Futaba servo rotation is opposite to other brands, so for compatibility the throttle channel must
be set to Reverse. It will then put out a 'normal' throttle signal, which is what most ESCs require. Once you have set the throttle channel to Reverse in the tx, everything else should then work normally (the only exception being that the throttle channel will appear to be 'upside down' in the servo monitor screen).
NOTE: You must only reverse the throttle channel in the REVERSE screen (separate settings for each model). Do not
activate THR-REV in the global TX SETTING screen!
Before calibrating the tx sticks in the Naza, make sure the tx's channel endpoints are all set to 100%, subtrims set to 0, and trims centered. Use the tx servo monitor screen to check that the throttle indicator goes down
as the stick is pushed up, and has the correct throw. Then re-bind the receiver with the tx throttle stick down. Finally, recalibrate each ESC's throttle range in the usual manner (start with throttle stick full up, wait for two beeps, lower throttle and wait for arming beeps).
So I plugged the Naza into my computer and ran the "Tx calibration" function but because the throttle channel was reversed, the throttle slider in the Naza Assistant software moved opposite.
I am not familiar with the Naza Assistant, but this doesn't sound right to me. When a Futaba throttle is set to Reverse, it is actually putting out a normal signal. Therefore the Naza throttle calibration should respond normally (low throttle = indicator towards the left) when its reversing button is set to Normal.