Joe there's a lot to digest here but I hope some of this helps.
1 - Three inches is pitiful depth the Explorer will go much deeper. Our ground is dry right now but we are still digging indian cents 6-7 inches deep. I dug an 1873 close to 9 inches deep with the stock coil last weekend and the ground was bone dry all the way down. Not the best signal but it was definately diggable. Step one, make sure there is nothing wrong with the machine by doing some air tests with various sized coins and report your findings back to the forum. The detection field extends several feet so don't place the coins on the ground, its best to aim the coil at the horizon to eliminate the ground matrix during air tests and wave the coins under the coil. The Explorer does not air test that well because it uses to ground matrix to improve depth but you should still be able to get 5-7 inches on most coins in an air test. When the threshold disappears the machine is over a target you have discriminated out, iron/trash etc. That is normal. Don't worry about the ground balance, its automated and adjusts itself as you go. Its also quite good at doing what it does. What you should do is set your iron mask to -16 e.g. nothing discriminated out e.g. all metal including iron. Hunt in smartfind with your discrimination pattern and when you get wondering why the threshold has vanished on you, switch to iron mask, with nothing discriminated out you will be able to hear all the trash targets. ALSO if you are running a LOT of discrimination it may be masking a machine that is actually setup unstable. Underground power lines for example will make the Explorer false like crazy but with a ton of discrimination it doesn't sound bad because most of the falsing is hitting in the discriminated area. So again switch to your iron mask mode with iron mask at -16 to tune your machine sensitivity, gain, etc. If she's running stable your good to go.
To improve depth the first and best thing you can do is SLOW down your sweep speed. The field Ed and I dug all these recent coins out of is infested with modern trash and 150 years worth of rusty nails, big ugly ones. I made 2-3 medium speed passes over this field and found nothing, then I went into slow to a crawl mode and the deep coins starting popping out all over the place. Next I like Deep ON Fast OFF with my gain at 7. Its easier to hear the deep targets verses the shallow ones that way. Deep targets 6+ inches sound larger as you sweep across them, say 4-6 across versus shallow targets 2-5 inches which sound about 2-3 inches wide. Deeper targets also sound more flutey like multiple notes on a flute or an old style bycycle bell. The deeper the coin, the more fluty it gets. Surface clad and trash can polute a large area around the target, either dig it out of the way to move on. Once you get your ear trained for that deep coin sound, keep an ear peeled for the classic double signal. You'll make a sweep, it will sound almost like a single target but you hear that deep coin type signal mixed in. You check again and find a shallow target nearby. Shallow targets don't give off deep coin signals so there are VERY good odds there is a deep coin hiding near the shallow target. I dig the shallow target out of the way and probably hit a deep coin 80% of the time. Step one of course, learn what deep coins sound like. Now if you turn Fast ON...all bets are off, it makes deep coins sound more like shallow ones e.g. I find it tougher to hunt deep coins that way. Reduce the amount of discrimination you are running to improve depth. Try this, edit your smartfind screen to black out the entire bottom 1/3rd of the screen. That will get rid of 80% of the trash targets leaving mostly coins and iron. Now set your tones to Ferrous, that will make iron sound low, coins high. Now go dig some coins. Once you learn what deep coins sound like you can gradually open up the bottom of the screen. About the only thing I discriminate out these days is rusty bottle caps, the rest of my screen is wide open. While you are learning when you think you found a deep coin, switch to your iron mask screen set to -16 and sweep the target again from a few angles. Thats good practice, with nothing discriminated out you will notice how much better the signal can be on a good target. Plus its easier to pinpoint in iron mask at -16. Finally, THE best depth tip anyone ever gave me was to go out and dig every non-iron signal at a given depth or deeper. Say 6+ inches. If you are finding modern trash at 6, dig targets at 8+. Using the depth meter and ignoring the target ID did wonders for me. I tell you coins can and do ID WAY off the textbook mark when they get deep. They can sound pretty crappy also. If you are waiting for a textbook type ID on a deep coin you may be in for a long wait. The machine is accurate in our ground to about 5 inches, often its good to 6 inches, but if you are talking an indian head at 8+ inches I have seen them ID all over the screen from iron high left to half way down the screen right. What gets our attention around here is that coin like behavior, a wider signal, fluty, couple that with the right depth and we dig even if the tones and ID are off.
2 - Call Kellyco, they should last longer than 3 hours in my book but its their product.
3 - Most of my settings are above, I adjust my sens for a reasonably stable operation not squeaky clean stable. I like a minimum sens of 24 and will go up to 28 conditions permitting.
4 - Hey digital is fine for shallow coins but if you want to troll for deep old coins put all thoughts of using digital mode out of your mind. The ID varies too much on deep coins for digital mode, the numbers will bounce all over the place unless your soil is mineral and trash free. Take deeper nickels for example, those damn things will bounce left and right about an inch across the screen. Just watch the cursor instead, its easier to learn the bounce patterns than looking at a bunch of numbers changing. The cursor may be bouncing left and right, even up and down but silver bounces different than indian heads, and indian heads different than say wheats. Nails trying to false have their own bounce pattern also. Ed is the nickel king around here but I look for the right height vertically, if its in the nickel zone height wise on the screen and bouncing left and right, plus sounds a bit larger/wider like a coin I'll dig it. Theres lots of beaver tales right in the nickel zone but they sound flatter and shorter as you sweep across them. Tech note, if you have rusty bottle caps disc'd out as I often do, if I think I'm onto a nickel I switch to iron mask -16 because nickels can bounce over into the rusty bottle cap zone whey they get corroded.
And before you get cussing the digital mode as useless like I did...understand that if you pass the other top brand detector over some of these deep coins the Explorer finds, while the signal may not be the best on the Explorer the other brand detector gets no signal at all or at best ID's the coin as iron. If you want to go deep you have to rely more on how the target sounds and less on the screen target ID.
Charles
