Having been a metal detector hobbyist some years before the advent of discriminators, I was thrilled with their introduction in the 70’s. I thought I had arrived when I got my first discriminator, a White’s Coinmaster. I sat that detector’s discrimination as high as I could go because I was tired of digging pop tops, pull tabs, and aluminum screw caps which abounded in the school yards and beaches of central Florida. Initially, the results were exciting! I was finding more goodies and far less junk. Unfortunately, I did not realize all that I was missing until my nickel count and gold find totals disappeared completely. I then became a student of discrimination and still am today. I would like to share with you some of my knowledge 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 bypassing so much of the masking of targets that takes place with all conventional VLF detectors. Here you listen to all 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 trashy environments this is the best possible method of discrimination.
Lowering the sensitivity level on your detector is the only way that I know to increase good target finds in high trash areas as well as finding some targets that are masked by rejected targets. How much depth loss you get depends on the detector. My favorite detectors for lowering sensitivity and still getting good depth are the Fisher brand.
The Fisher 1200 Series of detectors with dual discrimination controls also adds another trick to discriminating. When a target is accepted at the lower discriminate level-indicated by a smooth “buzzing” signal-but changes to a “snap” or “pop” when pressed forward to activate Discriminate 2, the broken signal alerts the operator to the possibility that a nickel, gold coin or ring has been located. But if the same smooth signal is repeated when Discriminate 2 is activated, then the possibility of the target being a penny, clad or silver coin is good. This identifying process can be accomplished in seconds and applies to all metal detectors with two separate discrimation controls.
My favorite discriminating technique is what is termed as “reverse discrimination”. This technique can be used with all analogue VLF/TR detectors. Hunt in the VLF all-metal mode and when a target is discovered, pinpoint it to the exact center and place the coil on the soil at that exact point. Without moving the coil, switch the mode to TR and lift the coil from the the soil. If the audio remains the same or decreases you have a good target. If the signal increases in volume when the coil is lifted the target is bad. This explains the reverse designation for this technique, as in analog detectors, good targets will produce volume and bad targets are silent.
A key to enhancing your discrimination with metal detectors that have ground balance controls that are functional in both all metal and discrimination modes, is to make sure you ground balance your detector before adjusting your discrimination. The reason for this is that phase shift takes place in ground balancing and switching into discrimination after ground balancing will avoid any possible phase shift in your discriminator.
Lower your discrimination in almost all treasure hunting environments and yes lower your sensitivity level at the same time. Lower it a little will increase your depth in almost all site areas. Here’s to “diggin it”! Larry