When coin hunting with the TDI we all know using the GEB around 1.5 will drown out anything that isn't silver or copper but with a good loss of depth.
If you take the GEB and crank it up to about 3.75 or 4 in High conductivity PD=10us you might get some small nails that will fool you but if Iron is masking a target like a silver dime from other detectors you will find it with the GEB at 4 or just under. Also Brass will come in alittle bit so you can dig some relics. When in HIGH mode you wont ever hear low conductors such as nickle, small gold (coins below $5). If you come across a signal and it sounds good one way step 90 degrees
and try it from a different direction and if it repeats with the same sound its about 90% chance that its silver or copper coin. If it jumps or is longer or shorter
it is most likely wire, trash, or silver chain and so on.

For nickles and small gold coins you need to use low conductive which most people when coin hunting don't like to do since more trash can fool you in the Low setting.
If you set the GEB at or around 8 or 9 PD= around 10us with the conductivity in low you won't pick up most iron so you can first hunt for those silver coins and then for the nickles and gold coins in this low setting. You'll also pick up some small tacks or wire sometimes but most of the signals of trash are very jumpy or don't repeat with a smooth tone.

If you follow these settings you are sure to find things where most VLF's wont find them. As a reminder this is just for coin hunting and not for relics which I use different settings and dig more iron.

Also the biggest thing with the TDI is to move with a slow swing speed and your sure to get anything with in detector range. Another thing is if your using the 12in DF coil the inner coil is what you want to focus on when gridding. Make sure your overlapping your swing about 50% of the coils diameter.