Garrett Electronics Infinium Ls
By Andy Sabisch
From Page 26
August, 2003 issue of Lost Treasure
Garrett Electronics has been a leading metal detector manufacturer for nearly 40 years building detectors using virtually all of the proven circuits ranging from BFO's to TR's, VLF's and PI's. Garrett's experience with Pulse Induction-based detectors dates back more than 20 years and they have consistently been recognized as top-performers by treasure hunters world-wide.
Having used all of the pulse detectors produced by Garrett starting with the original XL-500 back in the early 1980's, I was anxious to see how the new Advanced Pulse Induction (API) circuitry in the Infinium performed in the field.
The Infinium LS was designed for use both on land & in the water and due to a pulse induction's (PI) ability to ignore even the most adverse ground conditions and detect targets at maximum depths, the Infinium is ideal for electronic prospecting, relic hunting, beach hunting & treasure diving.
The Infinium is waterproof down to 200', hence the LS (Land & Sea) designation. It can be mounted in one of 3 positions on the shaft or belt-mounted with the included pouch. Hip mounting will reduce the weight of the detector by almost 2 pounds and allows for easier operation of the controls to aid in identifying and pinpointing targets. For diving, shaft mounting is recommended to avoid becoming entangles in the cables.
The Infinium comes with a 10"x14" Double-D coil. The advantage of a Double-D coil is its ability to detect targets at maximum depth the entire length of the coil, down the center strip. This eliminates the need to overlap each sweep for complete coverage; however, pinpointing is a bit more challenging and a slight loss of sensitivity to very small targets is experienced when compared to using a concentric (mono) coil.
Only three knobs control the Infinium's operationthreshold, automatic ground track and discrimination. The threshold control serves two purposes. The first is self-explanatory as it sets the audio threshold and should be set so it is just barely audible through either the standard headphones or optional waterproof dive headphones. By turning the knob fully clockwise, you enter the frequency adjust mode. In this mode, in conjunction with the Discrimination knob, one can make 32 minor adjustments to the Infinium's operating frequency to eliminate interference from other detectors or outside electrical sources. The selected frequency will be retained when switching back to the threshold adjust circuit. The operator's manual covers this adjustment in detail.
The ground track knob turns the unit on and is used to select the mode of operation best suited for the existing ground conditions. The choices are slow, lock or fast. Initial ground adjustments are made in either the slow or fast settings; however, lock is the preferred mode of operation and provides maximum detection depth. If the detector becomes erratic due to changing ground mineralization, one of the other two modes should be used depending on how fast it changes; i.e., the slow setting for slight changes and the fast setting for rapid changes.
The discrimination control is one that may seem out of place on a PI detector. Garrett Electronics has successfully incorporated a discrimination circuit on their past PI machines, and their engineers have further improved this circuit on the Infinium LS. The manual recommends that the discrimination control be left at "0" for maximum detection depth; however, there are a few tricks one can use with this control not covered in the manual that further enhance the Infinium's in-field performance. These will be covered in the Field Test section below.
The Infinium LS is the only PI-type detector that features an audio target-ID circuit. The two-tone audio response varies depending on the type of target detected. A low conductive target such as gold jewelry, nickels, pull tabs, bullets and smaller gold nuggets will produce a high tone followed by a low tone as the coil passes over it. A high conductive target such as pennies, clad & silver coins, brass artifacts and large gold nuggets will produce a low tone followed by a high tone. Due to the way PI-detectors react to iron, a low-high tone will be received when iron is detected.
Eight AA batteries that provide about 15 hours of use power the Infinium. When the unit is first turned on, the battery strength is indicated though a number of beeps. Four beeps indicate they are fully charged while one beep means you have less than an hour of hunting time remaining. A rechargeable battery system is included with the Infinium that will save on battery costs; however, alkaline cells can be used if you cannot recharge them. Another example of Garrett's through design process is the fact that the battery pack is held in a compartment separate from the electronics so that if any water leaks into the battery area, it will not damage the detector.
Factory personnel said they wanted me to take the Infinium LS to the most challenging sites I could in terms of ground conditions for a through assessment of how it performed and sites that fit the bill abound in my home area. Northeast Pennsylvania is tough for metal detecting due to the adverse ground conditions found in many areas. Hot rocks and the use of coal as a heat source for more than 200 years has resulted in layers of mineralized cinders providing a challenge for even top-of-the-line detectors. After spending some time bench testing the detector and trying it in my test garden, I was ready to give it a workout.
The first site I selected was an area adjacent to a canal that paralleled the Susquehanna River for some 80 miles where several homes had stood in the mid-to-late 1800s. I'd heard of a few good finds having come out of this site over the years but between the thick layer of leaves that covered the area and pockets of coal cinders, any good targets were difficult at best to detect.
I opted for the belt-mount configuration so that I could adjust the discrimination control to see how the target response changed at different settings. Letting it compensate for the ground mineralization, I switched back to the lock mode and began hunting near one of the foundations. I came across more targets than I had expected, and since this was a field test, took the time to recover each one and see what had been detected. The first few signals turned out to be the ever-present shotgun shells at depths of up to eight inches. One had full metal case and dated back to the early 1900sa nice find. A low-high signal near the base of a large tree produced a silver-plated spoon with an 1874 patent date on it. Things were starting to look up!
The next signal resulted in nearly 10 minutes of frustration as I tried to find what the Infinium had detected. To my surprise, it turned out to be small, less than in diameter, lead round ball from the 1800s! I had not expected the large coil to be able to detect targets that small; however, holding the tiny target in my hand made me realize that Garrett's engineer's had packed a surprising amount of performance into the Infinium.
On subsequent signals that seemed small in size, I opted to increase the discrimination control to shrink the target response and aid in pinpointing the targets. Then, as I loosened up the dirt, I would pass handfuls across the top of the loop and listen for any response. Once I knew the target was in my hand, I simply dumped the dirt on a hand towel and spread it around until I saw the target. Over the next few hours I came up with additional round balls and even a percussion cap using this technique.
My results were more than satisfactory considering the site conditionsbullets, the spoon, an 1867 Indian Head, a well-worn seated dime, assorted shotgun shells and a few pieces yet to be identified.
After my experience at this site, I realized that I needed to spend more time learning the ins and outs of the Infinium in my test garden. The first aspect of its operation that I wanted to focus on was pinpointing targets. The time it took me to recover targets in an overgrown site like the one I had been to was a little frustrating; however, after discussions with the factory, I was determined to find a technique that would eliminate this frustration. Since a Double-D coil is equally sensitive down the center hot section, you cannot use the method most of us use with a concentric coil; i.e., criss-cross the target and when the signal is the strongest, the target is beneath the center of the coil. A trick I have used on Double-D coils before is to wrap a piece of brightly colored electrical tape around the front and back edge of the coil. After doing this, I spent over an hour in the test garden developing a set of techniques that seemed to make pinpointing much more precise and after several trips to actual sites, found that they worked fine in this applications as well. I have summarized them below:
Pinpointing on land or on the beach: Hunt with the discrimination set at zero. When you get a signal, swing back and forth to set an idea as to where the target is; i.e., somewhere under the hot strip in the center of the coil. Wiggle the coil from side to side no more than an inch or so. This will keep the detector from trying to produce the high-low or low-high signal with the resulting delay that may make it confusing as to where the signal actually is. Slowly pull the coil towards you while moving it side-to-side an inch or less until the signal fades and drops off entirely. Stop moving the coil. The target will be just in front of the coil in line with the colored tape on the coil tip.
Pinpointing in shallow water: Shallow water hunting presents additional challenges since you will normally not be able to see the coil on the bottom. This makes it hard to know where to dig and recover a target. Hunt with the discrimination set at zero. When you get a signal, swing back and forth to set an idea as to where the target is; i.e., somewhere under the hot strip in the center of the coil. Wiggle the coil from side to side no more than an inch or so. This will keep the detector from trying to produce the high-low or low-high signal with the resulting delay that may make it confusing as to where the signal actually is. Slowly push the coil away from you while moving it side-to-side an inch or less until the signal fades and drops off entirely. Stop moving the coil. The target will be just in back of the coil in line with the colored tape on the coil tip. If you cannot see the mark due to the clarity of the water, slide your foot along the bottom until you feel the coil and then place the scoop adjacent to your foot so that when you dig, you will be removing sand or mud from the area where the target is.
More Accurate Pinpointing: If you are in an area where you want to minimize the size of the hole you have to dig or need to be precise in locating the target, this technique will do two things 1) allow you to precisely pinpoint targets and 2) identify targets to some degree. When you get a signal, swing back and forth to set an idea as to where the target is. Move the coil away from the target and bring the DISC control to the mid position. This will result in a loss of detection depth but the signal will be sharper and more defined in terms of coming in closer to the center of the coil (where the decal is on the top of the coil). If this is adequate in terms of pinpointing the target, go ahead and dig it. You can also lift the coil off the ground to further shrink the target response if the object is close to the surface.
Identifying Targets: If you want to try to target ID the item, you will need to do some beach testing beforehand. Staring with the disc set at 0, pass targets similar to those you will be looking for (or wanting to reject) across the coil. Slowly increase the disc control and write down when the signal fades and when the signal disappears entirely. I found that nickels go way around ƍ' for example. Make a list of what goes away when and either memorize it or bring the list with you into the field. To use this technique effectively, the hipmount configuration will work the best as the discrimination control can be easily adjusted with the free hand. When you get a signal, increase the discrimination control to the first point on your list. If the signal is gone, you have probably identified what the item is. Continue to increase the disc control until you either loose the target or the control is fully clockwise. Note: A deep signal may drop out before you reach the setting on your list due to the loss of detection depth in the discriminate mode. The response you receive will be much easier to center the coil over resulting in smaller holes and faster target recovery.
Timing of field tests is usually a bit off and this one was no exception. The weather changed for the worse and we went through a spell with the high temperature being 30 degrees or less. This did not make for ideal water-hunting weather but such is the life of a field tester!
My wife & I took the Infinium and my dive gear to an old public swimming lake about 40 miles away to see what might turn up. I had hunted this site a few years ago and found the high concentration of hot rocks both on the beach and in the water to be quite bothersome. Switching to the underwater headphones, I ground balanced the Infinium, selected the lock mode, I began hunting the exposed beach and immediately started to pick up several targets. Since I was using a long-handled scoop, pinpointing was not of real concern so I opted for the "wiggle and pull back" technique. Several coins, including a 1952 wheat cent, and some of the pesky pull-tabs and screw caps turned up at depths ranging from just under the surface to eight-plus inches. Based on the fact that there were still good targets on the beach, I was hoping the deeper water would also hold some keepers. One thing I noticed was that the shaft flexed noticeably with it fully extended in shallow water; however, by shortening the shaft two notches, it stiffened up.
It was with much trepidation that I put on my wetsuit and carried my hookah to the water's edge. Wading out to where the bottom started to slope downwards, the icy water filtered into my suit and slowly started to warm up. Starting the motor on the hookah, I put the regulator in my mouth, adjusted the Infinium and slipped beneath the surface. I followed the sloping bottom down until it leveled off at about 15' feet and headed towards the dive platform located a short distance away. As when searching the beach area, I found that the Infinium's threshold remained essentially stable despite the fact that the site was littered with hot rocks. Signals were plentiful; however, recovering them required a little more effort than hunting with a scoop did earlier. I found that the best technique to use when diving was to "wiggle" the coil side-to-side by an inch or less and slowly push the coil forward. When the signal fades, stop moving the coil and use your hand to fan the sand/silt/mud away that is located at the rear edge of the coil. When you have freed the target from the bottom, the signal will once again be heard as it moves in the hole. Grab a handful of dirt and pass it over the coil. If you receive a signal, simply put everything in your mesh bag and move on to the next target. It took a few tries to get the hang of this in the pitch-black, muddy water, but signals become fairly easy to recover. After popping-up and reorienting myself a few times, I searched around the platform and the diving boards on the dam at the edge of the lake. Just over an hour was about as long as I could stay down and I started working my way back to the beach area.
Emptying out my pouch, I counted out 22 coins including 3 sliver dimes, one 1954 quarter, two sterling rings and a 10KT class ring. Turning up the heat in the truck, I started to warm up as we headed for home. I hit several other sites that had caused frustration in the past due to ground conditions and was rewarded with good finds at each one. The Infinium handled adverse conditions with ease and after getting the hang of pinpointing with the larger Double-D coil, target recovery was no longer a challenge.
The new Infinium LS incorporates the latest PI-technology and its performance in the field under a wide range of adverse conditions demonstrates that pulse units have come of age for many forms of treasure hunting other than only hunting saltwater beaches. If you are interested in a detector that is easy to operate and provides exceptional depth, stop by your local Garrett dealer and test drive one. It takes a bit to become proficient with; however, it has the ability to handle virtually any type of ground condition with little affect on its overall performance.
The Infinium LS lists for $1곚 and comes with the 2-year factory warranty. By the time this report is printed, there should be two optional coils available - an 8" and 10"x14" mono design.
For more information on any of the Garrett detectors or the name of your local Garrett dealer, contact the factory at 1881 W. State Street, Garland, TX 75042 or (800) 527-4011 or visit their informative website at www.garrett.com. Be sure to mention you read about the new Infinium in Lost Treasure!