well since you are kind of new to the mxt I would take and learn how the mxt response to coins and then learn the numbers on the vdi. If you take your time to look I started a post of the whites forum for mxt vdi numbers, that may help you out a little if you learn the numbers. I learned the machine in coin mode first, then I switched to relic mode as I like to hear all of the resposes the machine is telling me especially the 2 tones. This is how I set up my mxt when I go detecting;
I ground balance it then I set the switch to auto track
I turn the gain up as far as it will go without it giving me false signals(Where I live it is about +2 generally)
I search in relic mode and I turn the discriminator knob to where it is between 3-1/2 to 4
I like to hear the tones it is giving me with the high and lower one
If it is giving a mixed signal and it stays on the positive side more than the negative side of the scale I am going to dig especially if it is 6 inches deep or more. The mxt is pretty good at ID'ing something 6 inches or less. I would not recommend searching in prospecting mode because it turns into a totally different machine. It will pick up everything that is in the ground that is iron and highly minerealized, even tree roots, so it will be a nightmare trying to determine whether to dig or not in prospecting mode. Maybe this will help you out a little. There is alot more about the MXT on the regular whites forum if you take the time to look. Tim