Having been a metal detector hobbyist some years before the advent of discriminators, I was delighted with their introduction in the 70’s. I thought I had arrived when I got my first discriminator, a Coinmaster from White. I set the discrimination on that detector as high as I could because I was tired of digging for aluminum caps, tabs, and screw caps that abounded in central Florida schoolyards and beaches. Initially, the results were exciting! I was finding more treats and a lot less junk. Unfortunately, I didn’t realize all that I was missing until my nickel count and gold find totals were completely gone. So I became a student of discrimination and still am today. I would like to share with you some of my insights from many years of using discrimination.

In a recent article I suggested using the all metal mode or zero discrimination as a means of finding more good targets and avoiding much of the target masking that occurs with all conventional VLF detectors. Here you listen to all the targets, learning to discern a good or semi-good tone from all the target tones. This is a time consuming process, but using a good test garden can enhance learning this skill. In many poor quality environments, this is the best possible method of discrimination.

Lowering your detector’s sensitivity level is the only way I know of to increase good target finds in areas with a lot of trash, as well as finding some targets that are masked by rejected targets. The amount of depth loss you get depends on the detector. My favorite detectors to reduce sensitivity and still get good depth are the Fisher brand.

The Fisher 1200 series of detectors with dual discrimination controls also adds another trick to discrimination. When a target is accepted at the lowest discrimination level, indicated by a soft “buzz” signal, but changes to a “click” or “pop” when forward is pressed to activate Discrimination 2, the broken signal alerts the operator about the possibility that a nickel, gold coin or ring has been located. But if the same soft signal repeats when Discriminate 2 is activated, then the chance that the target is a penny, plated, or silver is good. This identification process can be accomplished in seconds and applies to all metal detectors with two separate discrimination controls.

My favorite discrimination technique is what is called “reverse discrimination.” This technique can be used with all analog VLF/TR detectors. Search in VLF all-metal mode and when a target is discovered, place it in the exact center and place the coil on the ground at that exact point. Without moving the coil, change the mode to TR and lift the coil off the ground. If the audio stays the same or drops off, you’ve got a good target. If the signal increases in volume when the coil is raised, the aim is bad. This explains the reverse designation of this technique, since in analog detectors, good targets will produce volume and bad targets are quiet.

One key to improving your discrimination with metal detectors that have ground balance controls that work in both all metal and discrimination modes, is to make sure to ground balance your detector before adjusting its discrimination. The reason for this is that the phase shift takes place at the ground roll and switching to discrimination after the ground roll will prevent any possible phase shift in your discriminator.

Reduce your discrimination in almost every treasure hunting environment and yes, reduce your sensitivity level at the same time. Turning it down a bit will increase its depth in almost all areas of the site. Here’s to “dig it”! larry