The Airtronics transmitter is not compatible with the Tower receicer.
The transmitter is positive shift and the receiver is negative shift. There are plenty who know what that actually means but it really does not matter since they do not work together.

You'll need an Aitronics receiver and crystal, or another brand that is compatible.
JR 72 mhz receivers are compatible with Airtronics transmitters.
Hitec makes receivers that shift selectable so they can work with either type of transmitter.
Castle Creations Berg receivers are also shift selectable so they can work with either type of transmitter.