The start button on the transmitter is a digital code within the Heng Long MFU. The 123 Electronics sound boards need analog negative pulses to trigger sounds, and that is why the start is connected to the smoker output. The smoker can still be used.if you want to, and the fact I am using the smoker to signal the engine start makes sense. Ie when you start the engine the smoker will turn on.
OK, makes sense to me now. Thanks for the education.