Question for Tom regarding gain settings and DD coils

I hate to preface this by stating the old saw about DD coils having a "blade shaped" detection pattern. Perhaps in the mid depth ranges they do but this question goes a bit further.

When I tried out the T2 a couple years ago for iron hunting my setup was strictly PF mode, disc 21-22 and senstivity in the 70's. With those settings the T2 needed a lot of overlap to pick out the tougher co-located targets. Moving the coil forward or back just an inch or two while sweeping would lose the target. Early on one of the old timers on another forum (he seldom posts anymore) saw this in a negative light but I did not. In my ground a sensitivity setting of 70 gave solid hits and ID's on wheats at a true 8" so I never felt the need to run it higher than that in iron.

Ok Tom here is the question, Does the higher sensitivity setting negate the need for using a lot of overlap or are the better results you claim due to being able to see deeper co-located targets? In other words, is the detector able to see "thru the noise" of high gain settings and make the old saying of high beams in fog a thing of the past?

Tom

I'm waiting for an intelligent answer too.

Tom,

The results are a paradox. The HIGHER the gain..... the better the see-thru. Yes, there may be a few remote/isolated scenarios where this is not true...... however, the bulk of the handicapped targets will report better with a higher gain setting. This is for the F70, F75, T2 and some of the other F-series units ..... but MUST be equipped with a elliptical DD coil. I think that I have reported this (and probably in greater detail) in previous posts.
First; There are targets that are so badly handicapped...... so closely co-located together............. that....... the only way to detect the good target may present a 'window-of-opportunity' of just a half-inch of fore-aft coil placement.... and maybe only a 20% 'window-of-opportunity' of body rotation whilst sweeping the target..... and maybe even with a very tight/narrow 'wiggle' between multiple bad targets.

And on the subject of overlap........ most people have the misconception that a DD coil EM footprint is a 'square' wiper-blade footprint. Not true. Just as with a concentric coil........ a DD coil detects to a lessor depth if the target is under the tip of the coil.... or under the heal of the coil. Best detection performance/depth capabilities....... is in the center of the coil.
What is interesting about .... specifically... the DD coil,,,,, is the fact that you may detect a multi-co-located target at it's best... with the coil placement requirement to be 'extra' forward..... or 'extra' aft (a deliberate overshoot). This is because; If the coil is dead-center over the good/desired target.... this may place the heal or toe of the coil TOO deep into a trash item.

Tom

So we should still overlap about half on each sweep?

That is where running with minimum iron disc comes in. The more iron you hear the more careful you have to be with overlapping. Tom made a very important point about signals that only allow a small degree of rotation before being lost, those should not be ignored.

Tom

So by that, where possible we should run the F75 at 0 discrimination.
Now I'm hoping to hunt a ball field/ park where I have found wheat pennies in the past, but it's full of foil wrappers. I thought about setting the discrimination to 21, which is the hot spot and running the sensitivity as high as possible. What's your thoughts?

everyone has their own individual preference. If I hit and older site like a one room school for instance and want to limit my digging I tend to use 3 tones for coin hunting. There is bound to be iron along with the normal trash (assuming it has not been hunted at low disc in the past). Three tones allows for better audible hits on things like co-located nickels vs 4 tones. Nickels can be plentiful in older areas that have been hunted in the past with higher disc settings so I'm always on the lookout for them at old sites. This is just my preference that works for me when I am not in a beep-dig mood. So take it for what it is. LOL

If the foil wrappers cause a lot of problems slowing you down you have to make the choice on the best way to handle it. I will admit that when I had the Coinstrike I would at times notch out foil since it tended to hit pretty hard on low conductors compared to what I had been using previously and could get a bit annoying.

Really there is no right or wrong way, its more personal preference and what suits your style.

Tom