Audio Squeal on 125.00 |
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Maurice
Newbie Joined: 23 Feb 2015 Location: KCCR Status: Offline Points: 3 |
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Posted: 25 Oct 2015 at 10:40am |
I have an IFD540 GPS/NAV/COM and an AMX240 audio panel. Whenever I have 125.00 as the active com frequency I get a loud audio squeal. This stops when I transmit, or when someone else transmits and the "Rx" indicator comes on. In other words, the squeal happens whenever the channel is quiet.
At first I had experienced this only when I land at Palo Alto (KPAO) which uses 125.00 for ground, so I assumed it was something peculiar with KPAO's transmitters. But recently I landed at Sacramento Exec (KSAC) which also uses 125.00 for ground and it happened there too, so I now realize the problem is on my end. Has anyone else experienced this? Thanks for input and suggestions. Maurice. |
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oskrypuch
Senior Member Joined: 09 Nov 2012 Location: CYFD Status: Offline Points: 3061 |
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Do you have an ASPEN?
* Orest |
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Maurice
Newbie Joined: 23 Feb 2015 Location: KCCR Status: Offline Points: 3 |
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Orest,
Thanks for the reply. No Aspen. Most of the panel is 1982 vintage Cessna and King, including a KFC 200 Autopilot with HSI and Flight Director. I also have a Garmin 496 in an Airgizmo dock, a Horizon electronic tachometer, a yoke-mounted iPad, and a Stratus II in the back. Regards, Maurice. |
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ac11
Groupie Joined: 21 Aug 2016 Location: SF Bay Area Status: Offline Points: 98 |
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What was the resolution to this?
Orest, why would the Aspen make a difference? |
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Maurice Gunderso
Newbie Joined: 22 Feb 2015 Location: KCCR Status: Offline Points: 5 |
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AC11, thanks for reminding me to post the outcome.
After I posted the problem, I discovered that when 125.00 was tuned in the active position, and not transmitting, the loud squeal was also received on my No. 2 com (a King KX155) if it was tuned to 125.00. So that pointed to the IFD540 as the source of the interference. My avionics shop took the IFD540 out of the airplane and powered it up on the bench. Sure enough, when 125.00 was tuned in the active position, and not transmitting, the loud squeal was received on a handheld transceiver tuned to 125.00. The handheld could be 20 to 30 feet away and still pick up the squeal. This confirmed that the problem was originating in the IFD540. The avionics shop discussed this at length with Avidyne. After some more tests, Avidyne declared they had never seen this problem before and did not understand what was causing it. Avidyne sent a replacement IFD540 and had my original one sent back for diagnosis. The replacement IFD540 does not have the problem. I assume the original one is causing some head scratching at the factory. So from my standpoint, Avidyne resolved my problem quickly and satisfactorily. What could be better than swapping the unit at no charge? Whether they have now diagnosed the problem in the original unit, I don't know and may never learn. Regards, Maurice. Edited by Maurice Gunderso - 23 Aug 2016 at 7:49am |
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Maurice Gunderson
M: 415-810-4559 |
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ac11
Groupie Joined: 21 Aug 2016 Location: SF Bay Area Status: Offline Points: 98 |
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Thanks Maurice for the follow up. I'm still curious about Orest's thought process with the Aspen.
Jeff
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oskrypuch
Senior Member Joined: 09 Nov 2012 Location: CYFD Status: Offline Points: 3061 |
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So am I, that was from last year. I vaguely remember reading about an odd COM interaction on ASPEN panels, although not specific to IFDs, but can't remember the specifics now. * Orest Edited by oskrypuch - 24 Aug 2016 at 8:38am |
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MarkZ
Senior Member Joined: 05 Sep 2015 Location: 0TX0 Status: Offline Points: 172 |
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I'd like to second great service with Avidyne's staying on the issues until they are resolved.
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tony
Senior Member Joined: 06 Dec 2011 Location: Atlanta Status: Offline Points: 466 |
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Do you still have an old 121 ELT? If so remove it fro the airplane and see if the 125MHX signal is still there. |
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pburger
Senior Member Joined: 26 Dec 2013 Location: United States Status: Offline Points: 406 |
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I encountered a loud, pulsating, garbly tone or squeal on 125.0 a month ago, and then again yesterday. I first noticed it on the IFD-540, and tried my trusty KX-175B, and heard the same exact squeal.
I was able to isolate the problem yesterday. It is coming from my Stratux DIY ADS-B receiver. As soon as I powered down the Stratux, the squeal stopped on both radios. I plan to add shielding to my Stratux case to hopefully minimize the problem.
Edited by pburger - 25 Aug 2016 at 2:42pm |
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