Concentric versus double D coils.

[Coinseeker 78]

Under what circumstances would the concentric stock coil be best to use over the double D 8X11 double D coil. Thanks in advance.

 

[ElginTim]

I use an F70 and so far testing my 10" concentric leads me to believe it's best suited to totlot hunting. For the most part because of coverage and it can still get close to all the posts and spikes and do a good job.

I tried it out at my usual haunt, sidewalk/parkway tearups but I can't say I gained anything from it. Was hoping for better ID and maybe better depth than the 5" DD coil but I didn't realize that in any noticeable or measureable finds. The 11"DD is too much for that matrix, with scrambled goods all around and lots of trash, it's just not as capable as the smaller coil.

I tried the 10" in my "test garden" (the large schoolyard out back), found out I much prefer the 11"DD there. But it is good for totlot work, better coverage than the smaller coils, no noise from local sources (EMI chatter) and good ID on even the smallest targets. What I don't like the is changing the coil as often as I change sites during the "busy" season. Maybe I need a second, dedicated rig for that coil...

 

[TerraDigger]

If your plagued by alot of bottlecaps, reading as quarters, you may want to use the concentric. If your in a really trashy area, you may want to use the DD to get in between the trash more effectively than a concentric will.

 

[Elton]

n/t

 

[Dude]

Being a clad hunter I was looking for a coil with max coverage so I bought the 10" concentric 2 weeks ago for my F4 and have been out testing the 2 coils.

So far I haven't really seen a big difference between the 2 coils in mild soil. If I had to pick one coil over the other it would be the 11"DD. The 11"DD is a little better in most ever category.

Depth I would say the 10" might have a slight edge. I found a dime with the 10" concentric around 9" deep that's about the deepest I've found. (Using my Lesche as a measurement tool) That can be a hard call because you have to pass your coil over a deep one and know it.

Target separation the 11"DD was better.

Target response seemed better with the 11"DD. I always thought that was only a detector function but it was better with the 11"DD.

Ground coverage they where equal. I notice the 11"DD doesn't detects at the tips of the coil making it more like the size of a 10" concentric.

Target ID the 10" concentric was better, but only in the lower range. The 10" concentric gave steady more predictable numbers on a nickel, it also ID'd bottle caps better as scrap. With the 11"DD nickels bounced all over the nickel scale, which became a tale tale sign it was a nickel. Pull tabs locked on with no bounce which is a tale tale sign.

I didn't weigh them but the 11"DD seems to be a little heavier.

 

[mudpuppy]

Same here..especially what Dude said about nickles. I prefer the 11dd, of course, I have not really given the 10 a good workout, maybe only 6hrs total. It doesnt seem as balanced on my rig or work well with my sweep style as the 11, but then again, the 11 has thousands of hours on it. Changing to the 10 DID slow me down as I tried to learn its characteristics and consequently found some good stuff just out of curiosity, so if its the only coil a person has, they would do just fine.

 

[TerraDigger]

Personally, I like the concentric. Even though my soil is pretty mineralized. Current areas I am doing, max coin depth is 8" and the concentric is up to the job. The big plus of the concentric, to me, is the superior bottlecap discrimination.
The only downer to the 11" DD is its 'open spoke' design. It catches on everything. Kinda wears my arm out.
Dave J..... if you read this, would FTP consider making a smooth bottomed coil cover for all of their 11" DD coils. I think they would sell very well.