Max Gain Adjustment, ABCs, 123s?

[MartinL]

OK, you are setting up on a site to hunt. The advice is to adjust the gain until it gets chattery and then lowering the gain a notch or so.

Exactly what is used to benchmark the chattery condition?

Is chattery on ground sweeps?

Exactly what is chattery? Gibberish and beeps, bleeps and nonsense I figure. Some of that seems inherent to these things though.

This is never really a well explained procedure in metal detecting 101, it appears(to me) to be an understood term and an understood procedure of tuning for max gain. This may be so elementary to many here that is seems a stupid question, but if you don't ask a question, you never learn. Besides, others might wonder and be reluctant to ask.

Second, when you get that max gain setting, say you are working an area where you will drift toward power lines at some point. Is the max gain setting done twice? Is it done one time, in the EMI area so you cover all of the area with one max setting?

Maybe this will help others besides myself. Oh BTW, I'd never ask this question on that other board. I'd have been fried in oil. That's why I like this site.

Thanks,
Martin

[russellt]

i usually leave my rx about 10. and adjust down if needed.

[del]

:omg: fried in oil :shocked04: :huh: only if you were onion rings of bay scallops :smitten: :smitten: lol lol
even though i don't have a v3i the basics are pretty close ...
i will run my dfx up hot until it acts a little erratic ( maybe falsing , nulls and unexplained beeps here and there on some swings ) then back it down just enough to smooth it out . some areas like powerlines that give off alot of emi you might have to back it down even more to compensate , also i belive there is a frequency offset on your machine and that might help some too. i'm sure Jack or someone else with experience with that particular machine will give more info than me .

Dan

[MartinL]

I shouldn't have really mentioned the V3i in particular, just the generality of what to listen for, and where to make the tests(ground, air.) I presumed that it was just as you stated. My old 5900 would stutter in the threshold hum and I backed off the SB control. I haven't heard that with the V3, and it appears that I could run the V3i at 15 without radically destroying the tone pattern. I expect that the 10 concentric must be zooming in on lots more trash and such that the 6x10 works through. I dug a 10 signal with the big coil last bight and got nothing, yet the signal was still saying a VDI of 87-92, only one direction though. The 10 D2 seems to beep here and there at random from a gain of 4 all the way up to 15, but generally about the same either gain number. Hence I decided to ask where and how to totally do the procedure correct. I need to force the V3 to some gain that will make it noisy everywhere and not just at spots where one target appears to be cluttered with other junk. I think I'll switch on boost and come up from the bottom on gain until I get it to blare out some definite chatter.

Again, I am getting specific with these Whites machines as examples. I believe that I can get the gain properly backed down correctly once I understand where the breakdown really is. I put this thread in the general detecting forum cuz I felt it was a general item question. Maybe it should be moved. Thanks. martin

[coinnut]

Usually anytime your VDI numbers are flashing, it is time to back it off lol I do it a little differently. I go by the chatter and the numbers being stable, and then I up it just a little bit into the unstable range. This little bit of unstableness gives me a little more depth. So I back it down until it is stable and then up it a bit.

[MartinL]

I believe that I understand now. I do think that I will turn the boost on and click the gain up from 2, to 3....until I get a dramatic showing of unstable, just for a self show and tell. Thank you for the patience and the feedback. martin