Testing The Sun Ray FZ-12 Coil for Fisher CZ's
by Bill Ladd
(Reprinted with permission from Western & Eastern Treasures magazine March 2005 issue)
Finding old coins by the handful, the FZ-12 really proved its worth in the ground coverage.
In the hobby of metal detecting, having different coil choices can often be a big plus for certain types of treasure hunting. Although I own the 10.5" coils for most of my Fisher models, I longed for something even bigger for open fields that we search here in New England, and also for my yearly jaunt to the massive fields of the U.K. Covering as much ground as possible can lead to more productive hunting. Finally, Sun Ray Detector Electronics has come to the rescue with the introduction of the 12.5" FZ-12 Invader coil for the popular Fisher CZ line (with the exception of the original CZ-6 and the hardwired CZ-20).
The Sun Ray FZ-12 coil arrived while a hunting partner was receiving permission to hunt a farm field that had been plowed just the day before - perfect timing. We were excited, as this field had yielded Colonial relics and coins in the past. I have owned nearly every CZ model, but decided to mount the new coil on a CZ-6a that I have used for years. I was very surprised at its lightweight for its size! It's seemingly much thinner than the Fisher coils, in fact it weighs the same as the Fisher 10.5" coil. So, one can get 2" more ground coverage with the new Sun Ray, which adds up to a lot more "soil analysis."
Before meeting my partner at the site, I tried the FZ-12 at a soccer field, just to make sure that it acted and ground balanced like my stock coils. It was perfectly stable and balanced out at 5, which is usually the norm on CZ's in reasonable soils. I enjoyed the excellent sweep coverage I was getting, and the overall balance was very good as well.
The stock Fisher 8" Spider coil has always been my first choice for its versatility; it's good in trash, and not too heavy. However, I found myself having to be extra careful about overlapping my sweeps. Often I worried that I was missing targets by not taking "baby steps." The Sun Ray FZ-12 coil solved the problem. I now feel confident that I could cover an area twice as fast, without fear of skipping targets. After I dug a clad quarter that rang solid, followed by a deep Wheat cent, I was ready for the field.
It was a large cornfield that had been plowed only hours before, and this size coil seemed ideal for covering lots of soil in search of hotspots. It quickly proved that it had excellent sensitivity to small items, as the first few targets were small Colonial cuff buttons. The deepest item was an 18th century British copper that pinpointed at 8-9" with a solid "high tone" and correct target ID. Working this field, I began to get the feeling that serious relic hunters &/or cache hunters would certainly enjoy the FZ-12 coil.
My next test involved some serious, in-depth "freshly buried targets" alongside a Fisher 10.5" coil, using old coin targets at a construction site. Why a construction site? Well, this new neighborhood project involved cutting into a former forest, and thus offered me three very different soil types to work with at a single location - piles of topsoil they were to spread for lawns, the deeper clay layer that was bulldozed up, and dark forest soil. This time, I went digital with a CZ-7A, and for this head-to-head comparison, I brought along both coils on lower rods.
In this setting, I began to see some differences in the ground balance settings I was achieving. After some experimentation, my first test target in the clay was a Wheat cent packed down at a depth of 9". In this very harsh clay the Fisher balanced out at only 1. With the Sun Ray FZ-12, however, I got a better balance of 3, and there were no problems or chatter in the heavy clay. It also seemed a bit easier to pinpoint with the FZ-12 coil, since its center is not a solid elliptical, but rather a nice round, open "bullseye." In the mineralized clay the Fisher 10.5" coil just nipped the Wheat cent from one direction with a quick blip at certain angles. It was a signal that I would not have dug, and was only repeatable while pinpointing. Switching to the FZ-12, I was able to get a more pronounced signal that repeated from both directions. So, the Sun Ray got the nod for depth in harsh clay.
Author Bill Ladd works a wooded site with the new Sun Ray FZ-12 coil.
Next, I buried a Buffalo nickel in the darker lawn topsoil. It was buried close to 8" deep, and I was very curious to see if both coils would not only signal, but also ID it correctly, as occasionally deep nickels drop from Nickel to Tab. The Fisher 10.5" coil balanced in at 4, while the FZ-12 came in at 5. In this test, the Sun Ray coil gave a good, high tone from both directions, and solidly identified it as a nickel, with no "bounce." The 10.5" coil gave no audible tone, and only located the nickel in pinpoint mode. So, I was very impressed at the FZ-12's sensitivity toward the nickels in my area. Reports out of Florida say the Sun Ray is attaining even better depth with larger buried targets on the beaches there. Thus, I was satisfied after extensive tests in tough soils that it would exceed the 10.5" coil in most conditions. Also, remember that with the Sun Ray FZ-12 you're getting 2" more soil coverage at the same weight...another huge plus in my book.
My final outing was a search for actual, in-the-field targets rather than buried test coins. Conducted with the FZ-12 coil on a Fisher CZ-70, this hunt capped off the field test perfectly. I was invited to search the grounds of an old hospital. This was a coinshooting-type hunt, and I might have chosen a CZ to use here even if not field testing the coil. Knowing that I would be working for several hours, this time I chestmounted the CZ-70. This made swinging just the rod a joy even with a large coil attached. In doing this, I also noticed that Sun Ray offers an extra long cord length of 7' 6" for hipmount purposes, a welcome feature as it allows users more leeway to swing freely, and the cord can also be looped through your belt. This puts much less stress on both coil connectors, which is a definite advantage as most coil failures are due to connector problems.
Some detectorists may wonder if a 12.5" coil is too big for coin hunting. Well, in this case, not at all as the grounds were quite large, open lawns, and non-trashy - a perfect setting for any big coil. The place had been heavily hunted already, and the coins ranged from clad to the 1800s. I notched out iron and zinc, and my first target was a 6-7" deep 1930 Wheat cent. This same pattern continued as more Wheaties kept turning up, all 6-7" or deeper. I was hunting with two detectorists who were using 8" and 9" coils, respectively, and I was really covering more ground faster and more efficiently. Ordinarily, like them, I would have also been swinging a standard 8" coil, analyzing a lot less turf, and probably finding less. I think many folks believe that large coils are only for relic or cache situations, which is untrue. I also dug a 1935 Buffalo nickel and two Mercury dimes, the only silver coins found that day. I ended the venture with a handful of wheat cents and a couple of envious hunting buddies, and another successful field test was in the books.
As a serious treasure hunter, I welcome any accessories that can help me in the field.. I had been asking for a large coil for a long time, and the FZ-12 will now be a big part of my arsenal for open areas. I can only hope that more 12.5" coils will become available for my other Fisher units.
For further details on the FZ-12 Invader coil and other detector accessories such as the onboard probes, visit the Sun Ray website at www.sunraydetector.com or the Sun Ray forum at Findmall.com. You may also telephone Ralph at Sun Ray at (319) 636-2244.