Lost plane buzzer problem
 

I have 2 planes, an eflite Maule and a turbo timber.I have added a Signal Loss Alarm & Lost Plane Finder to both planes. They are added in series with the elevator servos. The Maule works great. The Turbo Timber does not. All I get from the Turbo Timber is after a minute or so is short "beep" fairly quiet which repeats every minute. It never goes to the SOS output. I tried attaching it to the receiver without the servo and see no change. So I figure it must be something to do with the esc or receiver.

Any suggestions would be appreciated