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  #1  
Old 03-21-2021, 01:01 PM
Desert Rat Desert Rat is offline
 
Join Date: Aug 2018
Location: 50-50 Wichita KS & Scottsdale AZ
Posts: 559
Default The first of many, many avionics questions

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?
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  #2  
Old 03-21-2021, 01:06 PM
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Mel Mel is offline
 
Join Date: Mar 2005
Location: Dallas area
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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.
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Mel Asberry, DAR since the last century. Over 1,000 certifications accomplished.
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  #3  
Old 03-21-2021, 01:06 PM
Jetmart Jetmart is offline
 
Join Date: Sep 2019
Location: Windsor, Ontario
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Yes just the one antenna. This is all you need.

http://www.deltapopaviation.com/Tran...r_Antenna.html
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  #4  
Old 03-21-2021, 01:44 PM
Carl Froehlich's Avatar
Carl Froehlich Carl Froehlich is offline
 
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Location: Dogwood Airpark (VA42)
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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
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  #5  
Old 03-21-2021, 01:48 PM
PilotjohnS PilotjohnS is offline
 
Join Date: Jan 2016
Location: Southwest
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Quote:
Originally Posted by Carl Froehlich View Post
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
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WARNING! Information presented in this post is my opinion. All users of info have sole responsibility for determining accuracy or suitability for their use.

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  #6  
Old 03-21-2021, 02:01 PM
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Draker Draker is offline
 
Join Date: Jun 2016
Location: Livermore, CA
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I paired my GTX45R with Garminís 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.
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  #7  
Old 03-21-2021, 03:00 PM
terrye terrye is offline
 
Join Date: Feb 2010
Location: Vancouver, BC, Canada
Posts: 931
Default The first of many, many avionics questions

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.
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  #8  
Old 03-21-2021, 04:20 PM
BobTurner BobTurner is offline
 
Join Date: Dec 2011
Location: Livermore, CA
Posts: 7,340
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Quote:
Originally Posted by Desert Rat View Post

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.
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  #9  
Old 03-21-2021, 04:37 PM
GalinHdz's Avatar
GalinHdz GalinHdz is offline
 
Join Date: Mar 2010
Location: KSGJ / TJBQ
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Quote:
Originally Posted by Carl Froehlich View Post
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.

Carl
^^^^^ THIS ^^^^^
is the answer to your question.

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  #10  
Old 03-21-2021, 06:27 PM
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Christer Christer is offline
 
Join Date: Apr 2008
Location: Webster, MN
Posts: 100
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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.
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