Get the hours on any machine, and you will find stuff. its about getting the coil over the objects.
you get out of this hobby, what you put in.
I say this to all new detectorist.
A. do some bench testing (turn on the machine away from any metal) then take different coins, metals, and run the object by the coil to see how your machine reacts
B. make a test garden. put different object at different depths in the ground. spread them out far enough apart. also put object like pull tabs, bottle caps, etc.
C. detect your yard, family's yard, your friends, and neighbors properties. to really know a machine you should have 50-100 hours on the machine.
D. Watch Utube video's about your machine, ask others on the board who have the same machine.
next do some research and venture out to your local town. parks, schools, public areas. (make sure to check your local laws and regulations).
Good Luck and have fun. Remember detecting is about the adventure, getting out with your son, doing something outside is better then sitting watching TV.
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Here are the entry level machines I usually suggest people to buy.
TESORO COMPADRE is 160$
(not in that specific order. )
Garrett Ace 250/350, Fisher F2, Tesoro, new style Whites coinmaster,).