Audio Squeal on 125.00
Printed From: Avidyne
Category: Avidyne General
Forum Name: IFD 5 Series & IFD 4 Series Touch Screen GPS/NAV/COM
Forum Description: Topics on Avidyne's IFD 5 Series and IFD 4 Series Touch Screen GPS/NAV/COM
URL: http://forums.avidyne.com/forum_posts.asp?TID=854
Printed Date: 29 Apr 2024 at 12:11am
Software Version: Web Wiz Forums 12.01 - http://www.webwizforums.com
Topic: Audio Squeal on 125.00
Posted By: Maurice
Subject: Audio Squeal on 125.00
Date Posted: 25 Oct 2015 at 10:40am
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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. |
Replies:
Posted By: oskrypuch
Date Posted: 25 Oct 2015 at 11:11am
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Do you have an ASPEN? * Orest |
Posted By: Maurice
Date Posted: 25 Oct 2015 at 11:32am
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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. |
Posted By: ac11
Date Posted: 23 Aug 2016 at 5:41am
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What was the resolution to this? Orest, why would the Aspen make a difference? |
Posted By: Maurice Gunderso
Date Posted: 23 Aug 2016 at 7:47am
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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. ------------- Maurice Gunderson M: 415-810-4559 |
Posted By: ac11
Date Posted: 24 Aug 2016 at 3:28am
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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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Posted By: oskrypuch
Date Posted: 24 Aug 2016 at 8:34am
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 |
ac11 wrote:Posted By: MarkZ
Date Posted: 24 Aug 2016 at 8:34am
| I'd like to second great service with Avidyne's staying on the issues until they are resolved. |
Posted By: tony
Date Posted: 25 Aug 2016 at 11:56am
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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. |
Posted By: pburger
Date Posted: 25 Aug 2016 at 2:41pm
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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.
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