New Detector Produces the Goods!

CHRIS GHOLSON

 Pausing for a moment atop a high mesa I could see that the sun had already begun climbing its’ way over the horizon. Rays of yellow light streaked across the mountains below suffocating a pale moon which remained barely visible in the distant western sky. I rolled down the window of my truck allowing a cool waft of morning air to fill the cab. This had been one of Arizona’s wettest winters in recent times; a welcome change from the past ten years of drought. It is amazing the profound effect a little moisture can have on a desert. Looking back a few months ago on what was once a parched escarpment of nearly barren granite had miraculously been transformed into what can only be described as an oasis. Staring through the windshield I saw the broad, green leaves of the Cottonwoods along the creek fluttering in the breeze, I noticed thousands of blades of lime colored grass had erupted forth from the soil, and wildflowers of all varieties had marched across the hillsides splashing color on the usually drab landscape. It was a beautiful site, and one I probably could have enjoyed even more had the blasted dirt road not been so rough! The rains had brought new life to the State, but they had also brought mass destruction to many of its’ back-roads. There was simply no way to avoid the countless ruts that had gouged away the narrow track. The poor diesel truck and its driver (me), bobbed up and down like a buoy in an Atlantic storm. Luckily the constant pounding would not last much longer; I had nearly reached the test site. 

Once at my destination I shot a quick glance over my shoulder towards the backseat. All was well. A shiny, metallic blue box inscribed with the letters GP3500 was still there resting quietly. A few weeks prior I had received a call from Minelab Electronics asking if I would be interested in field testing their newest most advanced gold machine; the GP3500. It was a tough decision I can tell you, taking me all of two seconds to make up my mind! As excited as I was, I had serious reservations as to whether this new contender could match that of my trustee GP3000. The “35” would need to leave a lasting impression if I was to even consider abandoning a machine that had netted me well over a thousand nuggets.

The stock 11” Double D coil supplied with the 3500 handles ground mineralization like a charm and is great for picking shallow targets. Alas, I have never been one to be satisfied with stock parts. One of the first things I did was remove the 11” DD and replace it with a Nugget Finder 16” Super-Lite monoloop coil, a tool I knew would offer more ground coverage and triple my depth penetration. Next I swapped out the standard 6V Gel Cell battery for one of Reed’s Lithium Ion Systems; a 12V power supply with only half the weight. Then, off came the stock neoprene armrest cuff and in its place was fitted a camouflage replacement cuff. Finally, I wrapped the entire control box in a protective AZO Camo Box Cover. Now I was ready to tackle the terrain! 

With detector in hand, I slowly made my way towards the once rich nugget patch, keeping a sharp look out for rattlers lurking amongst the Amazon-like weeds. I won’t give the exact location, but this particular spot has been very popular among nugget hunters over the years. Hundreds of people have scoured its’ slopes with everything ranging from the original Garrett Groundhogs to the newer PI models we have today. Chances of pulling a nugget were slim, but this was exactly the sort of place I aimed for when testing new equipment. In my opinion, it is pointless to go exploring virgin country on a field test. Sure, you can gain a feel for how the machine performs, but it won’t answer the most important question of all “Is there an advantage on old patches?” No, the best way to determine a machine’s true capabilities is by running it on ground that has been hammered to death. 

After a few swings I was pleased to discover that even with a mono coil and running in the Fixed position, the machine was able to cope with the iron-rich, red soil with little trouble. However, the ground varied just enough to warrant experimentation with the new adjustable Tracking Speed feature (we’ll discuss this in more detail later). I began first in Slow mode then gradually worked my way into Medium. I managed a few “wishy-washy” shallow pieces of iron that appeared to have come off a bull dozer blade. They were only buried 3-inches beneath the surface, and as expected they were not balanced out. I pressed on gravitating towards an area where I pulled several nice nuggets in 2003. An hour passed and nothing. More time slipped by and still no miracles.

Finally, to my great relief, something did happen. A little rise in the threshold caught my ear. It wasn’t much of a signal, but I could tell something was upsetting the steady background hum. I pushed the balance button on the handle, switching momentarily into Fixed to help pinpoint its location. Truthfully, it sounded like a small target, maybe four inches deep. I booted a few rocks to the side and scratched away the top soil. The sound didn’t really improve; behaving now more like a pocket of hot ground than a metallic target, but I kept digging to satisfy my own curiosity. I gradually dipped the coil back into the eight inch deep hole, praying it had not vanished. Still there! It got to the point where I could no longer dig any deeper without widening the hole. I chipped and pried, cussed and swore that if this was a tin can there would be hell to pay! The hole widened and continued to get deeper, all the while the mystery target increasing in strength. Finally I dropped to my knees and extended my arm full length into the hole, scratching at the bottom and pulling loose material into the heap.

I waved the coil once more across the hole; this time it was silent. I edged it towards the pile and was greeted with an ear-splitting overload! The moment of truth had come; it was out. The target was much too large to pinpoint so I shuffled handfuls of dirt across the coil. Grabbing up a fistful of fresh soil I felt something oddly heavy. I loosened my grip allowing the rest of the dirt to fall to the ground. My hands trembled slightly as I slowly opened my fingers. I didn’t need to wash away the ancient red clay that clung to its’ surface to recognize this object was a lump of gold – 5 ounces to be exact! I leaned back on a nearby boulder and laughed like a lunatic that had just found a winning lottery ticket! I didn’t have a tape measure, but the hole was nearly as long as my arm. My best guess was 2-feet in mineralized soil. Even after repeated sweeps in the Tracking mode the 3500 did not balance out the nugget. In fairly homogeneous soil I will most likely hunt in Fixed, however it is nice to know that if I do opt for the Tracking feature I’ll have less chance of leaving deep targets behind for someone else.

Despite the obvious similarities in color and general design with other GP Series machines, several noteworthy changes have been made to the 3500. The first addition that had me praising the Australian techies was the placement of the ground balance switch into the handle. Brilliant move Minelab – two thumbs up! With the ability to adjust for varying soil conditions right at my finger tips, I no longer found myself dreading this procedure. When reground balancing both the GP Extreme and 3000, you had to bend over, flip the switch from Fixed into Tracking, pump the coil over the ground, wait for the noise to die down, and then flip back into the Fixed position. The 3500 eliminates all of this with a simple push of a button. Not only is it more convenient, but frequent rebalancing strengthens target responses and improves the chances of hearing faint, or deeply buried objects. For me, this “quick-balance” is a big bonus, especially when searching in the Fixed position.

Undoubtedly the biggest improvement on this detector was giving the operator the ability to adjust the Tracking Speed. When the Balance switch is placed in the Tracking position, the 3500 continually adjusts to minimize the effects of changing ground mineralization. Minelab has used this technology in several earlier models and it works really well – sometimes a little too well! Many prospectors, myself included, found that the SD2200d, GP Extreme and GP3000s would in some cases actually balance out a very deep target when the coil was repeatedly passed over it. Very tiny nuggets or those hidden beneath a foot or more of soil tend to produce more of a “whisper” rather than a well defined signal response. If the signal generated isn’t strong enough to pause the auto ground balance it can be interpreted as nothing more than ground noise and will be balanced out. With these earlier machines we were stuck with the factory settings, but now with the 3500 this power lies within the hands of the operator. On noisy clay or washes carrying heavy black sands, it is now possible to run the Tracking Speed in Slow or Medium without fear of balancing out a potentially deep nugget (something I proved for myself during the field test). The Fixed position offers maximum depth, but there are many situations where the Tracking mode gives better results.

I have also found the 3500 to be more immune to external interference. Airplanes and distant power lines plagued my 3000; especially when the coil was turned on edge. The 3500 still picks up noise from these sources, but not nearly as bad. Call me crazy, but this detector seems more stable than any Minelab I’ve used before. Another observation is that unlike the 3000, the 3500 seems to perform best when ran in Deep (Boost switch) and Normal (Soil switch), as opposed to Deep and Sensitive. The Auto Tune also seems more proficient at locking onto quieter operating frequencies than the 3000.  

My one dislike is the incorporation of the On/Off switch onto the Threshold control. This one knob is now used to both activate the detector and set the Threshold level. The Soil switch on the GP3500 is in exactly the same place as the On/Off switch was on the GP3000 and Extreme. Old habits are truly hard to break because I find myself continually flipping the Soil switch on the “35” in an attempt to turn it on and off. It also seems unnecessary to always have to readjust the threshold each time the detector is turned on. This dual purpose control does not affect the detector’s ability to find gold, but it will take some getting used to.

Since unearthing the 5-ounce nugget, I have made several other expeditions into the goldfields, each trip growing fonder of the 3500. In the short time I have owned the detector I have pulled a dozen nuggets all from locations I have searched before. Would the previous Minelab SD and GP machines have found these treasures? Maybe…maybe not. All I know for certain is that these nuggets were still there. The differences between the GP3000 and the 3500 may not be monumental, but from the viewpoint of a serious prospector that relies on new technology to gain an edge on the competition, this is irrelevant. Regardless of how subtle these advantages may be, they are in fact advantages.

If someone were to ask me my personal opinion I would reply that this is the finest gold machine currently available. I say this because, 1) it has the ability to punch through heavily mineralized soils with ease, 2) it can ignore a majority of the hot rocks found on the goldfields, 3) eliminates the likelihood of balancing out targets at depth, and 4) can reach depths electronic prospectors twenty years ago would have never dreamed possible. The GP3500 is an incredible piece of equipment, but potential buyers must always keep in mind that this machine cannot make the gold. Even with superior performance the real burden falls upon the operator. They must be willing to put in lots, and lots of hours behind the coil and stay positive even after digging their hundredth bullet of the day. Tracking down this precious element is difficult, but not impossible. The gold is out there and I honestly think it is attainable by anyone with quality equipment and above all else, the proper mindset. Patience and determination, coupled with a metal detector such as the GP3500 is definitely a winning combination.