Avionics upgrades

mandm

mandm

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Michael
Hi there, I have an older Garmin GNC300XL and wondering if there are any upgrade options that take advantage of the old installation to make an easier upgrade path? Or if any avionics is basically a full new job?

Also any recommendations for panel moving map displays?
 
mandm said:
Hi there, I have an older Garmin GNC300XL and wondering if there are any upgrade options that take advantage of the old installation to make an easier upgrade path? Or if any avionics is basically a full new job?

Also any recommendations for panel moving map displays?
Click to expand...
GNC300XL is a 2 inch GPS+COM(no VOR/LOC). GNC355 is a 2 inch GPS+COM (no VOR/LOC). Harnesses wil be different (maybe your shop can build an adapter?) and you'll need a WAAS antenna, though.
 
asicer said:
GNC300XL is a 2 inch GPS+COM(no VOR/LOC). GNC355 is a 2 inch GPS+COM (no VOR/LOC). Harnesses wil be different (maybe your shop can build an adapter?) and you'll need a WAAS antenna, though.
Click to expand...

Is Waas antenna different than the GPS antenna or just swap out the existing gps antenna for a Waas enabled antenna?
 
I am getting ready to do the 300XL to GNC355 upgrade in my RV-7A. Remove and replace is the only way.
If you don't already have an ARINC 429 unit, you will need one for the 355.
The new unit is a lot longer than the 300XL so behind the panel work is required.
The new antenna has a TNC (threaded) connector vs the old antenna with a BNC (bayonette) connector.
 
mandm said:
Is Waas antenna different than the GPS antenna or just swap out the existing gps antenna for a Waas enabled antenna?
Click to expand...

Its a different antenna. The antenna will need replacement and it’s cabling might also need to be replaced to do an install in accordance with the manual.

I don’t think you’d save much by trying to salvage the current wiring and reuse it for a new install, although the wiring going to the audio panel for the com radio could probably be reused if it is still in decent shape.
 
I have the same GPS and it’s basically a new job, in your words, even with the 355, which is the route I’m taking.

As I posted elsewhere I started looking at replacing the 300XL since it’s getting very long in the tooth, although it’s working perfectly well. It’s not even close to a slide-in replacement, unfortunately.

Aside from questions about antennae and coax (the 300XL isn’t WAAS), the indicator needs to be replaced as well. “Basic” ones are $3K, so I looked at an Aspen. Then a G5. Then a GI 275. Then two 275s, so they can drive my Piper AP and I can dump the vac system. That’s where I am now.

There’s no cheap way to move past the 300XL that I’ve found. That said, I had a Garmin 396 in the panel, fed by the 300XL since 2008 and it was great. Even better now that I swapped an Aera 660 for the 396. And a GDL50 on the dash for traffic, weather, and AHARS on the 660.

So depending on your goals, you may consider keeping the 300XL and making it a “color moving map” with a 660 and GDL50.
 
mandm said:
Is Waas antenna different than the GPS antenna or just swap out the existing gps antenna for a Waas enabled antenna?
Click to expand...
"Different" meaning "in addition to"? No. It takes the place of the existing GPS antenna. But as others have said, the existing wiring may need to be replaced.
Llewtrah381 said:
Aside from questions about antennae and coax (the 300XL isn’t WAAS), the indicator needs to be replaced as well.
Click to expand...
That would depend on the make/model of the existing indicator. The biggest factor is whether it can indicate vertical deviation as well as lateral. Beyond that, there are multiple ways to interface to it and therefore a number of compatible units.
 
asicer said:
The biggest factor is whether it can indicate vertical deviation as well as lateral. Beyond that, there are multiple ways to interface to it and therefore a number of compatible units.
Click to expand...
OK - for argument’s sake, in the very unlikely case he has an indicator for his non-WAAS 300XL that can show vertical guidance he can’t currently receive, he may be able to use it. Or he can use his current one and not benefit from having a 355’s WAAS capability.

Let me rephrase: “You MAY want to change indicators: for me and my objectives, I’m opting to”.
 
Llewtrah381 said:
in the very unlikely case he has an indicator for his non-WAAS 300XL that can show vertical guidance he can’t currently receive, he may be able to use it.
Click to expand...
Believe it or not, the reason I mentioned it is because I once flew a plane that had a GX55 (an IFR GPS that isn't even approved for approaches) that was connected to a GI106. Go figure.:crazy:
 
Concerning the indicator, plan on replacing it. The GNC355 (and other similar gps units) have a list of compatible indicators in the installation manual to choose from. But, that said, I wouldn’t install anything older than a GI-106 indicator. I have had a rather poor experience trying to interface them with some of the old King units, plus there are some quirks to them. The GI-106 indicator just seems to work and are easily found in the used market since everyone is pulling them out and going with glass. Of course, a G5 or GI-275 is also an option if you wanted to spend more.
 
I bought a used Collins IND-351 for $300 from a guy on a FB group when I installed my GPS-175 a couple years ago and it's been flawless.
 
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