thought the gnx375 was the best approach. 2 antennas, one box
 
I paired my GTX45R with Garmin’s GPS 20A WAAS GPS receiver. The GTX unit required one antenna. I put it on the bottom of the aft fuselage cone. The GPS receiver required one antenna on top. The GPS unit connects to the transponder to provide ADS-B position. I installed both boxes in the tail cone behind the baggage bulkhead.
 
Have a look in the Garmin GTX 45R Installation Manual Section 3.7. It lists the specific approved brand and model XPDR antennas, and the specifications it must meet if using an antenna not on the list. I used the Comant CI-105 DME/Transponder antenna with BNC connector.
 
If thats correct, which antenna would that be, a transponder antenna or a UAT antenna?

A little misunderstanding here. There are two ways of satisfying transponder and ADSB requirements. You can:
(1) Have a mode C transponder and a UAT on 978 MHz. Two antennas.
(2) Have a mode S-ES transponder (both transponder and adsb in one signal, on 1030 MHz). One antenna.

Either way, you also need a GPS Antenna, and an "approved' gps.
The GTX45r uses method (2).
As Carl said, the (list) price of this box takes my breath away. You can save $1K or more with other choices.
 
The GTX45R only requires one antenna. I prefer the CI-105 certified antenna mounted on the bottom of the aircraft just aft of the wing to prevent any shading of the antenna from above the aircraft. In other words, under the tail cone.
 
A little misunderstanding here. There are two ways of satisfying transponder and ADSB requirements. You can:
(1) Have a mode C transponder and a UAT on 978 MHz. Two antennas.
(2) Have a mode S-ES transponder (both transponder and adsb in one signal, on 1030 MHz). One antenna.

Either way, you also need a GPS Antenna, and an "approved' gps.
The GTX45r uses method (2).
As Carl said, the (list) price of this box takes my breath away. You can save $1K or more with other choices.


So what other choices are we talking about here?

I'm looking for 2 comms, 1 nav & an IFR GPS. ADSB in/out, all piped into a G3X system. At this point I'm just thinking about antenna placement, but I'm certainly willing to learn!
 
Look at SteinAir.com under Support and FAQs. They have a diagram of an RV-7 with recommended antenna locations etc.
 
So what other choices are we talking about here?

I'm looking for 2 comms, 1 nav & an IFR GPS. ADSB in/out, all piped into a G3X system. At this point I'm just thinking about antenna placement, but I'm certainly willing to learn!
In your first post you didn’t mention the G3X. That complicates matters.
A Trig TT22 mode S-ES transponder has a street price of about $2K, and can read gps data from a Garmin GTN or older 430W. However, it won’t interface seamlessly (I don’t think) with a G3X, if that’s what your heart is set on. Likewise, you’d still need an adsb-in box, which can be had for not much, unless you want it to interface to the G3X. Then you tend to be stuck with a more expensive Garmin box.
 
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