F4 Field Test
By Andy Sabisch
From Page 14
January, 2007 issue of Lost Treasure

Fisher Research has produced metal detecting equipment longer than any other manufacturer and&#44 in the 75 years since it was founded&#44 has produced a number of detectors that set the bar in terms of features and performance that other manufacturers reached for in their detectors.

Started by Dr. Gerhard Fisher in his garage&#44 Fisher Research continued to grow over the years and in the early 1990s settled in Los Banos&#44 California. In early 2006&#44 the Fisher name and its assets were acquired by First Texas Holdings Company which already produced the popular Bounty Hunter and Teknetics lines sold worldwide and&#44 unbeknownst to many detectorists&#44 is actually the worlds largest manufacturer of metal detectors.
With the merger of Fisher Research with First Texas&#44 the company began to develop new detectors based on the technology available in both organizations. The Fisher F4 is the first of these new detectors that will be born from the joining of First Texas and Fisher Research. I have used a number of Fisher detectors since getting into the hobby more than 40 years ago and was anxious to see how this new model performed in the field.
Features The F4 is intended to go head-to-head with the mid-range detectors currently on the market&#44 and offers many of the features that detectorists have asked for&#44 including turn-on-and-go simplicity&#44 audio and visual target ID&#44 as well as having depth indication&#44 being lightweight&#44 and delivering good in-field performance.
The Fisher F4 utilizes the standard Fisher S-handle&#44 which has been well proven to be ergonomically designed&#44 and provides for hours of hunting without fatigue when combined with its sub-3 pound weight. It is a single-frequency detector that operates at 6.8 kHz. The stock coil that comes with the F4 is a 7x11 elliptical Double-D&#44 which was chosen for the electrical field it produces&#44 resulting in more complete coverage with each sweep (meaning fewer missed targets and more keepers in ones pouch at the end of the day) and smoother operation in more mineralized ground.
The housing features several well laid out touchpad controls and an easy-to-read LCD meter. The F4 is controlled via nine touchpads and a single knob all located on the face of the control housing. The touchpads include ON/OFF; ALL METAL/AUTO TUNE; PINPOINT; DISC(RIMINATE); NOTCH; DISCRIMINATION/THRESHOLD (+/-) & SENSITIVITY (+/-). The knob is used to adjust the Ground Balance to compensate for any mineralization that might be present.
The LCD meter provides a wealth of information that can be used to determine if a detected target is worth recovering or not&#44 as well as what the current settings selected are. In the center of the screen is a 3-digit numeric display that reflects the targets probable ID. The values range from 0 (highly ferrous targets such as iron) to 199 (large&#44 highly conductive targets). There is sufficient separation of targets within the available spectrum of IDs to allow users to readily differentiate a good target from a bad one&#44 with a little practice in a test garden or the field. In addition to the numeric target ID indication&#44 11 arrows on the upper portion of the meter provide additional information to help identify targets by pointing to labels of common targets that register in that region&#44 such as foil&#44 5c&#44 pull tabs&#44 screw caps&#44 zinc pennies and other coins. One can determine if a target is worth recovering based on the coarse indication (the 11 arrows) and then checking what the fine indication (the 0-199 numeric indication) shows. On the left side of the screen is a dual function display. When adjusting the SENSITIVITY via the [+] or [-] touchpads&#44 the indication switches to show what the current setting is. When detecting&#44 the display shows target depth from 0 to 10 in 2 increments. On the right side of the meter is a continuous display of relative battery strength which helps ensure you do not find yourself with a dead battery in the midst of a productive hunt.
The F4 provides users with three separate search modes along with a one-touch non-motion Pinpoint circuit. These include a true All Metal Autotune search mode requiring just a hint of coil movement&#44 a motion All-Metal search mode&#44 and a motion Discriminate search mode. The last two also provide audio and visual target ID indications when a target is detected.
A nice feature of the F4 is that you can quickly switch between the two motion search modes; i.e.&#44 All Metal and Discriminate&#44 by simply pressing the DISC touchpad. This allows you to go to All Metal to check a marginal signal received in Discriminate and determine if there might be trash partially masking the signal&#44 or if it is a large piece of trash trying to fool the detector. This feature proved to be quite useful at several sites I searched. The Discriminate mode also provides NOTCH discriminatio&#44n which means you can easily accept or reject any of the first seven segments. This allows specific trash targets to be rejected while still accepting targets that read lower on the meter&#44 thereby not missing potentially valuable items because you opted to reject a piece of trash which will happen on a non-notch detector.
If you want to hunt in the Autotune All Metal mode&#44 you can use the DISCRIMINATION/THRESHOLD touchpad to adjust the audio threshold. This is useful when searching for very small or deep targets and often the only indication you receive is a fluctuation in the threshold signal. While not designed to be used primarily as a prospecting detector&#44 the F4 equipped with the 4 concentric coil is surprisingly sensitive in the Autotune All metal mode based on tests conducted on small nuggets and lead shot.
Ground balancing a metal detector is probably the most feared adjustment any detectorists might have to make; however&#44 the F4 makes that task quiet simple. Simply press the ALL METAL / AUTO TUNE touchpad&#44 then raise and lower the coil near the ground. If you hear any response&#44 slowly adjust the Ground Balance knob until there is very little or no change and the F4 is ground balanced.
The F4 is powered by two 9-volt batteries which provide approximately 25 hours of operation. NiMH cells can be used with no adverse effect on performance. There is a stereo headphone jack in the bottom of the control housing which accepts any set of stereo headphones&#44 and their use will extend overall battery life.
Field Test After checking targets on the table and in my test garden&#44 I headed out to a few parks to see how it performed in areas where targets were numerous both trash and treasure and ground conditions were a challenge for some detectors. Starting near several picnic tables in the factory preset discriminate mode (which only rejects the iron signals)&#44 I quickly saw there tin foil and pull tabs I would have to contend with. Pressing the DISC touchpad&#44 I rejected the FOIL segment then&#44 using the NOTCH touchpad&#44 rejected the PULL TAB and SCREW CAP segments. Continuing on&#44 I found the F4 was doing a great job ignoring the trash targets I had told it to and&#44 even with the detector set that way&#44 I recovered several nickels from amongst the trash...all producing solid&#44 repeatable signals that indicated correctly on the LCD meter. It did not take long before I was able to get a good idea as to what I had detected based on the audio target ID response before even checking the numeric ID displayed in the meter. A few hours at three different locations netted me several dollars in change&#44 along with pieces of costume jewelry&#44 sets of car keys (always wonder how people get home when I come across these) and assorted goodies to add to my collection. The NOTCH circuit had eliminated better than 90% of the trash&#44 leaving only the tabs that registered close to nickels and larger trash&#44 such as pieces of aluminum cans that hit much higher on the meter.
Opting to see how the F4 performed at an older site&#44 I took it to a wooded area where an old house had once stood. There was a good deal of deep rusted iron&#44 which plays havoc with most detectors&#44 and the F4 did stumble a bit under these conditions as well. In order to reduce the chatter from the iron&#44 I dropped the sensitivity and rejected the first three segments. While the Double-D coil was trying to handle the mineralized ground and ferrous targets&#44 I think the size of the coil may have overwhelmed the F4s circuitry a bit so&#44 after recovering a few non-ferrous targets (two modern shotgun casings and a button from the late 1800s)&#44 I opted to try the concentric coils and see how they performed. T
he 4 concentric which is included with the F4 ran virtually silent with the same settings I had used the Double-D coil with. Obviously detection depth was less; however&#44 I was able to increase the sensitivity setting to near MAX and the smaller coil did allow me to get into areas between foundation stones or beneath fallen trees that a larger could would not have reached.
Several keepers turned up from depths down to 6 inches&#44 including a 1926 Wheat cent&#44 a dateless Buffalo nickel&#44 a silver-plated spoon and two more buttons. Deciding to give the optional 8 concentric coil a try before heading home&#44 I switched coils and hunted the open area in front of the foundation. The smaller concentric coils seemed to be the secret at this trash-laden site as even the 8 coil was quiet and easily detected targets down to the 8+ mark.
Over the next two weeks I tried the F4 at several locations and found that having the flexibility of both concentric and Double-D coils to choose from made the F4 very versatile in being able to handle ground and trash conditions that ranged from clean&#44 fairly neutral soil to iron-infested and highly mineralized clay. The consistency in the target ID numeric values seemed to drop off a bit as targets went below the 6 mark&#44 but this is not uncommon even on more expensive target ID detectors.
Summary The new F4 takes the Fisher line in a new direction in terms of appearance&#44 construction and features at its MSRP price point. Some purists will dismiss the F4 as not being a true Fisher detector based on past models&#44 but&#44 as they say&#44 nothing is constant except for change and the F4 is just one indication of the changes underway at Fisher Research. Melding technology from both the First Texas and Fisher lines will result in new innovations for both brands.
The F4 may even appear to be similar to the Discovery 3300; however&#44 in addition to the new Double-D coil&#44 internal changes such as the Autotune mode&#44 increased sensitivity and improved target separation puts the F4 on a different plane than other detectors in the current First Texas (Bounty Hunter / Discovery / Titan&#44 etc.) line-up.
The Fisher F4&#44 with both the 11x7 Double-D and the 4 concentric search coils&#44 lists for $499 with the new 5-year Fisher warranty. There is also an 8 concentric coil available as an option for those that prefer concentric coils for the areas they hunt.
For more information about the new F4&#44 the rest of the Fisher line&#44 or the name of your nearest Fisher dealer&#44 contact the factory at 1465-H Henry Brennan; El Paso&#44 TX 79936&#44 call them at (800)-685-5050&#44 or visit their website at Be sure to mention you read about the new Fisher F4 in Lost Treasure magazine.

F4 Field Test

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