3 kHz coils - anyone have depth comps?

[mojotrout]

Hey there X-terra users, I was wondering if I could get some opinions on the 3kHz coils out there. I have some areas that are not too trashy, but do have random gum foil, a nail or three, and other assorted iron droppings scattered around. The phase number reading on this soil is anywhere from 15-24. Ive been searching with the stock 9in./7.5 coil with some success but I think its time to take a look at either the 6in/3kHz Digger or the 15in/3 kHz coil. What Im wondering is how deep will either of these coils detect silver/copper coins in this type of environment/mineralization? Ive read that the Digger is at most 6 inches deep unless really wet soil, but does have the advantage of sifting around trash. Does the 15 incher go much deeper? And if so, how much deeper than the Digger or stock 9in./7.5 coil?

I realize everything is relative to the ground conditions so maybe if someone has experience with all of these coils they can say how much deeper one is over the other, rather than simply reporting absolute depth of each. Im likely going to get the Digger no matter what just because of its reported utility in congested sites, but if I will get several inches more depth in cleaner areas with the 15 incher, I might get both. If the difference is only an inch or two, I wont bother.The main areas Im detecting are not huge, so coverage would not be a factor for the larger 15 in coil, Im only concerned with depth and, to a lesser degree, separation.

What say you?

 

[Old Longhair]

It has been my experience that the 15" is a great coil, that does separate well, and runs deep. If the conditions are mild you'll need a shovel, 'cause your Lesche digger will take you all to day recover targets as deep as you'll find.

The biggest advantage to the various frequencies isn't so much how deep they go, but rather the response to target metals. If knocking out iron and still hearing high conductors like silver and copper is what you want, then often 3kHz is going to be the hot ticket. Wrought iron and foil can still be dug, but only if the foil is wadded/packed thick enough, or if the iron is on end or otherwise big enough to respond like a higher conductor, in which case most often the size of it gives it away. Around here, the soil varies greatly from very mild to pretty hot, but 3kHz works well for me as long as the Ground Phase numbers are above 15 or so with that coil on.

 

[mojotrout]

Great info Longhair. Yes, Ive been wanting to see how the LF coils respond to iron vs silver/copper as I do not have any experience using any coil lower than 7.5 kHz on any detector. From what Ive read on this site, the 3 kHz coils are the way to go if one is interested in coin hunting in AM mode.

 

[tbrom]

I have the digger coil and have limited use with it so I really can't judge it. I have not dug a coin deeper than 6" with it to this point. I do have a question about the am setting you spoke of. I have been using my digger in a disc pattern that has nothing notched out. Should I keep my detector In am or in a disc pattern with nothing notched out? I don't mean to hijack your thread. I also plan to get the 15" 3khz coil before summer.

 

[mojotrout]

Hi tbrom, no worries, hijack away! I actually had the same question a few weeks ago. Longhair pointed me to this thread for answers--


http://www.findmall.com/read.php?55,1992964,1994453#msg-1994453

If Im reading his explanation correctly, running in disc mode w/ nothing notched stabilizes the TID a bit. Maybe this helps on deep targets? Thats where my TID struggles most. Im running AM still and have not tried it yet so I really cant say much more than what I read from other folks.

 

[7centsworth]

I have a 9inch 3khz and really like it. It likes the coins. I haven't made depth comparisons. But it does make a sweet sound on coins.

 

[tbrom]

I had read some place about running in a disc pattern with nothing notched and have done so for months. I saw your post and wondered if there was a different approach with the digger. Thanks

 

[benzoflex]

I have retrieved coins at about 8" with the LF Digger coil.
Ground balance numbers here run about 45.
Its funny though how i can find an 1874 Injun at 4" and find a 1914 Wheat at 8"???
Happy New Year!!