F75 SE LTD - What confidence should I dig?

[BadM0nkey]

This is going to take some getting used to. I took it to the back yard today for a quick test run.

Default Process, 60 Sensitivity, 15 Discrimination. 11" DD stock coil. Fast-Grab ground-balanced.

Got a very reproducible "95" ping that read 10" deep. Pinpointed a few times to make sure it was right. Confidence was 2 bars. Dug down about a foot. Nothing from the ProPointer. Retested the open hole. Same "95" reading 8 - 10 inches deep. Dug another few inches. Nothing again.

With a 2 bar confidence should I have ignored the ping?

 

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[masterjedi]

It most likely is in the side of the hole (not correctly pinpointed)... Or its a small piece of aluminum,foil at surface level...

 

[crazy4coins]

With the short time I spent with my F75se (got ripped off by an eBay seller) one of the things that stood out to me was its love for micro targets. Few pieces if advice:

1. Don't pay much attention to the confidence bar. It's pretty much the same as a signal strength meter, and deep targets will not ring up very well on it. After a little practice, YOU will become the confidence meter.

2. Always scan the ground with a pinpointer before digging, regardless of the pinpoint depth. this will keep you from digging 10" holes looking for a piece of foil on the surface.

3. Use the detector's pinpoint function to center over the target. If you only get a good signal away from the center, chances are it's junk.

Hope this helps!

 

[Gaspipe]

I have never bothered to look at the confidence bar . I am a woods digger and I run mine hotter and with less discrimination than you are doing (95 sen and 10 discrim with 3 sounds) ; just my preference after 6 months of using it . I believe it takes quite a few hours to get the feel of these nice machines. As far as pinpointing as you describe it also takes some practice with the stock coil. Try the 5 inch coil to get better feel. Stay at this machine and you will grow to love it. Remember it goes deep so only dig repeatable signals that hold tone when moving around the target, if weak but repeatable dig it . Last week I dug a thin half reale on edge at 8 inches. To me that is sensitive but the signal was weak but repeatable . Go by sound and forget about the confidence bar.

 

[BadM0nkey]

Thanks everyone. I am new to this machine but not the hobby. I always pinpoint from 2 sides 90 degrees apart and every pp marked the same spot under the center of the coil. I ran my Garrett propointer all around and inside the hole but got zip. My hole was pretty big by the way. A good 9 inches around with little taper. The propointer will usually sound off a couple of inches from a coin or tab and a good 4 inches from a buried can. I'm confused but not deterred. I will swap out to the 5 inch coil tonight and try again tomorrow.

What I though interesting was the extremely narrow pp response area. It went fromquiet to shrieking to quiet over 3 inches side to side.

 

[crazy4coins]

If you want a larger pinpoint radius, raise the detector off of the ground and away from the target, engage the pp mode, and then sweep in towards the target.

 

[BadM0nkey]

I put the 5"DD coil on last night and I am looking forward to seeing what it does in the same spot. I am used to a 10" x 14" on a PI machine so this thing is really tiny from my perspective. I think my coffee cup may have a bigger diameter. Thanks for the advice.

 

[Charlie P. (NY)]

95 is above the range of coin readings and could be a magnetic rock ("hot rock"). You're probably over a large piece of iron or other metal.

Detectors aren't too bright and they assume everything is coin sized. So a coin at 8" has about the same conductivity in the coil's field as an engine block does at 36". But the F-75 does have that confidence meter that helps. Also check out the Fe2O3 scale. If that is up and the confidence is down it's probably iron.

 

[BadM0nkey]

At this point I'm guessing it is some big piece of metal down over a foot.

 

[jas415]

With that vdi and depth I think you are digging some sort of rusty iron. I dont think I have ever dug anything good with a VDI above 92-93.

 

[BadM0nkey]

Thanks. I have been too busy to get out back again but will test with the 5 inch DD

 

[BadM0nkey]

Thanks. I have been too busy to get out back again but will test with the 5 inch DD

Ok so I spent some time in my backyard with the 5" DD. Still really trashy but I was able to separate and dig targets. I'll try to hit a park or playground soon.

 

[Hookedondetecting]

The 5" is my favorite coil. That is all I used last Summer. Pin pointing with the 5" can tell you what the shape and size of the target is.
A couple of times I found a length of copper pipe. You could tell the target was longer than a coin.
Over the winter I picked up a 10x5 Fisher coil.
It has a forward and rear Hot spot. So I have to be careful I am PP on the right end.
On elongated coils I slide the coil to my feet listening for the tone to drop off.
Usually the target is at the tip.

 

[BadM0nkey]

I took the F75 LTD out to my closest tot lot which I had carefully swept a couple of weeks ago with an Ace 350. I use DE, 70 Sensitivity, 4 Desc., No Notches. It was like night and day compared to my extremely trashy yard. Clean signals, no noise. I pulled a bunch of copper and clad cents, foil, tabs, weird hardware and assorted rusty staples. Most targets were down around 4-6 inches. Considering I had just swept the area, the 350 missed all these things. I need a good 4 - 6 hours or so with it in a good area but I am starting to see the appeal.

 

[BadM0nkey]

I was doing some air tests in my office today with the F75 LTD and discovered that the majority of the indoor EMI was not my wireless router or computer, but the bunch of plug-in battery chargers spread around the room. Even without batteries in them, they produce a huge amount of EMI that the F75 LTD picks up on.

The other thing I learned is that, at least in air tests, the F75 LTD All Metal Motion Mode picks up most metal objects at twice the distance of the Desc mode.

 

[Charlie P. (NY)]

My original Fisher F-75 (first year they came out) was pointless to even turn on indoors. The EMI from everything just made it percolate constantly. The upgrade has MUCH more shielding and counter-measures to stabilize it.