F75 Limited depth readout off

[amcoins44]

I have had my F75 limited for about 2 months now and enjoy especially it's lightweight compared to my White's XLT. But it's really frustrating that the depth readout when pinpointing is routinely showing about 2 inches too deep. This for coin targets, using the stock 11" DD coil, and with pressing the coil flat to the ground on final pinpoint.

Does anyone have a suggestion as to why I would be seeing this? In the end, it'snot a big deal to me and the way I hunt (mainly parks and schools for coils and jewelry), but it's irritating.

Thanks, Andy

 

[RavRad]

Try reseating the coil plug and doing a factory reset.

 

[amcoins44]

I have done both, but will try again.

Thanks

 

[jim tn]

A good precise pin point helps some, but that is fairly characteristic of the F 75. At least with the 3 I have had over the last 12 or so years. I can pretty much tell the depth by the tone, but do check the depth reading on deep whispers.......and subtract about 2". HH jim tn

 

[WV62]

amcoins44, that is just the F75 some are better than others. I sent mine in for upgrade and ask if they could do something with the depth reading. I didn't get any comment from FT, but it was a little better when it was returned. If I need to know the depth I call my brother over with his F5 and he will nail it for me. I have found that I am off by a couple of inches with the 11" coil and more with other coils.

So I would suggest to think about it like this, if it says you have a coin at 6", the machine is saying it will not be any deeper than 6" and stop digging.

Not much else you can do.

Ron in WV

 

[jim tn]

The most accurate depth reading coil for me has been the 5" . Probably because it has a laser like sweet spot, thus getting a precise pin point. HH jim tn

 

[amcoins44]

Interesting that others have had the same problem. Seems like something that should be pretty straightforward for a metal detector. But I guess I don't know the electronics behind how the depth is calculated.

 

[jim tn]

Depth inaccuracy by various detectors is not all together un-common. Perhaps also why so many deep target recoveries get bandied about. HH jim tn

 

[REVIER]

In many posts over the years I have read this could be an issue on detectors built on this platform, the F75/F70/Patriot and T2...especially the F75.
2" off seems to be a common number mentioned, my F70 has always been dead on but I just consider myself lucky.
Some are better than others, doesn't seem to be much rhyme or reason to it...luck of the draw.
A couple inches is way better than several, my Nox is way off and I hope this update fixes it.
Just need to adapt.

 

[miserman]

Most of the F75's are this way. I always dig for the target at 2 inches shallower than the depth reading. This works well for me and by digging this way I don't scratch very many coins. Just do a depth reading while pinpointing and subtract 2 inches.
Good luck

 

[Mike Hillis]

The pinpoint depth reading discrepancies is kind of normal for DD coils, especially for flat objects like coins whose signal is generated off the faces of the coin. A perfectly flat coin will pinpoint pretty decent but once you start to introduce any angle to the horizontal plane the pinpoint will be off. The greater the angle, the greater the degree of error. You see the extreme results in fully perpendicular coins where you get a response a few inches to the left and right of the actual coin location in the middle.

A concentric coil will innately be more reliable with pinpoint depth readings but you still have to deal with face angles.

Of course last you have factor in what size coin was used to calibrate the pinpoint depth reading. I believe a quarter is used to calibrate depth readings. If that is true, then anything non-quarter in size is going to be off a little.

HH
Mike

 

[MarkCZ]

If your detuning while your pinpointing then that's one reason for it, after you pinpoint the target take something like a plastic poker chip
and mark it, raise the coil off the ground and go into pinpoint mode in the air, then while still in pinpoint mode lower the coil back down
onto the marked target and then read the depth.

Mark

 

[Rob in (Ca)]

My f75 depth readings with the stock 11 inch biaxle coil has never been accurate

On my teknetics G2+ with the stock 11 inch biaxle coil, I have spot on depth readings ?