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.