F75 LTD GB Setting for Better Fringe Target Signals

I am working with a test garden fringe depth clad dime and actually believe I am getting a more consistent audio tone on the dime by setting the ground balance number at 3 to 4 units below where fast grab sets the detector. Most people recommend setting GB 3 to 4 units above the fast grab number. It seems to me that setting GB below the fast grab number is making the detector less sensitive to a positive response on ground minerals which in turn makes the dime signal less influenced by the surrounding ground. I am doing this testing in discriminate mode, bP process, 60 sens, 4 disc, 4 tones. I've only tried this a couple of times so I definitely haven't reached any conclusions on the validity of this yet. By the way, in pinpoint mode, the detector goes completely silent, when on the ground, until the coil is over the target. Any thoughts?

Interesting...I've always heard a few notches to the positive side too.

Maybe Tom or someone else technically knowledgeable could explain the reasoning for a better response with the -GB?

Try it with all of the tones.

LowBoy

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Setting slightly positive generally improves depth and most set ground balances are set up in this way...Might give Fisher a call and talk to a tech as they usually have little hints that don't show up in field tests or detector hype ads...

In most cases .. this is true; however, the TYPE of mineral(s) dictate which direction (slightly plus or minus) is more beneficial. This justifies the criticality of a test garden! I find that a more positive (numerically) Grnd Bal will give greater depth.... but slightly less ID accuracy.

Lawrenzo Wrote:
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> Try it with all of the tones.

Ok I'll do that Lawrenzo, but please explain why that is important.

wondering if it effects the other tones say the forth tone is a bit broken up what does tone 3,2,mono sound like.

LowBoy

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If you don’t dig it, then how are you going to know what you’re missing!
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Ok I just spent 30 minutes over my fringe depth clad dime. Let me start by saying that the signal improvement I am hearing by setting GB 4 displayed units below the fast grab GB is incremental. I certainly wouldn't classify this as a major breakthrough.

I do get a more consistent detection of the dime, however slight it may be. The fact is I am working in one location, under one set of soil conditions. In another location, even on my own property, the improvement might not be discernible. Also, I don't know that the improvement would be noticeable in an actual hunting situation where I don't already know the location of the target. For target checking, however, it would help. For any interested here are my conditions.

Soil - slightly moist clay, 69 fast grab GB, Fe3O4 .03 to .1

Target - new clad dime at exactly 8.5 inches deep, in the ground just a couple of days

Detector - F75 LTD, bP process, 60 sens, disc 4, 4 tones

Lawrenzo, I tried from 1 to 4 tones and didn't notice any improvement in signal quality over what I am seeing.

The ground cancellation has an affect on both the high conductive target range and the low conductive target range. It is easiest to observe on the low conductive side. Take a nickel as an air test object and check it's response as you lower the ground balance number toward 0. There will come a point where you will begin to loose performance to the nickel. You will probably start to notice it when you start getting below a ground number of 20. You will see a huge loss of performanc when you get to 0.

The same holds true on the high side as well only it isn't as noticable as the ground balance range is expanded on the ferrite end (for Fishers units anyway). But the closer the ground cancel number is to ferrite, the more noticable it will be. Since most folks ground isn't that close to the end of the ferite range it goes relatively unnoticed. Except by you, dgc, cause your playing with fringe depth targets in a test garden


HH
Mike

Mike, this is correct......and transitions to all brands of VLF units.