Thought I'd pass this along.This came from another web site but I trust the person who said it.
The Cortes is very easy to use. Set your disc just below nickel, and crank the sens all the way up. Good targets are strong and repeatable but there are some things that might help you.
Visual ID, in general, is non-reliable and by that I mean, when you get multiple targets under the coil, what you see on the screen will necessarily indicate whats in the ground. The Cortes is right on with depth and ID on clean, un-masked targets, but with multiple targets you have to be aware of what the machine is telling you. Try this test: tape a nickel and dime together and pass them under the coil with the nickel side up. See what the machine reads. Surprised? Now turn it over and face the dime towards the coil, and see what it reads. Interesting, huh? You need to realize the machine is looking at conductivity of targets so what you see on the screen can sometimes be totally different than whats in the ground.
But here is where your previous experience with the T and V will come in very handy: listen to your tagetst first, if they "sound" good, ie srong and repeatable, then glance at the coil to see whats its reading but dig the target based on the sound. If it sounds good, like you are used to on your T and V, dig it!
Gold rings can read up nearly anywhere but one tip that may help is, they area always strong and repeatable, the ID numbers and bar graph icons dont change much on each pass of the coil. Pull tabs and pop tops often jump around due to the odd shape of the targets and depending on how you coil is passing over them. Alter your stance as you sweep "pop top" range targets, sweep them from various angles and watch the ID numbers. If they dont jump around a lot, it could be a ring.
One other thing the Cortes is very good at and that is ID'ing iron. Large iron targets fool most machines, and so too with Cortes. They will sound and visually ID high like a coin. The ID numbers will be 95 and the coin icon will light, but there is one real significant thing that happens on large iron targets like this, and that is there will be a slight "sliver" on the iron bar graph. You have to remember to glance at that end of the screen because the coin bar graph is at the opposite end, but when you have a stong coin reading and see a sliver on the iron bar graph, its a chunk of iron. Dig enough of these to convince yourself and then you will be able to pass them by.
Once you master all that, there is another thing that I have seen occur on really deep targets, and this too is probably true of many machines. When you are scanning a target that is at the extreme limit of the machines capability, some times there is just not enough "oomph", not enough data for the machine to accurately read. On one pass you may see a breif "coin" signal but on the next it reads "iron". If you see that quick coin flash, stop and scrutinize this target. One thing you can do is to switch to the all metal mode. This will give you a tiny bit more depth, and maybe just enought to accurately get a reading on the target. The other thing you can do is to scrape about an inch of soil away (site permitting), which allows you to get the coil just a bit closer to the target. One of these things may allow the Cortes just enough signal strength to give you a better reading.
