Fisher F75
Fisher F75 Target ID Chart: Reading 0 to 99 in Iron and Mineralised Ground
Quick answer
Fisher publishes a 0 to 99 numeric target identification display for the F75. Iron reads below about 20, nickels near 30 to 40, pull tabs 40 to 55, clad and copper coins 60 to 80, and silver from roughly 78 to 95. On the F75 the mineralisation bar graph tells you how far to trust any of it.
The Fisher F75 is a relic machine that happens to be very good at coins, and its reputation rests on two things: an unusually light build and fast recovery between targets in iron. Fisher publishes a large LCD screen with 0 to 99 numeric target identification, trigger-actuated FastGrab ground balance, double-filter discrimination modes and a magnetic mineralisation bar graph and readout.
That mineralisation readout is why the F75 deserves its own chart rather than a footnote on the F44 page. It is the only control on the machine that tells you, before you dig anything, how much confidence the number on screen actually earns.
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Fisher F75
Fisher publishes a 0 to 99 numeric target ID, a magnetic mineralisation bar graph and trigger-actuated FastGrab ground balance on the F75, which together let you judge the reliability of the ID rather than just reading it.
Price was accurate when this page was compiled and changes often.
On this page
What does the mineralisation readout change about the chart?
The magnetic mineralisation bar graph is a running measure of how much iron oxide is in the ground under your coil. It is not a target reading. It is a confidence meter for every target reading that follows.
In low mineralisation the F75 target ID is genuinely dependable, and the bands below will hold reasonably tightly. As the bar climbs, the ground itself starts contributing signal, target IDs sag downward, depth falls, and the honest working range of the chart narrows from a few points of error to something much wider. On badly mineralised ground a silver dime at seven inches may simply not produce a number worth reading.
This is the correct order of operations on an F75: ground balance with the trigger, read the mineralisation bar, then decide how much weight to give the ID. Most people skip straight to the number, which is how a good machine gets blamed for the dirt.
What does each target read on an F75?
Bands, not values, and expect them to compress downward as the mineralisation bar climbs.
On an F75 in low mineralisation, coin targets hold within a few points of these bands, and in high mineralisation the whole scale sags downward by ten points or more.
| Target | Typical F75 ID | Behaviour in iron | Notes |
|---|---|---|---|
| Nails and small iron | 1 to 15 | Grunts, broken | The F75 is fast enough to separate these from good targets |
| Large corroded iron | 1 to 20, spikes high | Falses upward from one angle | Cross-sweep. Flat iron is the classic relic-site trap |
| Steel bottle cap | 20 to 60, unstable | Repeats poorly | Instability is the tell, not the number |
| Lead shot and small lead | 20 to 45 | Clean, short | Lead reads across a wide band. Dig it on old sites |
| Foil and small gold | 18 to 40 | Quiet, easily masked | No number identifies gold on any machine |
| US nickel | 28 to 40 | Stable when shallow | The best calibration target you can carry |
| Brass buttons and small brass | 35 to 60 | Clean | Relic band. Discrimination here is expensive |
| Pull tab | 38 to 52 | Clean | Overlaps mid-size gold rings |
| Zinc cent | 56 to 68 | Fades early when deep | Corrodes badly, reads low when old |
| Copper cent and large copper | 66 to 80 | Strong | Patina pulls the number down |
| Clad dime | 68 to 80 | Thin, fades earlier than a quarter | Reads under silver of the same size |
| Silver dime | 76 to 86 | Strong | Deep silver drops into the copper band |
| Quarter and silver quarter | 80 to 90 | Strong, wide | Large flat iron imitates this band |
| Half dollar and larger silver | 88 to 95 plus | Very wide signal | Check the footprint before committing to the hole |
Fisher publishes the 0 to 99 numeric target identification display for the F75. The per-target bands are the consensus of owner reports rather than a Fisher specification, and they shift with mineralisation, depth and corrosion.
Why does the F75 get recommended for iron-heavy sites?
Recovery speed. When two targets sit close together, a detector has to finish processing the first before it can report the second, and the time that takes decides whether you hear one signal or two. The F75 is quick, which is why it keeps appearing on old house sites and military camps where the ratio of iron to everything else is brutal.
Fisher pairs that with double-filter discrimination modes, which change how the machine handles ground and trash rather than simply blocking ID bands. The practical result is that you can run the F75 fairly open in iron and still pick the good target out of the noise, which is the opposite of the usual budget-machine strategy of discriminating heavily and hoping.
The cost is that an open machine on an iron site is loud and tiring. This is a detector that rewards headphones and rewards a slow sweep, and it punishes anyone trying to cover ground quickly. Fisher also states typical operation of forty hours or more on four AA alkaline cells, so long sessions are at least not a battery problem, and a set of Rechargeable AA NiMH Batteries, 8 pack makes that cheaper still.
How do you build a reliable F75 test garden?
- Choose representative ground. Pick a patch of your own soil that resembles the sites you hunt. A test garden in imported topsoil tells you about imported topsoil.
- Bury known targets at marked depths. Nickel, zinc cent, copper cent, clad dime, silver dime if you can spare one, quarter, pull tab, bottle cap and a nail. Place each at two, four, six and eight inches and record the layout on paper.
- Wait for the ground to settle. Freshly disturbed soil reads differently from undisturbed soil. Give it several weeks and a few soakings before you trust anything it tells you.
- Ground balance with the trigger first. Use FastGrab over clean ground next to the garden, then note where the magnetic mineralisation bar sits. Record that number with your results.
- Record the ID at each depth. Write down the number, whether it was stable, and what the tone did. Repeat from ninety degrees and record that too.
- Repeat in wet conditions. Run the whole garden again after heavy rain. The difference between your dry and wet numbers is the honest error bar on every chart you will ever read.
Where does the F75 sit against the rest of the Fisher line?
The Fisher F22 and Fisher F44 are coin machines with short menus, aimed at parks and general use. The F75 is the one you buy when the ground has beaten those machines, either through mineralisation or through sheer density of iron. It is also the one that asks more of the operator, and it will not out-find a well-used F44 in a clean park.
For gold prospecting specifically, the higher frequency Fisher Gold Bug Pro is the right tool in this family, and the Fisher Gold Bug 2 goes further still. Neither replaces the F75 as a relic machine.
If you are deciding between them, the F44 chart and the Gold Bug Pro settings chart lay out what each machine is actually for, and the Teknetics G2+ chart covers a closely related machine at a lower price. For the wider field, see the comparison hub or the expert setup.
Sources
- Fisher F75 owner’s manual, target ID, ground balance and discrimination sections
- Fisher Research Labs published F75 specification, 0 to 99 numeric target identification display
- Fisher F75 manufacturer listing bullets, mineralisation bar graph and battery life
Frequently asked questions
Does Fisher publish a target ID range for the F75?
Yes. Fisher states a large LCD screen with 0 to 99 numeric target identification display in its own published description of the F75. That is a manufacturer figure. What Fisher does not publish, and what no manufacturer publishes, is a table of which number each coin produces, because that depends entirely on depth, soil, orientation and the condition of the target itself.
What does the magnetic mineralisation bar graph tell me?
It measures how much iron oxide is in the ground under the coil, which is the main thing degrading both your depth and your target ID accuracy. A low reading means the ID numbers are dependable. A high reading means IDs will sag downward, depth will fall, and you should widen your dig criteria rather than trusting the screen. Read it before you judge any target on that site.
Why is the F75 recommended for iron-infested sites?
Recovery speed. Detectors need time to finish processing one target before reporting the next, and the F75 is quick enough to separate a good target sitting beside a nail rather than blending them into a single confused signal. Combined with the double-filter discrimination modes Fisher publishes, that lets you run the machine fairly open in iron instead of discriminating heavily and losing finds.
How long do batteries last in a Fisher F75?
Fisher publishes a typical operating figure of forty hours or more on four AA alkaline cells, which it describes as a low operating cost. Real runtime falls with the backlight on and with heavy headphone use. Worth knowing: low cells change how a detector behaves before they stop it working, so swap them at the first hint of odd behaviour rather than waiting for the machine to die.
Will a deep silver coin still read in the silver band?
Often not. Depth pulls target IDs downward on every VLF machine, and mineralisation pulls them down further, so a silver dime that reads in the low eighties near the surface can read in the sixties when it is deep. On old sites this is the reason experienced users dig repeatable mid-range signals that a beginner would dismiss as copper cents.
Researched, not professional advice. This page is compiled from published specifications, manuals and owner-review consensus, not hands-on testing. Target ID numbers, depth figures and settings vary with soil chemistry, moisture, target size, depth, orientation and firmware version, so treat every figure here as a starting point and verify it against your own machine's manual and your own ground. As an Amazon Associate we earn from qualifying purchases.