Greg Ellis Posted May 11, 2021 Author Report Posted May 11, 2021 On 5/11/2021 at 3:46 PM, Baker Avionics said: Is your GNC300 the number 1 radio or number 2? Expand It is the #2 radio on Comm 2. Quote
Baker Avionics Posted May 11, 2021 Report Posted May 11, 2021 My questions are, what other Avionics do you have, but if you pulled all of the CB for everything else, it is a little weird. Quote
Greg Ellis Posted May 11, 2021 Author Report Posted May 11, 2021 On 5/11/2021 at 3:50 PM, chriscalandro said: What else is that unit wired to Expand Meaning the audio panel? The GMA 345 is only wired to a Garmin GNS 530W on Comm 1 and a GNC300XL on Comm 2. No other radios or Nav units. Quote
Greg Ellis Posted May 11, 2021 Author Report Posted May 11, 2021 On 5/11/2021 at 3:52 PM, Baker Avionics said: My questions are, what other Avionics do you have, but if you pulled all of the CB for everything else, it is a little weird. Expand So, I have a 530W, the 300XL, a G5, the GMA 345, a GTX 345 transponder, and a JPI 900. No autopilot, no other nav or comm radios. Quote
chriscalandro Posted May 11, 2021 Report Posted May 11, 2021 On 5/11/2021 at 3:53 PM, Greg Ellis said: Meaning the audio panel? The GMA 345 is only wired to a Garmin GNS 530W on Comm 1 and a GNC300XL on Comm 2. No other radios or Nav units. Expand well it sounds a lot like crosstalk between a data bus, either serial, arinc, or other into the audio circuit. It could be internal, it could be a wire, it could be a large number of things. Are they standard density pins on the back of that unit? Should be easy enough to troubleshoot by pulling some pins that aren't power related or audio panel related and see what you get. Quote
Greg Ellis Posted May 11, 2021 Author Report Posted May 11, 2021 On 5/11/2021 at 4:48 PM, chriscalandro said: well it sounds a lot like crosstalk between a data bus, either serial, arinc, or other into the audio circuit. It could be internal, it could be a wire, it could be a large number of things. Are they standard density pins on the back of that unit? Should be easy enough to troubleshoot by pulling some pins that aren't power related or audio panel related and see what you get. Expand Thanks for the information and I will pass this along to the avionics guys working on it. Not sure about the pins on the unit. Quote
Baker Avionics Posted May 11, 2021 Report Posted May 11, 2021 I would look at the shielding or the shield ground going to the same ground as the power. whether you look at the GNC300 or the Audio Panel. It seems like that to me. Quote
MikeOH Posted May 12, 2021 Report Posted May 12, 2021 At this point, I would pull the GNC300XL out of the panel and run it on the bench with an external power supply with only a speaker hooked up; no antenna or anything else but the speaker. That would prove if the GNC is the source, or if it is external interference. Quote
MikeOH Posted May 12, 2021 Report Posted May 12, 2021 Other random thoughts... Did this problem just start, or is this a new install problem? (Sorry, if that's been covered) Does this happen everywhere? As in, at other airports, in the air, or just at your home airport? The fact that the #1 comm doesn't have the issue suggests (but does NOT prove) that the problem is either poor shielding (as Greg Baker suggests), or that it is internal to the unit itself. Quote
Greg Ellis Posted May 12, 2021 Author Report Posted May 12, 2021 On 5/12/2021 at 1:50 AM, MikeOH said: At this point, I would pull the GNC300XL out of the panel and run it on the bench with an external power supply with only a speaker hooked up; no antenna or anything else but the speaker. That would prove if the GNC is the source, or if it is external interference. Expand That's a great idea. I will pass this along. Thanks. Quote
Greg Ellis Posted May 12, 2021 Author Report Posted May 12, 2021 On 5/11/2021 at 11:04 PM, Baker Avionics said: I would look at the shielding or the shield ground going to the same ground as the power. whether you look at the GNC300 or the Audio Panel. It seems like that to me. Expand I passed the info along regarding the shielding. I appreciate your help with this. Quote
Greg Ellis Posted May 12, 2021 Author Report Posted May 12, 2021 On 5/12/2021 at 1:59 AM, MikeOH said: Other random thoughts... Did this problem just start, or is this a new install problem? (Sorry, if that's been covered) Does this happen everywhere? As in, at other airports, in the air, or just at your home airport? The fact that the #1 comm doesn't have the issue suggests (but does NOT prove) that the problem is either poor shielding (as Greg Baker suggests), or that it is internal to the unit itself. Expand It is not a new problem and has been happening for a while. It does occur everywhere. I have switched the GNC300XL out with another GNC300 that I have and it still happens. The shop has a GNC300 that they were going to put in an try as well. Thanks for your response. I am passing along all of this information to the shop. I don't think they have had a chance to look at it. They have been very busy. They were going to try to get to it this week but I leave tomorrow for the Mooney Caravan clinic and was hoping they would solve it before I leave. Quote
Greg Ellis Posted July 14, 2021 Author Report Posted July 14, 2021 Some of you are aware and have provided excellent advice on how to solve this ongoing issue of the repetitive noise I have through my #2 comm. To review, my avionics shop checked all the wiring again, they installed a different #2 GNC 300XL to see if it was my GNC 300XL. They took out my GMA 345 and put a new one in to see if it was my audio panel, they checked all coax cables, all grounds, even went back and forth with Garmin multiple times. Nothing worked. I was getting tired of not having my airplane around when I wanted it and not having quality radios that were quiet. So, getting tired of this I figured, hey, money can usually solve airplane issues so I threw a little, well a lot more money at the problem. I had them remove the GNC 300XL and all its components like the tray and wiring etc... I had them install a Garmin GNC 355. Viola....all noise is gone, everything is quiet and the radio sounds great. So I wish I had something really cool to report but according to Garmin, there was something about the actual tray that the GNC 300XL sits in and the connectors at the back that was causing the issue and that is why a different GNC 300XL did not solve the problem. It took a more modern GPS install to solve the problem. I am just happy that I no longer have to listen to that awful noise on the #2 radio and I can now start putting money towards the GFC500 Autopilot!!!! Thanks for any and all advice from the group. 3 Quote
carusoam Posted July 15, 2021 Report Posted July 15, 2021 Fantastic follow-up Greg! Best regards, -a- Quote
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