On this Mr Prepper guide page, you will learn how to Earn Joe's trust while doing missions for Joe from the Junkyard.
Earn Joe's trust is the goal of one of Joe's missions in Mr Prepper. In order to gain his trust, complete all his missions. In the last mission, Radio Free North America, your goal is to intercept the signal.
To do this, go to the desert, go through its 5 stages (you need 20 units of fuel for this), and then intercept the signal. To be sure, check the antenna on each stage. Then go back to Joe and give him report. That way, you complete this mission and move on to the next one.