You may or may not be loosing a signal at 75 feet. To rule out your radio and receiver, disconnect the fail safe (take it completely out of the equation) and then operate the truck. If its range seems to be as it should be then you’ll know it is something in the fail safe.

If it is the fail safe causing the problem..........have you set the desired parameters? If not, you need to.

If the fail safe isn’t causing the problem........you could have a bad radio, bad channel on the radio or a bad receiver. Change the channel on the radio and then do the same on the receiver (make sure you match them together) and try it then.