Salt-Water Hunting. Fisher Research Labs F75 SPECIAL EDITION

F75-MANUAL(122811).qx 12/14/12 9:03 AM Page 4

F75

Comprehensive Operating Manual & Guide to Metal Detecting

Specifications

Mechanical:

Searchcoil:

Batteries:

S-rod with electronics housing mounted on handgrip, 3-piece breakdown, batteries under elbow, 2-way armrest adjustment — forward/backward & around forearm.

11” (28 cm) open-frame elliptical double-D, waterproof.

4 AA, alkaline (not included).

Weight:

Static Balance:

Dynamic Balance:

3.5 pounds (1.6 kg) with alkaline batteries installed.

force in vertical plane normal to elbow 0.47 pounds (0.22 kg).Varies

with adjustment and user’s stance and arm/hand physiology.

axial moment, 0.29 foot-pounds (0.39 newton-meters). Varies with adjustment and user’s stance and arm/hand physiology.

Sweep Effort:

Operating Principle: lateral moment 5.2 foot-pounds (7.1 newton-meters).

VLF induction balance

Operating Frequency: nominal 13 kHz, quartz crystal timing reference

13158Hz, 13100Hz, 1043Hz, 12987Hz, 12931Hz, 12876Hz, 12821Hz

Basic Sensitivity: 6 x 10

9 root Hertz (detectivity)

Lag Coefficient:

Reactive Overload:

Resistive Overload:

78 milliseconds approximately 10,000 micro-cgs units (volume susceptibility)

40,000 micro-cgs units with sensitivity < 30.

approximately 1,200 micro-cgs units (volume susceptibility)

4,800 micro-cgs units with sensitivity < 30.

Ground Balancing Range: From ferrite to salt, inclusive

Discrimination

Ground Suppression: combination of second and third order methods

ID Ground Suppression: third order

Battery Life: Typically 40 hours with high quality alkaline batteries

Estimated 80 hours with nickel oxyhydroxide batteries

Estimated 65 hours with lithium iron disulfide batteries

Operating Temp Range: 4 to +122 degrees F (-20 to +50 degrees C)

Operating Humidity Range: 0-90% non-condensing

4

F75

Comprehensive Operating Manual & Guide to Metal Detecting

Detecting Activities (continued)

Shallow Water Hunting (continued)

When searching on a beach, it is best to either search in Motion All Metal mode, or to search with the discrimination level set just high enough to eliminate iron, because the value of beach finds is largely in the jewelry rather than in the coins. You will dig a lot of aluminum trash, but the digging is easy, and you can tell people that you are helping to clean up the beach and make it safer for people's feet. We recommend the use of a special sand scoop for recovering valuables from the sand quickly -- most metal detector dealers sell these.

The electrical conductivity of the water itself can pose some challenges. You may get false signals when going into and coming out of the water, making it necessary to pay careful attention to keep the coil either in or out of the water, but not to touch the surface. This effect may be observed in either fresh or salt water.

Salt Water Hunting

Salt water is highly conductive, and produces a strong signal which is like that of metal.

The F75 is not specifically designed for high performance in salt water, but can be used in this environment.

If you desire to search in or over salt water, the following measures will usually be sufficient to silence the salt water response while retaining acceptable sensitivity:

1. Set the sensitivity in both modes to less than 30.

2. Ground balance the machine manually in Motion All Metal mode.

3. Search in the Discrimination mode with a discrimination setting higher than 25.

Treasure Hunter’s Code of Ethics:

• Always check Federal, State, County and local laws before searching

• Respect private property and do not enter private property without the owner’s permission.

• Take care to refill all holes and leave no damage.

• Remove and dispose of any and all trash and litter found.

• Appreciate and protect our inheritance of natural resources, wildlife and private property.

• Act as an ambassador for the hobby, use thoughtfulness, consideration and courtesy at all times.

• Never destroy historical or archaeological treasures.

• All treasure hunters may be judged by the example you set; always conduct yourself with courtesy and consideration of others

Copyright Fisher Research Labs, Inc. 2011.

41