FIELD TEST

The Minelab Sterling Metal Detector
By Andy Sabisch
From Page 6
April, 1994 issue of Lost Treasure

Minelab Electronics, an Australian-based company, was founded in 1985 with the goal of producing metal detectors at the cut­ting edge of technology. Features developed by their engineers which include fully-automatic ground bal­ancing, selectable operating frequen­cies, and Broad Band Spectrum (BBS) circuitry show that they have kept this goal in mind. Over the last two years, Minelab s engineering staff has been developing an afford­able metal detector specifically de­signed for coin hunters. The end re­sult of their efforts is the new Ster­ling which is intended to compli­ment the other detectors in the Minelab lineup.

FEATURES:

The Sterling is a VLF motion dis­criminator which operates at a fre­quency of 5 Khz. In addition to a full-range discriminate circuit, it features a non-motion All-Metal circuit for use in pinpointing targets. Unlike the other detectors manufactured by Minelab which feature either manual or fully-automatic ground balance circuitry, the Sterlings ground bal­ance has been preset at the factory at a level designed to handle most ground conditions.

Weighing just less than 3 pounds, it is one of the lightest metal detectors currently on the market. Its lightweight and balance provide for a metal detector that will remain com­fortable to use even after extended periods of searching. The Sterling comes equipped with an elliptical 8-inch by 6-inch concentric searchcoil featuring an open-center design which makes pinpointing targets quite easy.

The Sterlings S-shaped rod breaks down into three sections rather then two as on most other detectors and, as a result, can be packed into a small suitcase or even a briefcase. With more and more treasure hunters tak­ing metal detectors along when they travel, this feature makes the Ster­ling ideally suited for this applica­tion.

The most striking feature about the Sterling is the unique shape of its blue control housing. Oval in shape, it measures a diminutive 3-1/4 inches wide, 2 inches high, and 5-1/2 inches in length. Two knobs and two toggle switches mounted on the face plate control the Sterlings operation. The knob in the lower right corner serves a dual function. Labeled SENS, it turns the unit on and adjusts the detection depth or sensitivity of the Sterling. The knob adjacent to the SENS control labeled DISCRIMI­NATE selects how much trash will be rejected while searching. Even with the control turned to its maxi­mum (clockwise) position, all U. S. coins (with the exception of nickels) as well as large screw caps will still be detected.

Above the two knobs are a pair of toggle switches. The one on the left switches the Sterling between the motion discriminate and all-metal non-motion modes. By placing the toggle in the UP position, the detec­tor will respond to all targets, both ferrous and non-ferrous, and allow the operator to accurately pinpoint a target which may have been detected in the discriminate mode. The switch to the right of the mode select toggle is labeled RESET. This is used to retune the Sterling when searching in the all-metal non motion mode or to help in pinpointing a large target near the surface. It is spring loaded so that it will return to the normal position once it is released.

There is a 1/4-inch jack located on the front face plate which accepts any standard set of headphones. The use of headphones is recommended for two reasons. First, they help ensure that a faint signal from a deeply bur­ied (and possibly valuable) target is not missed due to background noise and second, it will extend the life of the batteries as headphones draw less power than the built-in speaker. Due to the location of the headphone jack in relation to the hand grip, a 90-degree plug is highly recommended to keep the plug away from the operators hand. If your current head­phones do not have this type of plug, a replacement can be purchased at your local Radio Shack store.

The Sterling is powered by eight (8) AA penlight batteries. They are contained in two plastic holders which are replaced by removing a panel on the rear of the control housing. While regular carbon batteries can be used, the factory recommends alkaline bat­teries for longer life and optimum performance. Approximately 40 hours of operation will be obtained from a set of alkaline. The LOW BATTERY ALERT feature warns the operator when they need replac­ing by producing a short high-pitched beep every 30 seconds. Nicad re­chargeable batteries can be used; how­ever, they are currently not available from the factory.

INITIAL IMPRESSIONS:

Being on temporary assignment and living in an apartment in northern Maryland, I decided to have Minelab send the detector to a friends house in New Jersey. To show how simple the Sterling is to assemble, my friends 13-year-old son, Joseph Harrick (who is not a treasure hunter himself), had the detector unpacked, assembled, and ready to operate in less than five minutes after opening the box with­out even looking at the manual.

Arriving at Jims house a few days later, we conducted an air test to see how the Sterling responded to vari­ous targets including coins, jewelry, small relics, and trash items. Setting the disc at 0 and the sensitivity at 8, all of the targets produced clear sig­nals out to a distance of 7 inches. Increasing the discriminate control to 6, the small wad of tin foil and nail began to produce choppy or broken signals that were readily distinguish­able from the crisp response from the other targets. With the control set at 7.5, nickels and most gold jewelry were rejected.

Winged pull-tabs were rejected at a setting just slightly above this point, and the rectangular-type tabs disappeared at a discriminate setting of 8.5. With the control turned fully clockwise, only the coins, a mans silver ring, a wine bottle cap, and a large wad of tinfoil were de­tected. While most of the trash was rejected, a noticeable loss of detec­tion depth was also evident which is typical of most detectors. As a rule, treasure hunters should only use that amount of discrimination needed to reject the most common type of trash target present in the area. Remember, if you are not digging ANY trash, you are probably missing valuable targets that someone searching behind you will recover!

Trying the Sterling in Jims test garden produced similar results. One feature that became immediately ap­parent was that pinpointing with the elliptical coil was both simple and accurate. On most of the test targets we did not even need to switch to the ALL-METAL mode. The Sterlings sweep speed was so slow that pin­pointing in the motion discriminate mode was possible. Several of the deeper targets would only produce an occasional signal; however, the shallow targets all responded clearly.

FIELD TEST:

Returning to my apartment, I took the Sterling to a well-used play­ground in a park situated on the Chesapeake Bay. Since the play­ground was covered with sand, tar­get recovery would be quite easy. Setting the SENSITIVITY control at 5 and the DISCRIMINATE level at 6, I began searching beneath the swings.

Almost immediately I received a solid signal, and reaching into the loose sand, recovered a recently-lost dime. Less than two feet away I found three dimes and a nickel bur­ied almost two inches down in the packed sand appeared to have been there for some time. Appar­ently other treasure hunters before me had missed these targets. Cover­ing the entire playground in about 30 minutes I walked over to a nearby bench to see what I had found. In addition to $1.27 in clad coins, I had three keys, a dime-store adjustable ring, and a pair of Matchbox cars that my 4-year old son Paul has already added to his growing collection.

Since I had kept the discrimina­tion level low enough to allow the Sterling to respond to small gold jewelry, I had also recovered a con­siderable amount of tinfoil from chewing gum, cigarette packs and potato chip bags littered the playground. As mentioned previ­ously, unless the trash becomes over­whelming, it is best to recover all of the targets in order to avoid missing that diamond ring or gold necklace.

One aspect of the Sterlings coil design that became noticeable while hunting this site was that it was quite sensitive to metal off to the side in addition to the top and bottom of the coil. As a result, I could not get any closer than 6-to-8 inches to the metal supports of the playground equip­ment without receiving a signal. While I did not try it, one of the optional double-D coils should work better under these conditions.

Another site I took the Sterling to was an elementary school built in the early 1950s which had given up a number a wheat cents and a few pieces of silver on my previous trips there. Setting the DISCRIMINATE control at 7 which would still allow me to detect nickels, and SENSITIV­ITY at 6, I walked out onto the old ball field. Based on past experience I knew that signals were few and far between so I wasnt bothered by the fact that I hadnt received a good signal ten minutes into the hunt. Sev­eral targets had produced broken sig­nals; however, based on the air test­ing and results from the playground, I simply passed them up realizing that they were probably larger pieces of iron or non-ferrous trash that the Ster­ling was trying to reject.

Nearing the sideline, I received a solid signal. Switching to the ALL-METAL mode, I quickly pinpointed the target. Cutting a small plug I reached in and removed a flattened screw cap resting in the bottom of the hole. The Sterlings accuracy in pin­pointing was quite impressive. The next several signals all turned out to be pull tabs, so I increased the DIS­CRIMINATE control to 9 (maxi­mum) and continued searching the grassy area between the baseline and the woods.

I spent almost two hours hunting this site, but as the sun began to set and the mosquitoes came out for a late supper, I decided it was probably time to head for home. Back at the apartment I dumped out my finds and sorted them out. I did have 9 clad coins, two keys, and a referees whistle which had come from depths ranging from just under the surface to 4 inches deep. Since the Sterling will still re­spond to screw caps even with DIS­CRIMINATE set at max., I also had over two handfuls of dirt-encrusted caps as well as several large wads of tin foil in my pouch.

Wanting to see how well the Ster­ling worked as a beach-hunting de­tector, I took it to a site on the Chesa­peake Bay which, while not truly a salt water beach, did contain brackish or slightly salty water. Considering this particular beach is detailed in the book Treasure on the Chesapeake, I knew I wouldnt be the first one to search it but hoped that the recent high waves and tidal action might have uncovered a few of the remain­ing goodies for me to find.

The actual beach was almost a 1/2-mile walk from the end of a dirt road, and it was hard to imagine this de­serted stretch of sand was once a popular destination for hundreds of people on warm summer weekends.

Looking around I could see the re­mains of the bathhouse and a picnic pavilion overgrown with vines and the frame of the original lifeguard chair was laying on its side sticking up out of the sand. Walking along the edge of the water I saw a cut almost 18 inches deep and about 30 feet in length which had been caused by the waves. Setting the SENSITIVITY to 8 and DISCRIMINATE to 6 I proceeded to search the eroded area. With the SENSITIVITY set at 8 the Sterling began to chatter, so I turned the control counter-clockwise until it quieted-down. At a setting of 2 1 was able to continue searching with only an occasional pop or chirp. While this did result in a loss of detection depth, hunting at higher sensitivity settings would have been impossible due to the false signals caused by the brackish water.

While the first few signals I re­ceived were not as crisp as those I had come to expect from coins, I was curious to see what the Sterling had located. After pinpointing the sig­nals, I recovered several large rusted bolts from depths ranging from 2 to 4 inches. Not wanting to lose any jew­elry that might be present, I left the DISCRIMINATE control at 6 and simply passed up any signal that sounded broken or washed-out.

Nearly completing my first pass across the cut. I finally received a solid signal. Removing a scoop full of sand, I rechecked the area. The Sterling indicated that the target was out of the hole so I began shaking the damp sand from the hand-scoop. Hearing something rattling around in the scoop, I reached in and removed a small black disc. Carefully rubbing some of the oxidation from the sur­face of the object, I could see that it was a Mercury dime dated 1941. Hoping that the cut held other coins from when the beach was in opera­tion, I continued searching the entire area.

After nearly two hours of hunting, I stopped and emptied my pouch. Besides the Mercury dime, I had re­covered three wheat cents, a beach tag, as well as a number of items such as fishing sinkers, lures, copper flash­ing, large brass fittings, and even a handful of pull-tabs. The targets had been buried at depths up to 5 inches and all had produced clear signals through the headphones. I found that headphones were required when searching near the surf as the signals from the deeper targets could not be heard through the built-in speaker over the background noise.

SUMMARY:

Minelab developed the Sterling in response to the requests of treasure hunters who wanted a simple-to-operate, reasonably priced metal detector. Features such as its rapid target response, all-metal pinpoint mode, and light weight show that the design team had people such as younger treasure hunters, beginners, competition hunters, or people look­ing for a back-up unit in mind during the Sterlings development phase.

Highly mineralized ground and wet salt-water beaches will produce vary­ing amounts of chattering and falsing; however, by reducing the sensitivity and raising the coil off the ground, this can be minimized to some extent. Using the Sterling in high-trash areas requires both practice and patience since with the discriminate control set to MAX, screw caps and other large trash objects will still be detected.

The Sterling sells for $399 and is covered by a two-year parts and labor warranty (one-year on the search coil). The warranty applies only to the origi­nal owner and is not transferable. Optional search coils include a 6-inch round, 8-inch round, and 12-inch el­liptical all of which utilize the double-D design. The coils sell for $120 apiece and coil covers are avail­able.

For the name of your nearest dealer or information on the complete line of Minelabs Australian-made metal detectors, contact the importer at (702) 565-1353 or write to Down Under Treasures, P. 0. Box 92080, Henderson, NV and be sure to men­tion you read about their newest de­tector in Lost Treasure.



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