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  #1  
Old 04-27-2017, 02:52 PM
Starlifter Starlifter is offline
 
Join Date: Aug 2016
Location: Granbury, TX
Posts: 22
Default ELT noise

I have a very high frequency, relatively faint noise emanating from my RV-7A which is associated with my Ameri-king AK-451 ELT.

I noticed it a while back (bought the airplane from the builder in 8/16 but never noticed the noise until earlier this year). I disconnected the aircraft battery in an attempt to isolate the problem but it continued. I could not figure out where the noise was coming from until it ceased when I disconnected the remote (phone style jack) cord from the ELT during it's removal upon it's failing to test.

I tested the batteries, which were installed last year by Ameri-king when the previous owner sent the unit in for repair after the unit broadcast a 406 alert while it was unattended in it's hangar and the owner was called by SAR. (yes, it turns out this was AFTER the FAA cease and desist for Ameri-king. Whole 'nother subject). Each battery tested between .29 and .36 volts.

I called Ameri-king and asked why new batteries (placarded as good until 9/20) would be dead in less than a year. No help.

I had received a spare set of batteries with the airplane so I installed them and all tested well. I reinstalled and hooked up the ELT to the remote and antenna and the friggin' noise returned. Only louder! Why not? I had new batteries in it. Make no mistake, it's still a pretty faint noise and cannot be confused with the 406 test tone.

What is this noise? I must determine what is causing it because I'm sure it's being powered by the ELT batteries and is most likely what drained them prematurely. ELT batteries are not cheap!!!

Thanks for any enlightenment.
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  #2  
Old 04-27-2017, 04:19 PM
az_gila's Avatar
az_gila az_gila is online now
 
Join Date: Jan 2005
Location: 57AZ - NW Tucson area
Posts: 8,813
Exclamation

If you are using the two-wire interconnect option from ELT to remote - check that you have good grounds to the airframe at both the ELT and at the T-adapter.

Page 64 - http://www.ameri-king.com/pdf/IM451R...ublication.pdf
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Gil Alexander
EAA Technical Counselor, Airframe Mechanic
Half completed RV-10 QB purchased
RV-6A N61GX - finally flying
Grumman Tiger N12GA - flying
La Cholla Airpark (57AZ) Tucson AZ
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  #3  
Old 04-28-2017, 09:48 AM
Starlifter Starlifter is offline
 
Join Date: Aug 2016
Location: Granbury, TX
Posts: 22
Default

Thanks. Not sure which one I have.......bought the airplane recently and this is the first time I've been into it. How far from the remote might I find the "T" and the buzzer unit? I haven't yet figured out how to get at the remote. I can see it in front of my face, but not sure how to get at it yet. Awaiting a response from the builder before I start tearing stuff out.

Thanks, again.
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  #4  
Old 04-28-2017, 02:39 PM
Starlifter Starlifter is offline
 
Join Date: Aug 2016
Location: Granbury, TX
Posts: 22
Default

Oh.....and is there a way to determine which wiring I have (2, 4, or 5) without getting to the remote or opening up the ELT case?
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  #5  
Old 04-28-2017, 02:59 PM
az_gila's Avatar
az_gila az_gila is online now
 
Join Date: Jan 2005
Location: 57AZ - NW Tucson area
Posts: 8,813
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Quote:
Originally Posted by Starlifter View Post
Oh.....and is there a way to determine which wiring I have (2, 4, or 5) without getting to the remote or opening up the ELT case?
Don't think so... you really need to inspect the wiring or get a diagram from the builder since there are so many wiring variations possible.
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Gil Alexander
EAA Technical Counselor, Airframe Mechanic
Half completed RV-10 QB purchased
RV-6A N61GX - finally flying
Grumman Tiger N12GA - flying
La Cholla Airpark (57AZ) Tucson AZ
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  #6  
Old 05-03-2017, 08:59 AM
Starlifter Starlifter is offline
 
Join Date: Aug 2016
Location: Granbury, TX
Posts: 22
Default Solved

I'm not sure exactly why, but the noise was caused by a low remote battery. Remote was installed from behind the panel (for esthetic reasons) necessitating the removal of VSI and altimeter to remove the remote. Checked the battery voltage at 2.5v. Replaced the battery and the noise did not re-appear after system re-connection.
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