Joe is the third and final character in Mr Prepper, who assigns tasks to the main character. You'll find him in the junkyard, but only after 5pm. He's unlocked by completing the Bob's Jacket task.
Mind Control Protection
Joe's first task is Mind Control Protection. Go visit Joe and talk to him at the junkyard in the afternoon.
When you find Bob's jacket, he'll point you to the Junkyard where you'll find Joe. Joe is only available after 5pm. Talk to him and tell him about the broken revolver. After the conversation, you will unlock the task and the option to trade in the Junkyard.
Joe will ask you to bring him some aluminum foil. You'll find it during your first trip to the desert. It will be lying somewhere on the ground, looking similar to a white sheet of paper or a piece of cloth. Bring the foil to Joe and come back the next day for a new task.
The Missing Cryptid
After completing the Mind Control Protection task, Joe will complain that his dog, Chupacabra, has disappeared. You need to go into the woods to search for it.
You will find the dog at level 4 of the forest, to which you should have access by now. Reach the final, seventh secondary level of the location.
Near the grotto, you will find a cage. Open it to free the dog and then go back to Joe. He will have another task for you (the cage is located near the plane crash site from Jenny's Air Crash Investigation mission).
As a reward for the mission, Joe will give you the access card to level -4 of the mine. It's required to continue the main story.
Radio Free North America
The Radio Free North America task is initiated by completing The Missing Cryptid mission.
Bring electronics x5 to Joe. If you have them on you, you can give them to him right away. Either way, you have to come back the next day (note: although the game allows you to start on the same day, you won't have enough time to actually complete the task).
You must now catch the radio broadcast signal. To do this, you need to go to the desert (it's a good idea to bring lots of fuel) and at each stop, use the antenna attached to the mask. It's worth testing it at Joe's. To catch a clear signal, you have to make 5 trips through the desert. Therefore, it's necessary to bring enough fuel and to begin your journey in the early hours of the morning. By completing this mission, you will earn Joe's trust and he will help you find Fort Observer.