GNC-215 Audio Quality

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ultrarunner

Filing Flight Plan
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ultrarunner
I've just had a new GNC-215 installed to replace an old MX-11 and add a nav radio. I was initially pretty excited, given the somewhat poor reputation that the MX-11s seem to have. Unfortunately, as much as I'd like to deny it the new Garmin radio just sounds muddy and muffled. I find myself switching to COM 2, the remaining MX-11, which is significantly crisper sounding.

I'm going to have my installer double check the harness, but part of me wonders if there's anything wrong at all.

Anyone else upgrade to the GNC-215 and have any feedback?
 
It works fine for us. Our avionics shop insists on new cables for everything. We also got a new Garmin audio panel. It’s cleaner sounding then the old 225XL.
 
My GNC-215 sounds great. I'm not sure your issue is with that unit. Concur that if both radios (old and new) in that position sounded "muddy", you probably want to check the common factors, be it wires or connectors.
 
Probably needs a new cable to the antenna. I just installed a GTR205 in my Duke, and re-used the existing coax due to the complexity of re-running new coax to the antenna location. I'm having a similar issue; the reception quality is meh, but I'm nearly certain its just the coax. I'll end up running new at some point.
 
I have the GTR205 and it works great, I’d guess that you’d want new wiring and antennas if you’re already getting a new piece of equipment.
 
When I had my panel work done, had an issue with my old radio, and it turned out to be the old connector between the cable and the unit. As others have mentioned, have them install new cable AND new cable to unit connectors.
 
IMO, buying a new radio and not doing new coax (and preferably new cabling to the audio panel) is like buying a new car but transferring the interior from your old car. Replace everything. "Buy once, cry once" as they say.
 
Well, went through an RMA and a whole new unit from Garmin, but same situation. The old MX-11 in COM 2 still sounds a whole lot better. I was hopeful, because on one 110° day the radio sounded pretty clear for a bit, but was back to being muddy and flat a 30 minute flight later.

New com wiring, made a test harness to go directly to a new Bose headset, swapped antennas, new coax, ran new grounds (even though there is zero common-mode noise on the intercom) and I'm at a loss. I once flew a different plane with a 430W as com 1 that I thought sounded like garbage, but I figured it was just due to being 20+ years old. Maybe Garmin radios are just not great? I guess I'll inline a high pass filter and live with it. I can't see myself ever buying anything Garmin again, though.

If anyone in the Phoenix area has a GNC-215 that you'd let me listen to for comparison, shoot me a PM and I'd be happy to fly to you.
 
Find an avionics shop that has a COM/NAV tester (an IFR-4000, for example). Use it to generate a 1000 Hz test tone on a few different frequencies, slowly decrease the signal strength while listening (and comparing the quality) on both radios. With the test set 10-15 feet from the aircraft, both of them should break squelch at -30dBm or better. If the Garmin needs significantly more signal to break squelch compared to the MX-11, you have an antenna problem. If it breaks squelch at the same level, but sounds muffled, you have an audio wiring problem.
My experience with sound quality for Garmin radios has been positive, so I suspect you have an installation issue.

Either that or you're talking to Michael Winslow. Are you having trouble with the radar?
 
ultrarunner said:
Maybe Garmin radios are just not great? I guess I'll inline a high pass filter and live with it. I can't see myself ever buying anything Garmin again, though.
Click to expand...

Logically, if most other owners have good results with Garmin radios, and you have bad results with two different units, the problem lies with your aircraft or installation, not with Garmin.
 
Any new radio should be installed with new wire, new coax, and a new push-pull circuit breaker. If it's not, your installer is failing you.
 
Hey, I know this is a very old post. But I'm having the same problem with my GNC 215. My old KX175B had better quality. But my intercom feature sounds crystal clear. I was wondering what was done to resolve the problem.
 
From the sales brochure: "pilot-selectable 25 kHz or 8.33 kHz channel spacing".

Sound to me like you're listening to a standard (25 kHz) transmission but the radio is tuned to a narrow (8.33 kHz) channel. Read the manual and ensure you are on the correct channel spacing.
 
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