FIELD TEST

Minelab Electronics Gt 16000 Ground Tracker
By Andy Sabisch
From Page 15
November, 1990 issue of Lost Treasure

Minelab Electronics, located in Norwood, Australia, currently produces nearly 80 percent of the metal detectors being used in that country. Their line of metal detection equipment has been adopted by both recreational treasure hunters as well as governmental and industrial organizations throughout Australia. The GT 16000 Ground Tracker is the top of the Minelab line which presently consists of two other models: the Eureka Ace Dual and the Eldorado Mark II.

The first time I saw the GT 16000 was at the GPAA Gold Show held in Atlanta earlier this year. The importers for Minelab, Bob and Wilma Beaumount from Down Under Treasures, were demonstrating its performance with the help of veteran prospector Hoss Blackman. The GT 16000 impressed nearly everyone who saw its ease of operation and overall sensitivity.

FEATURES

The GT 16000 Ground Tracker is a true automatic ground-canceling detector with both a motion discriminate and non-motion all-metal pin-point mode. It also features a unique variable discriminate control for rejecting unwanted targets with no loss in sensitivity.

The most important feature of the GT 16000 is its ground-balance circuitry. Most automatic ground-balance detectors presently on the market do not actually adjust for the mineralization present in the ground, but rather use a preset ground-balance setting that is expected to be sufficient for most areas to be searched.

In areas of high mineralization or where the mineralization changes rapidly in a short distance, the sensitivity must be decreased on these types of detectors in order to avoid falsing or chattering resulting in reduced depth and the potential for missing valuable targets.

The GT 16000s circuitry actually senses the mineralization present in the soil and compensates for it to provide maximum sensitivity in all ground conditions. Also, once the ground balance has been set by the GT 16000, it will automatically maintain the optimum setting, even if ground conditions change, with no loss of sensitivity.

The GT 16000 is mounted on a modified S-shaped rod, and at 3 1/2-pounds with the standard eight-inch Double D searchcoil, is both extremely lightweight and well balanced. The armrest is held on with a spring clip and is adjustable to allow users to compensate for different arm lengths. It also incorporates a built in detector stand which keeps the detector upright when recovering a target.

The control housing, made of high-impact Lexan, snaps onto the shaft and mounts in any of three positions to allow the user to adjust for hand and finger sizes. The GT 16000 comes with an extension cable and a nylon bag to allow the control housing to be either hip-mounted or hung over the shoulder. This feature is quite useful when searching in shallow water to avoid damaging the detectors electronics, or when using the optional 11-inch search-coil for an extended period of time.

Since the GT 16000 is made in Australia, the names of some of the controls are different than those on detectors usually seen in the United States. The THRESHOLD control knob is used to set the audio thresh-old heard through either the built-in speaker or a set of headphones. The SENSITIVITY control is used to set the depth of detection the GT 16000 will utilize when searching.

The VOLUME control turns the detector on and adjusts the volume of the signal produced when a target is detected. The knob located above the THRESHOLD control is labeled DISC and, when set in the fully counterclockwise position, the GT 16000 functions as an all-metal detector. As the control is turned clockwise, the level of discrimination will increase.

Another unique feature is that the use of discrimination does not reduce sensitivity or detection depth as seen on other detectors. All targets will still produce an audible response; however, those targets that fall below the discriminate setting (reject) will have a staccato or chatter sound, while good targets will produce a clear signal. This eliminates the problem of a good target being masked by a trash target nearby and ensures that the user will leave very few, if any, good targets behind.

The three-position toggle switch labeled ENHANCE, NORMAL, and BOOST affects the audio output of the GT 16000. The normal setting is the one most frequently used and produces a normal signal as the loop passes over a target. The BOOST setting activates a built-in signal booster which amplifies weaker signals and provides for even greater depth than in the normal mode.

The ENHANCE setting activates a circuit that further aids in the identification of a good target, especially when searching in the area of hot rocks, and produces a fluttering tone when the target is worth investigating.

The toggle switch which is labeled SOIL-NORMAL/DIFFICULT is used to compensate for highly-mineralized ground. If the mineralization changes rapidly or you are searching in the surf at a saltwater beach, operating in the DIFFICULT position will result in smoother operation with very little effect on overall sensitivity.

Above the SOIL switch are two toggle switches which select the operating mode and control the ground-balance circuitry. The RESET switch is used to initially set the ground balance of the GT 16000 and will be described in detail later.

The other switch selects which operating mode will be used. The lower setting places the GT 16000 into a motion discriminate mode which will automatically track and adjust for any changes in ground mineralization. The other two positions select either a motion discriminate or non-motion mode with the ground-balance setting being fixed.

Another feature of the GT 16000 is the high-pitched broken audio response that is produced if the searchcoil is passed over a target that is either very large or extremely close, and the detector is unable to identify it. If this occurs, the searchcoil should be raised an inch or two above the ground and the area re-swept to accurately identify the target.

The GT 16000 is powered by 8 AA penlight batteries which are located in a compartment on the bottom of the control housing and are separated from the electronics to avoid damage in the event the batteries leak. Alkaline batteries will provide between 40 and 50 hours of use, and rechargeable batteries can be used with no loss of performance.

FIELD TEST

The GT 16000 comes with a detailed instruction manual, a pocket-sized field reference card, and a VHS video tape that provides all the information needed to quickly master its operation. After reading the manual and viewing the video, I spent some time in my test garden familiarizing myself with the GTI6000s response to various targets. The depth at which targets could be detected was truly amazing, and I was able to detect a freshly buried penny at nine inches in the highly mineralized clay so common to this area.

A few days after I received the GT 16000,1 took it to New Jersey to try several sites that had been heavily hunted over the years. The first site was a small beach that had been in use since the 1940s and, while it has been hunted for years, still contains a number of good targets deeply buried in the sand.

In order to reject only the small ferrous targets such as bobby pins, I set the DISC control to two, and turned the SENSITIVITY control to the three oclock position, the sound switch to NORMAL, the mode switch to MOTION GB TRACK, and the soil switch to NORMAL.

Ground balancing the GT 16000 is extremely easy and took less than 30 seconds to accomplish. This is done by turning the unit on and adjusting the THRESHOLD knob until a slight tone is heard. Next, raise the searchcoil approximately 12 inches above the ground and hold the RESET toggle in the up position.

While holding the switch up, raise and lower the searchcoil to the ground until the threshold remains constant. When the toggle is released, the GT 16000 is correctly ground balanced and, in the MOTION GB TRACK mode, will remain so despite changing ground mineralization. This is called Fast Ground Balancing and is the recommended method of setting the initial ground balance.

The GT 16000 will balance itself without performing this procedure as the searchcoil is swept over the ground in approximately 60 seconds and this method may be preferable to some users. In either case, the GT 16000 will maintain the optimum ground-balance setting to achieve the maximum sensitivity possible.

The first few signals produced coins that had been recently lost and all were within three or four inches of the surface. Upon receiving a faint signal near the waters edge, I placed the sound toggle to BOOST and the increase in signal strength was truly amazing. Carefully recovering the target to see how deep it was, I found a 1965 clad quarter at nearly 12 inches.

Over the next 30 minutes I recovered several coins and 2 rings at depths ranging from 6 to 14 inches. I decided to hunt the shallow water; however, since I had forgotten to bring the extension cable, I was limited to searching in water knee-deep or less. Among the better finds made in the water were two Mercury dimes from the l930s that were found deeper than any of the coins I have found previously at this site.

The next site my treasure-hunting partner, Jim Harrick, and I went to was Fort Mott State Park. This area, situated on the Delaware River, was originally constructed during the Civil War and saw active service until the 1920s. The parade grounds have produced coins and military artifacts in large numbers in the past; however, Jim had said that very little was being found anymore.

Due to the large amount of ferrous targets from the old barracks, I set the DISC control to four which would produce the staccato sound on smaller ferrous items such as nails.

I began searching near the old flagpole, and almost immediately received a clear signal. I called Jim over to check the signal with the top-of-the-line detector he was using, but he was unable to get a response even in ALL-METAL. Cutting a plug and rechecking the hole indicated that the target was still deeper. At nearly seven inches I found a fired percussion cap (slightly larger than a .22 bullet), my first at this site.

Over the next two hours, I recovered a number of targets including 45-70 shell casings, boot tacks, an eagle cuff button, an 1887 V nickel, an 1899 Indian head penny, and a few modem coins. Most of these targets were undetectable by the other detector we had with us.

One point to mention is that the GT 16000 was unable to audibly reject extremely deep iron objects. Nails and bolts that were deeper than eight or nine inches produced a good response until the plug was removed and the coil could be brought closer to the target. While this did mean some extra digging, the GT 16000 was able to locate good targets at impressive depths.

Returning to Georgia, I took the GT 16000 to an area near Kennesaw Mountain to search for Civil War relics. This site is known for its highly mineralized ground, and the area that had sustained the heaviest fighting was directly beneath high-tension electrical towers. Despite the 95-degree temperatures and bone-dry ground conditions, I was hoping to recover at least something from the battle that took place here 125 years earlier.

Despite the mineralization present, I didnt need to use the DIFFICULT setting on the soil toggle switch as the GT16000 operated quite smoothly, even with the sensitivity at two oclock. The soil in Australia must be highly mineralized if the DIFFICULT setting is needed for everyday treasure hunting there. The first few signals produced .22-caliber bullets and shell casings at depths of up to 5 inches, the GT16000 was definitely quite sensitive.

Nearing the west face of the hill, I received a solid signal that was fairly faint in the NORMAL mode and produced the fluttering sound when checked in the ENHANCE setting. At four inches I hit a hard layer of clay that required me to use both hands with my mattock to dig into it. After several minutes, I recovered an unfired Confederate minnie ball at nearly 10 inches.

I continued to search the area and, despite the changing mineralization, hot rocks, dry ground, and high tension wires, was able to recover several more minnie balls and lead fragments at depths ranging from 5 to 10 inches. I sent the GT 16000 to Jim Harrick to try it on some of the black sand beaches along the New Jersey coast. Jim hunts the beaches from Wildwood to Cape May quite regularly, and has used a number of detectors in his searches.

The first site that Jim took the GT 16000 to was a lake near his house that had been drained several months previously and had been searched by a number of treasure hunters, including a group hunt by one of the local clubs. Arriving at the site, Jim immediately noticed filled-in holes all over the beach area so he was not expecting many good finds.

Setting the Disc control to four in order to reject bobby pins and barrettes, the SENSITIVITY to three oclock, and the SOUND switch to BOOST, he easily ground-balanced the detector and began to hunt. Less than five minutes after he started, he received a clear repeatable signal and carefully began to recover it. At a measured 14 inches, he recovered a 1946 Roosevelt dime.

While this depth on a coin the size of a dime is almost unbelievable, the sensitivity of the GT 16000 combined with the damp sand and the halo effect from the length of time it had been buried made it possible. Jim spent another hour at this site and found several targets that had been missed by other hunters either due to small target size or extreme depth at which they were located.

Jim spent several hours searching the beach at Cape May and, while the only targets he recovered were modem coins, the detector had worked flawlessly. He said that he had no problem working from the dry sand down to the set sand and into the surf, and that the automatic ground-balance circuitry had compensated for the changing conditions extremely well. Jims overall comment on the GT 16000s performance was This is the best beach machine I have ever used, bar none!

I used the GT 16000 at several other sites around Atlanta, and was able to recover a number of valuable targets from areas that others had given up on due to the high mineralization and sparse finds.

SUMMARY

While the GT 16000 Ground Tracker was designed to locate extremely small gold nuggets deeply buried in highly mineralized ground, it proved itself to be an extremely effective detector for relic hunting, beach hunting, and coin hunting as well. Its automatic ground-balancing circuitry is truly unique, and allows even a novice to search under even the most adverse ground conditions with the success of a professional.

The discriminate circuitry does result in some extra digging due to the fact that the GT 16000 does not discriminate as deeply as it will detect a target however, based on the depth at which good targets were located, the extra effort is definitely rewarded. In many of the sites where the GT 16000 was tested, good items were located at depths where other detectors were unable to indicate that a target was even present.

While the GT 16000 Ground Tracker is not a metal detector for the weekend coin hunter, it will provide what a treasure hunter needs who is looking for a detector that incorporates the latest technology with the depth, sensitivity, and ease of operation needed to spend more time finding treasure and less time making adjustments to the detector.

If you are a serious treasure hunter and are looking for a new metal detector that will find targets in heavily hunted areas, you need to take a look at the GT 16000 before you buy.

For additional information on the entire line of Minelab metal detectors and accessories, and the name of your nearest authorized dealer, write the importer at Down Under Treasures, 13956 Timberwood Place, Port Orchard, WA 98366 or call them at (206)876-8153 and mention that you read about it in Lost Treasure.



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