Treasure Hunting Forum

I finally received the Fisher F75 on June 11. After unpacking, I found the machine easy to assemble and of very good quality. Its design is ergonomically pleasing as well – elbow rest and wand length are each adjustable to individual preferences. Good weight distribution facilitates a free and easy scan cycle with the waterproof elliptical search coil; total weight of 3.5 pounds should permit hours of tireless hunting. Using four AA batteries, the machine is projected to go 30 hours between changes; that’s as good as any machine I know of. A battery charge indicator is in constant view on the LCD screen.

Before putting the new Fisher F75 on the ground I read and reread the instruction manual and then gave the detector an air test. The manual is well written and very thorough, and the air test convinced me that the F75, at the highest sensitivity setting, has the potential for better depth capability than any detector I’ve yet used.

The machine’s backlit LCD screen contains the entire mode and function menu. After only a bit of practice I was able to set the machine up in all three of its search modes – “static all-metals,” “motion all-metals,” and “discrimination” – and personalize individual functions in each mode, e.g., sensitivity, discrimination level, notch discrimination, audio tone variations, threshold level, etc. The menu-driven interface is exactly what Fisher claims – intuitive. Once you become familiar with the terminology and the response to the menu button and settings knob (that’s right, only a button and a knob are used to set up all the search modes and the individual functions), initial setup and fine-tuning is a snap. A toggle switch is used for pinpointing and for other functions.

The method used by Fisher to identify the target is most intuitive. At the top of the screen is a row of words entitled “iron,”, “foil,” “tabs,” “zinc,” “dime,” etc., over which a slash appears to ID the target. There is an adjacent vertical bar that indicates confidence level (a measure of how sure the detector is that it is making a correct ID), another that indicates depth, and still another that indicates ground mineralization (percent magnetite). And Fisher uses still another slash over the target identifiers or a small line through them to show zones of discrimination as well as the zone of notch discrimination, if used. So a glance at the row of targets gives you information about the target identification and also shows the level of discrimination and notch (in or out) that the machine is employing.

There are four “processes” that can be used in discrimination mode, “default,” “jewelry,” “bottle cap,” and “plowed fields,” and a number of other minor features that contribute to the outstanding flexibility of the machine, but which will not be discussed here. Operating frequency can be shifted from the standard 13 KHz in cases where electrical interference is a problem. Ground balance may be obtained by Fisher’s “Fast-grab” system or by manual tuning.

So… After familiarizing myself with the machine and the recommendations from the manual for setup, I set out to experience firsthand its performance. I can now report on three field trips, one being a coin hunt to the extinct 1820s town where I tried the Explorer SE, the other two to the hills along Confederate lines here in Vicksburg where I searched for relics. 

The positives:

1. Fisher’s “Fast-grab” system for setting ground balance works like a champ. Nothing could be easier, and it can be quickly reset by merely pushing the toggle switch forward and slowly “pumping” the coil above the ground. There was no need to manually tune the ground balance.
2. Target pinpointing is quite easy with the toggled “pinpoint” mode.

The negatives:

1. The initial search for coins in the extinct town was disappointing. Setup as directed for an initial hunt (sensitivity 60, discrimination level 10, number of tones 3, process # default), the only signals were iron. I gradually increased the sensitivity until I was at maximum (99); background noise increased considerably, but no coins or non-ferrous targets were identified or dug. It should be noted that this area has been hunted frequently.
2. I found the LCD upper target ID line a bit too close to the top lip of the control box – I had to constantly raise the detector to see it clearly, and in the process many times the detector saw another target and the original was lost.
3. An attempt to judge the size of a target while in the discriminate mode is difficult. The response to several buried cans was more like a coin than a huge target. However, size was quickly determined by pulling the toggle switch to place the detector in pinpoint or static all-metal mode.
4. Sadly, it soon became apparent that the tremendous depth detection of which the F75 is capable in all-metal mode is severely limited when the detector is placed in discriminate mode. It was soon obvious, too, that, more than with any other machine I have used, the coil of the F75 must be moved very rapidly in order to achieve maximum depth. Careful scanning with the F75 is a recipe for lost targets.
5. The location of the power/volume knob under the left side of the elbow rest allows it to be accidentally repositioned by contact with body or clothing. This happened several times while I was hunting.
6. The search of the hills in Confederate lines was disappointing as well. Whereas only days before in this same area I had dug the wreath portion of a CS buckle and several minie balls, I dug not even a minie with the F75 in two trips.

Conclusion:

Though the F75, with its superior design and sensitivity, has tremendous potential for relic hunting, this potential was not realized in my three field trips. This is not to say that the results of future hunts will be the same – and I intend to continue to use it for relic hunting unless the time comes that its inadequacies are well established. I have not tried the detector for coin hunting at house sites or parks, and it is there, I believe, that the detector has the most potential for superior performance. I will also give it the opportunity to locate some of the deeply buried artillery shells that abound in Vicksburg, and there, too, it has the potential for excellence. I will probably not utilize it for gold prospecting, though beach and shallow water hunting is in the cards. I will report my opinion in these spheres when that time comes.

This entry was posted on Sunday, June 24th, 2007 @ 9:49 pm on the category Metal Detecting.You can follow any responses to this entry through the RSS 2.0 You can skip to the end and leave a response. Pinging is currently not allowed.