So, the funny thing about pre-planning avionics installations…. you never remember what you planned if you don’t write it down really clearly somewhere. I had a wonderful plan, but I forgot a bunch of it and ended up wasting a bunch of time. Shame on me.

So, first thing, I had originally planned for a 430. Along the way, I figured, ‘hey, they’re the same size, and the cost is about the same, and I really like the 650’s screen and interface a lot better, so I’ll do that instead’. I thought I’d swapped the GNS430 tray for the GTN650 when I built the current panel, but nope! That’s the first freak-out moment. Getting the mounting holes for these trays was a pain with the panel on the bench, much less installed. Crap. Well, as Duane says, don’t get mad, fix it, so I took the mounting screws out, and I can’t get the tray to budge. I mean, it’s really in there. Now what?

Well, got a dead-blow hammer and a flat-head screwdriver (always the right too, mind you!), and gave it a couple of love taps from behind. No joy. OK…. try the same from the front, and it scoots about 1/2″. OK, there’s NO ROOM to tak it out from behind, but it will go that way, it’s not welded (and the screws are, in fact, all of the way out). That’s good data to have. Enter bearing grease. Hey, I bought it, might as well get some mileage… I lubed up the now-visible edges of the mounting, around the back, and a couple of good taps… a little movement, so I reared back and gave it a couple of sound blows, and out she came. After a few minutes of inspection, it also became clear the mounting holes where in the exact same locations as the 650. Score!

Once the tray was in, I started looking at the wiring. Here’s where things really went astray. I thought I needed to get to my VP-x, so I started removing stuff so I could get to the connectors. First the GRT screens came out, but that left the ADI in the way, so out it came. Then, after some hand-scraping contortions I was able to get the VP-x power plug out, only to discover (2 hours of futzing around) that I had already installed those connectors. Ah… yea… kind of remember that… but where do they go??… dig out the wiring schematics… a bit later I was able to remind myself, yea, so those go to the cannon plugs that allow the panel to be removed. Makes nothing but sense, but had escaped me. So, another hour later I’d connected up all of the wires from the radio to this cannon plug (except the remote screen dimming input, haven’t decided if I’m going to hook that one up, but suffice it to say I hadn’t prewired a connection for that), and power up, and….. {nothing}… cue the disappointed look.

Well, that’s odd. Let’s start the futzing music again. Maybe it’s the tray, not seating far enough? Remove the radio, and detach the back plate… plug the radio into disembodied backtray… no joy… well, maybe it’s not getting power…. disconnect the cannon plug, get meter, check for voltage… yes, good voltage on both comm and nav pins… k… connect cannon plug, check at back plate… yes, it has power too… k… reconnect radio to back plate…. no joy… what?!… start to scratch head…

Here’s where experience starts to come into play. You may recall I learned a harsh lesson about the VP-X awhile back, and how when an output is off it’s not really “off” (it bleeds through a bit), and when the whole box is off, it allows current to pass through. Hmmm…. I wonder…. I couldn’t recall what state I’d left these outputs in within the VP-X configuration. I wondered if they were inactive, but just bleeding some voltage, but not passing any amps? I grabbed a laptop (why, no, no I didn’t bring a laptop to the airport, I had to go and get one, why do you ask?) to check the configuration. Oh, and, YEA, the VP-X had a required firmware upgrade before the laptop could connect to it, and OH YEA, I have to walk to the FBO to get an internet connection to download that, take it back, and update the firmware… tick… tick… tock…

To make a long story somewhat manageable, it turns out that, yes, I had left these outputs inactive, and once activated the 650 dutifully powered up. Very nice. As far as configuring the GRT to talk to it, and vice versa, there’s a lot of settings. Not that intuitive…. I think I’ve got it all handled now, but I’ve set the 650 to be GPS1 on the GRT, and GRT RAIM to be the backup. I think that makes me legal to fly GPS primary nav enroute on the GRT. I can also pull a flight plan from the 650 of course. I have the AIRINC configured, and the analog flags, the 650 can set my 330 transponder (not sure why I’d do that, actually, but fun)… I moved the SL20 to COM2 in the GRT (since Tim moved it physically to Com2 on the audio panel wiring… grrr…), and all seems well. I put it all back together, and went out to check the GPS signal.

That’s all good, so now I just need to get some BNC-to-TNC (male to female) adapters so I can connect my antenna wires. I put BNC on mine because I thought that was convention, and it’s what my SL30 needs, so this will allow me to still swap those if need-be. They should be in soon, and I can check out the radio side. All and all I spent more than a day fiddling with this install that I thought would be about an hour, certainly not more than 2. Ah the joys of airplane ownership…

UPDATE: So, last night I got my adapters and headed to the airport. The good news – the radio seems to work great, and I can’t wait to fly it (it was rainy and overcast last night). The bad news – I didn’t need those adapters after all. I’d only pulled the one cap off the GPS, which had the TNC style connector, so I ordered a cable from Tim at Approach. Turns out the other two, NAV and COM had standard BNC connectors. Who knows why, but I wanted to correct the record for those that follow…. odd….

Posted By: Brett Ferrell
Sunday September 7th, 2014 at 10:30 PM

Categories: Avionics
Tags: Avionics Building Garmin GPS GTN650 Vertical Power

One response to “GTN-650 WAAS Navigator Installation”

  1. Document says:

    […] Work has been eating my lunch lately, but I did get this year’s condition inspection over the last couple of weekends, as well as mounting my new GTN-650. Having the Approach Fast Stack really made that pretty straightforward, although there is a fair amount of setup to do in the GRT to get it fully communicating. Look for the full posting┬áhere. […]

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