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GTN650/G3X dual comm ?

543TB

Well Known Member
So, having spent a few hours searching the G3X install manual and searching online, I am still unsure about what capabilities the system has. I would like a minimalist panel and the original plan was to install just the GTN 625 for GPS but since legal IFR requires a backup navigation source, it looks like I'll be ordering the 650 instead. What I cannot tell is whether or not I can utilize the GTR 20 as the remote intercom/audio panel & com 1 radio while also including the GTN 650 as an additional com radio without needing to run it through an external panel like the GMA 240. None of the installation drawings show this combination, but has anyone out there successfully done this? Can I just run the GTN through the GAD 29 and the GDU460 and designate it com 2 while putting the GTR 20 on the CAN bus?
 
I would like a minimalist panel and the original plan was to install just the GTN 625 for GPS but since legal IFR requires a backup navigation source,

The above statement is not true in the US (it is true for the older TSO129 (non-WAAS) boxes).

Whether having just one nav source is wise, is another topic.
 
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The gtr 200 or 20 both have an internal comm panel. I have a gtr 200 as primary comm, gx60 as backup comm and gps, gtn 625 primary nav, and Val nav2000 for radio navigation. About as cheap and redundant as I could get and have the ability to do everything. I don't have a 650 so I can't speak to that part of it, but the 650 wouldn't be on the can bus at all, outside of the info coming from it via the gad 29.

You absolutely can run the 650 com piece through the gtr20 without an audio panel. You would need to wire in a DPDT switch to switch between which radio you transmitted on. Again, this is how I did mine so no external comment panel is required.
 
I also followed this path. In my case, it was a 420W gps/com and an SL30 nav/com. While the 650 gives you gps and vor/ils, it's not really fail-safe as a back up. If the one box fails, you may lose both navigation functions.

That said, I know some have gone with one TSO'd gps box, and hope they can use a hand-held device like an iPad or portable VOR receiver if that one box fails.
 
So, having spent a few hours searching the G3X install manual and searching online, I am still unsure about what capabilities the system has. I would like a minimalist panel and the original plan was to install just the GTN 625 for GPS but since legal IFR requires a backup navigation source, it looks like I'll be ordering the 650 instead. What I cannot tell is whether or not I can utilize the GTR 20 as the remote intercom/audio panel & com 1 radio while also including the GTN 650 as an additional com radio without needing to run it through an external panel like the GMA 240. None of the installation drawings show this combination, but has anyone out there successfully done this? Can I just run the GTN through the GAD 29 and the GDU460 and designate it com 2 while putting the GTR 20 on the CAN bus?

Garmin does make a remote audio panel for you to consider. When I add my GTN625/35 to my G3X system, I will also install the GMA245R to integrate the existing GTR20. The Bluetooth functionality seals the deal for me.
 
Garmin does make a remote audio panel for you to consider. When I add my GTN625/35 to my G3X system, I will also install the GMA245R to integrate the existing GTR20. The Bluetooth functionality seals the deal for me.

Thank you! That might be the solution I'm looking for though it sounds like I can do without an additional box.
To everyone else, thank you for your replies. I had neglected the WAAS distinction on the GPS, which is TSO'd in the case of the GTN series. I still think the NAV radio might be beneficial but I'm on the fence.

I appreciate that there are many viewpoints on this issue of IFR equipment. At my day job, I do see an occasional GPS signal failure, often NOTAM'd but not always, especially in the New Mexico area or in the mountains, so my primary concern would be that and having a ground-based backup, rather than whole unit failure. The WX in Colorado where the plane will spend the majority of time is such that if it is actually IMC it is typically also icing conditions and therefore no place for an RV. Even if we were to be hard IFR for considerable time the aircraft will still be equipped with redundant VFR GPS antenna for the G3X which ought to be enough to assist getting down and clear in an emergency. Plus someday we might get crazy and take it out of country so the ground-based NAVAID need might come into play. Who knows. All I can say is that picking out a panel is hard work!
 
All I can say is that picking out a panel is hard work!

Yes it is. These forums are full of posts from frustrated panel designers who just found out that their brand x adsb-in won't interface with their brand y efis, etc.
 
In the case of the 625 vs 650 I elected to do the g3x deal $5500 vs $8600 for the gtn 625 then spend $1k on the Val nav. Separate boxes and both can technically display the VOR/localizer on their independent screens even if the g3x and G5 crapped out, or the connection was lost or whatever the failure mode may be. Though it does use up more panel space this way, it was cheaper and provides all of the same capability. Do your homework and play with Xpanel to get a feel for what you're wanting.
 
In the case of the 625 vs 650 I elected to do the g3x deal $5500 vs $8600 for the gtn 625 then spend $1k on the Val nav. Separate boxes and both can technically display the VOR/localizer on their independent screens even if the g3x and G5 crapped out, or the connection was lost or whatever the failure mode may be. Though it does use up more panel space this way, it was cheaper and provides all of the same capability. Do your homework and play with Xpanel to get a feel for what you're wanting.

Shane - Would you mind sharing a photo of your panel?
 
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