I hope I'm not making a big deal out of nothing, but it is sounding like a bum coil. I just now tried this: Powerup, no changes to default settings. Merely waving my open hand over the coil's center makes it sound and ID about 51. Tap the side of the coil with flat of hand, or shaft anywhere with heel of hand makes a beep or two and ID of around 27.
In the process of elimination, I don't own a cell phone or wear a watch, rings or any jewelery. Machine's in the open, upsidedown, or otherwise held with coil away from any metal, such as my glasses, belt buckle or shoe eyelets, keys, etc. Cable's well wrapped and away from the coil. Machine's screws all tight. Shirt sleeve pulled up to expose bare arm. Not a newbie, detected 25 years, currently own 9 detectors, three have only manual GB. Just getting the simple or obvious explanations out of the way.
The default disc is 10, that did still beep a lot at my site. Most of the spurious ID's are in the 30's, so setting disc there might work, as the one larger "$20" nug I still have here reads 49 fairly often.
So I think we can deal with the site's conditions with more practice. Every other machine I own has worked there no problems, other than a lot of trash, but no severe falsing or gb issues.
The question to me now is whether anyone else is seeing handwave or bump beeps. Any machine that exhibits bad hand capacitance will also react badly in wet conditions, changing soil elevations and content and this may help explain my difficulties ground balancing and the many, many false tones.
If I can cure that, it will probably help at my site.
-Ed