Usually once set for a coil, the pot won't need re-calibrated every hunt after that unless you bump the pot or switch coils. But don't think it needs re-adjusted until the machine warms up about 5 or 6 minutes or so. I often find it'll be about 2 digits off until the machine and meter warm up.
Don't think of the adjustment pot on all Sovereign meters as a negative. Think of it as a positive. By calibrating the meter to the coil, you can be sure taht all targets on the scale should read identical from coil to coil, where as on other machines based on the coil being used some targets can read a bit off in some situations.
I have tried adjusting the meter with a coin in the air or in the ground and it makes no difference that I have ever saw in VDI. I try to adjust the meter towards the high end of 180 so it's more prone to do that easier on targets, just in case a borderline silver coin might not be able to get over the hump due to minerals or dry conditions or being word or on edge or something.
I have tested Ron's meter and the Digisearch Minelab meter on various targets from low to high condutors and nickels in between. All these targets read exactly the same in the test pool I used from meter to meter, so you can be confident any meter should read the same if calibrated properly I would think. Also, Ron's meter will go -506 (negative 505 or 506....I always forget) just like the Digisearch meter when the machine resets.
I calibrate a meter in the field by thumping the coil on the ground to get the machine to reset, so I don't have to throw a coin down and then pick it back up after calibrating. If the meter is set to -505 or -506 (forget which off hand at the moment) it will go 180 on a clad dime or quarter or silver coins. Sometimes copper pennies like wheats read 180 for me too but many don't for me, and will linger in the 178 # range or so, and there are various wheats or indians that will also read lower down the scale too in several places.
PS- My Digisearch meter is getting a dead spot in the tuning pot which makes it tricky tune tune and seems always out of calibration from hunt to hunt and requires re-adjusting. Sooner or later I'll take it apart and clean that pot with some non-residue electrical contact cleaner. Also, there is a second rough calibration adjustment pot in there, so even if I can't fix the dead spot I can turn that other pot a tiny bit and then the external one should ride on a different contact point avoiding the dead spot. Been meaning to do either or both these things if the cleaning don't help
I baby Ron's meter as my quality back up unit, since my Digisearch has been used and abused in the woods or a drizzle in the past. I figure so long as I keep Ron's reserved on for nice days in open areas on certain days when the mood strikes me, I'll always have it as a reliable backup for when the Digisearch finally bites the dust.
But, on the other hand, I'm planning on picking up a used Sovereign control box for my water rig some day, since I don't need any coils or shafts for that, and if I do I can see myself loaning on that second Sovereign with Ron's meter on it to expose a few season detectorists I know to the Sovereign "drug" of addiction, because while they have owned just about it all over the years, they ain't tried this very unique beast yet. Yes, I've got sinister motivations for doing this. Once they get a taste I think they'll be wanting more and more.
HH Jim
