Tom's suggested settings.

It stopped raining and snowing and the sun came out.I went to a real small town to hunt an old school yard and fairgrounds.I found lots of coins nothing old though and 3 pieces of kids silver jewelry.
I used the F 75 with the sensitivity on 70,disc 6,4 tones.Fast grabbed and went hunting.The school, yard was chattery with this setting.I could live with it but lots of snap,crackle and pops.The electric lines came in the school on the other side of the building.Tons of zincs,a few quarters and a bunch of dimes.I was within a year of the coins being old enough to be silver.Same settings at the fairgrounds.The detector ran whisper quiet.The only sound was a good target(except for some foil I dug) .The ground,gumbo clay,was super saturated with water at the fairgrounds.The school yard ground was real dry.Would that be the reason for the difference in how smooth the detector ran?The school yard was trashy though.The fairgrounds were surprisingly clean.

Kick, when it was chattery ry sens 60 and disc 10

If the coil is held still in free air..... and the detector is chattering....,,,,, it's electromagnetic interference.
If you are sweeping the coil.... and it's quite 'chattery',,,,,, then it is ground targets.....,,,,,,,, the worst being many tiny/microflakes of iron. This is most common around very old buildings that had steel/tin roofs.

Thanks Tom and EZ.I'm still sore from yesterday.

You have to put up with a little chatter,as long as you are quite with the 75 in the air.The chatter meanes nothing,You will be able to hear the goodies.

With only a little chatter in the air....... when you sweep the coil, the chatter usually subsides.