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  #1  
Old 08-11-2018, 12:55 PM
Timberwolf Timberwolf is offline
 
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Location: Navarre, FL
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Default Garmin Transponder Hookup

Garmin does a phenomenal job of putting out schematics for all things experimental....except transponder interfaces. I figured that one out the hard way installing a GTX 345 in with a G3X system and GTN650.

I'm now installing a GTX35R in my -6 with a G3X and GTN 625, but the have again noticed the literature is lacking. The schematics show only what to hookup for a 45R, but I can't find anywhere that it explains where the control for the unit comes from. I've deduced I'll need the following, if anyone can verify it would be greatly appreciated.

RS-232 connection to GSU25 (Encoder info)
RS-232 connection to GDU 4xx ( I assume that with it configurd to Connext 57600 Baud this is used to actually control the transponder, though it never says that anywhere...it just says ADSB traffic/weather which isn't applicable to the 35R)
Ethernet connection to GTN 625 (out 3A/3B) Provides GPS position

However I can assume no connection needed to GTN625 Ethernet IN 3A/3B.....or are these connected for TIS-A traffic?
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  #2  
Old 08-11-2018, 01:10 PM
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BoilermakerRV BoilermakerRV is offline
 
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Timberworlf,

Are you using the G3X installation manual? Have you downloaded the GTX35R/45R Installation Manual (link)? I have found it to be very helpful.
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  #3  
Old 08-11-2018, 01:20 PM
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Check out page 27-26 of rev AF of the G3X install manual.
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Last edited by Brantel : 08-11-2018 at 03:28 PM.
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  #4  
Old 08-11-2018, 01:41 PM
Timberwolf Timberwolf is offline
 
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Location: Navarre, FL
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The 35R/45R manual only alludes to the connections for the 45R which includes the ADSB traveling back into the GDUXXX, even though in all the drawings it says "Connext traffic/weather Data". None of the schematics in this manual show Single 35R with single GTN 6XX.

27-26 of the AF is where I deduced that the Connext is what is being used to control the input of squawk into the transponder, etc. However look at the very last one on the same page. It shows for 345/345R/45R ONLY. Not clarifying what is required for 35R only as it does not pass any ADSB weather info back to the 625.

I don't believe the 625 needs the ethernet "IN" connection as shown, just the out for GPS position info supplied to the transponder
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  #5  
Old 08-11-2018, 02:29 PM
ScaniaRV ScaniaRV is offline
 
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Please check out 26.14.3.1 in the G3X installation manual. Transponder control is through GSU 25 RS-232 channel 3.
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  #6  
Old 08-11-2018, 03:12 PM
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g3xpert g3xpert is offline
 
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Quote:
Originally Posted by Timberwolf View Post
Garmin does a phenomenal job of putting out schematics for all things experimental....except transponder interfaces. I figured that one out the hard way installing a GTX 345 in with a G3X system and GTN650.

I'm now installing a GTX35R in my -6 with a G3X and GTN 625, but the have again noticed the literature is lacking. The schematics show only what to hookup for a 45R, but I can't find anywhere that it explains where the control for the unit comes from. I've deduced I'll need the following, if anyone can verify it would be greatly appreciated.

RS-232 connection to GSU25 (Encoder info)
RS-232 connection to GDU 4xx ( I assume that with it configurd to Connext 57600 Baud this is used to actually control the transponder, though it never says that anywhere...it just says ADSB traffic/weather which isn't applicable to the 35R)
Ethernet connection to GTN 625 (out 3A/3B) Provides GPS position

However I can assume no connection needed to GTN625 Ethernet IN 3A/3B.....or are these connected for TIS-A traffic?
Hello Shane,

Please look at pages 27-26 and 27-27 of the Rev. AF G3X Installation Manual. It shows you everything you need to know to wire a GTX 35R to your equipment.

As shown on these drawing you need 2 RS-232 connections:
1. RS-232 connection between GSU 25 and GTX 35R which provides altitude data and transponder control, and also provides TIS-A data to all the GDU 4XX displays in the system if you decide to use TIS-A (most do not since ADS-B traffic is so good).
2. RS-232 connection between GTN and GTX 35R to provide GPS position data to the GTX 35R.

As noted on page 27-26, the Ethernet connection to the GTN is only used on the GTX 345/345R/45R models that have a built-in ADS-B receiver. There is no Ethernet interface on the GTX 335/335R/35R transponders.

The single ARINC 429 transmitter on the GTX 35R is automatically configured to output TIS-A traffic when TIS-A traffic is enabled, but currently only the GNS series units will receive TIS-A traffic in this manner (not the GTN).

We are not aware of any way to send TIS-A traffic to the GTN from a GTX 35R. Since we recommend that TIS-A be disabled on the transponder when an ADS-B receiver is installed (to keep things simple), there is seldom a reason to enable TIS-A in these systems. As mentioned above, TIS-A traffic is available for display on all the GDU 37X/4XX displays if anyone wants to enable and use it.

All of the wiring guidance for a GTX 345/345R/45R with G3X and GTN is provided on a single page, 27-25.

Please let us know if you have additional questions.

Thanks,
Steve
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Last edited by g3xpert : 08-11-2018 at 05:09 PM.
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  #7  
Old 08-12-2018, 08:25 AM
Timberwolf Timberwolf is offline
 
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Location: Navarre, FL
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Steve and others, thanks for the clarification.
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