Fisher F70

Here is some info on the Fisher F70. I don't want to re-write the manual here so I just try to point out what's special about the F70 compared to other detectors.

For those who don't want to read everything that is on this page here's the short form:

Is the F70 as deep as the Fisher F75 ?

Yes it is if you know how to set it up right.

But the F70 has less features you may want than the F75.

Here's what the F75 has over the F70:

• 11“ DD biaxial coil that cuts better between targets and is deeper in high mineralized soil.

• Arm rest can be squeezed to fit your arm

• Thicker grip

• Static All Metal Mode

• DE, JE, BC and PF prozessing modes

• Automatic and manual GB

• Thicker display screen

• Backlight (always on)

• „depth on the fly“ meter

The F70 has features the F75 doesn't have:

1. If you set the F70 to speed SLOW it has the same punch as the F75 in the hot JE processing.

2. The F70 can fastgrab over salt in the All Metal mode, on the F75 you have to do it manually if the ground number is lower than 40.

3. If you set the F70 to DE speed it is DE no matter where you have your disc setting.
   On the F75 it seems it has slow (JE) from disc 0 to 4 and fast (DE) from 5 to 19 and after 19 JE (slow) again. So DE processing on the F75 seems a mixture of the DE and slow speed of the F70.

4. You can set the DE or Slow speed in the All Metal Mode too. F75 has only one speed in motion all metal.

5. Easier to use interface

Here's the best part

On the F70 Gain (labeled sensitivity) and Threshold together contol the power of the F70 in Disc Mode. In the perfect ground and no electrical inteference we would like to run Gain and Threshold high for max. depth.

But since power lines or bad ground limits the use of high gain or threshold let me explain how it can be used to get good depth under the worst conditions.

Since Gain contols the size of the magnetic field of the coil the more you turn it up over bad soil the more the minerals are seen and fire back into the magnetic field of the detector. Like using high beem in fog. You see less because the light is reflected by the fog.

Threshold boosts the received signal by the coil. So if you have an overloaded signal because of to much gain, high threshold makes it worse.

Now how do you know how to set gain (sensitivity) and threshold ?
Just watch the FE3O4 gauge. If it is high go with lower gain and higher threshold. I was able to get good depth in really bad soil by setting the gain to the lowest setting and threshold to max.

Also the FE3O4 gauge can be used as an indicator when to switch to the All Metal Mode which is the deepest mode even in bad soil. You lose tone ID but you still have VDI numbers.

The secret to depth in disc mode on the F70 is the right balance of Gain (labeled sensitivity) and threshold for the type of ground you hunt. Speed is important too. Please don't ask me : „What is the best combination of these controls ?“, because these is no answer to that. Your soil and surroundings define the settings. Bury a coin in your soil and play with these settings to check out what works best !

Examples of gain(sensitivity) and threshold settings:

I live at a home with Power lines right over it and the ground is heavily mineralized. A coin buried at 8 " in my backyard could not be detectet with the settings I startet with:

Sens 60, Threshold -3, Speed DE, Disc 10.

I tried to switch to Speed slow to get more punch, but the detector picked up the interference from the power lines.

I switched back to de and played with the disc settings. I found out that at Speed De and Disc at 0 some more punch kicks in but some interference came back too. Next I set the gain (sensitivity) back to 30 and the threshold + 5 and the detector was able to pick up the coin without interference right under the power lines.

Here is an other setting that picked up the coin without interference:

At (Auto Tune All Metal), Speed De, Threshold - 3, sensitivy 60

The advantage of the Disc 0 setting was that I still had tone ID.

On other places without power lines and better soil I got extreme depth in Disc 0 or At, Speed slow , threshold - 3, sensitivity higher than 80 some times. Depth of over 14 inches on a coin in the ground is possible. Even with the small 6 x 3.5 coil depth over 10 inches are possible with these settings.

Next tip: Run the F75 DD coil on the F70 !

Summary:

For $ 649 nothing from the competition comes close to that F70 package. Power is comparable to the F75, Teknetics T2, but the F75 has more features and the T2 the expanded iron range you may want.