G3X External Antenna

[PT20J]

The G3X STC requires a GPS antenna. Both the glareshield mounted and GA 56 are approved for connection to the G3X per the Maintenance Manual, but the STC only covers the glareshield antenna, so the GA 56 would require a field approval. It turns out that the GA 56 has the same mounting hole pattern as the Aspen RSM that I would be removing, and I don't fancy attaching a glareshield antenna to the flimsy Mooney glareshield. Has anyone had any experience installing a GA 56 (or other Garmin-approved airframe mounted antennas) with a G3X?

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[ArtVandelay]

Would you really need to mount antenna to the glare shield, couldn’t it be mounted just underneath, the plastic shield won’t block the gps signals?

[PT20J]

21 minutes ago, ArtVandelay said:

Would you really need to mount antenna to the glare shield, couldn’t it be mounted just underneath, the plastic shield won’t block the gps signals?

Electrically, yes. But Garmin’s STC installation instructions show it mounted on top either screwed down or with Velcro. 

[ArtVandelay]

Electrically, yes. But Garmin’s STC installation instructions show it mounted on top either screwed down or with Velcro. 

The experimental version discusses why this could be a problem for metal airplanes in certain circumstances, and preference is to have an external antenna.
I’m curious, does G500 have this issue? Seems trivial (signoff) to use whatever antenna and mounting G500 requires if it does.

[PJClark]

My G3X antenna sits in the pilot's side corner between the dash and the windscreen, attached to nothing at all. Just sits there. And works just dandy.

[ArtVandelay]

My G3X antenna sits in the pilot's side corner between the dash and the windscreen, attached to nothing at all. Just sits there. And works just dandy.

I think that antenna is only needed if panel mount gps goes belly up. You should check satellite reception on N to E headings with panel mount gps powered off, where the antenna is likely to be blocked by the fuselage.

[PJClark]

I don't think so. The G3X has a standalone GPS that's good for only VFR navigation. I'm certain it's using that antenna. You can choose the internal GPS for use as the Nav source, but of course 99% of the time or more everyone is gonna just use the certified GPS(s) in the panel

[PT20J]

I figured out the paperwork to get a GA 56 installed. The STC for the G3X approves this antenna for interface but not installation. However, Garmin has an antenna STC (SA01695SE) that includes the GA 56 and approves installation, but not the interface. So the combination of the two STCs provides approval for installation of the G3X interfaced to with a GA 56. 

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[Ragsf15e]

7 hours ago, PT20J said:

I figured out the paperwork to get a GA 56 installed. The STC for the G3X approves this antenna for interface but not installation. However, Garmin has an antenna STC (SA01695SE) that includes the GA 56 and approves installation, but not the interface. So the combination of the two STCs provides approval for installation of the G3X interfaced to with a GA 56. 

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You’re going to have to thoroughly educate your installer after all the research you’ve done!