Make sure the receive audio deviation is set properly on the FC or the radio, if there is one connected to the FC. I had problem with one of FC like that. There is no delay on a transmitter. The only thing that would cause a delay would be the encoder for the tones. Where is the FC located? Inside o...

Technically, you don't have to narrow band the receiver. The receiver will decode the tones just fine. I just installed a FCH and the tones are sent over fire repeater which is narrow banded. The siren activates every time! Blake