Hi, Steven,
I'm sure that you will get a number of suggestions from both users and field testers as to your depth problem with the 70, but here is what I would do:
Since you already have the 50, you are in an excellent position to do comparisons with regard to depth. So I would suggest resetting the 70 to factory presets. Then take your wife with you to the location where you were finding targets at 8" to 10". Have her locate a good target with her 50 at that depth (say 3+ arrows) and mark it, then go over the target with your 70 & see if you can read it. Do this on a number of targets & post your results.
Also, when you did your depth test with the quarter buried at 6", did you check to see if you could read it with the 50?
It's often very easy to wonder about a detector's depth capabilities when you aren't finding anything deep. I find myself questioning my Explorer sometimes when I'm not finding anything except shallow coins when the reality is that I'm just not passing the coil over a deep target (or the target is too deep to sound off). Not saying that this is happening to you, but until we can determine whether the 70 is missing readable targets or the deep targets just aren't there it is difficult to know whether a problem exists or not.
Keep me posted.
Bill (S. CA)
