X-terra round DD 18.75kHz or 7.5 kHz

[Reddog777]

I want to purchase a round DD coil for my X-terra 705 for better depth. Is the 18.75khz better than the 7.5khz. Any experience users?

 

[Mtnmn]

In my soil I only gained about an inch of extra depth by going to the 10.5" DD MF coil. Was "very" pleased with the depth of the 6" DD HF coil. If the 10.5" DD coil gave me as much depth for its size as the 6" DD coil does, I'd be in hog heaven...

 

[Clad2Hunt]

Go for the 10.5DD 7.5 if looking for coins. I had the HF coils in 6" and doesnt touch the depth of the 10.5 though it does have its place in trashy areas. I sold my 6"HF and got a 6" Concentric which is deeper. I went over a place yesterday with 10.5 that I had hunted with 6DD and 9" stock and both missed the finds I am posting next. I also used a 19K 11"dd coil with GBSE and it missed these deeper coins. For deeper silver 10.5MF all the way.

 

[Reddog777]

How deep was the coin?

 

[Mtnmn]

Clad2hunt is totally correct in his analysis of which DD coil should give you the most depth on coins, but I'm also guessing his soil is only moderately mineralized. In my own case using my particular XT-70, I have achieved much better results "for it's size" using the 6" DD HF coil than with the 10.5" DD MF coil. So much so that I'm seriously considering looking for someone to trade it even up for a 10.5" DD HF coil and hopefully achieve the kind of depth I should be getting with a 10.5" DD coil.

 

[Digger]

My soil is moderately mineralized, with an average ground phase setting of +/- 40. I do not determine much (if any) difference in depth between those two coils. The primary difference I noted is that I had to lower the sensitivity of the HF version to keep it from chattering. I can run the MF at 29 and had to lower the HF to 25-26 to operate with the same stability. Frankly, in my soil, I can get better depth (and a more accurate TID) with the 9-inch concentrics than the 10-inch DD's. JMHO HH Randy

 

[Mtnmn]

Apparently from the above replies, the only way you are going to know for sure which coil is going to work the best for your particular soil and detector, is to just buy one and try it out. An expensive proposition for sure unless you know of someone who has extra XT coils to try out. Have noticed that when using the 6" DD coil, it seemed to be bothered less by EMI than the 10.5" DD coil, but believe that is normal due to its smaller size. Really do like the 10.5" DD coil for how much more of an area you can cover with it.

 

[David]

As a good tool, also get the 9" LF (3 kHz) Concentric coil for silver-copper coin hunting, better more accurate TID than DD's, and good Iron IDing by sound-tone.

 

[Smithfire]

David, does the 3Khz coil pick up the smaller silver coins at depth?......Just wondered if it would pick up the smaller silver hammered coins we get here in the UK. How small is the smallest US silver coin?

Many Thanks

 

[mapper65]

Apparently from the above replies, the only way you are going to know for sure which coil is going to work the best for your particular soil and detector,.

I agree with Mtnmn. As drastic as that sounds, that's what I did. Looking back on it nearly a year later, had I gone with people's suggestions I believe that would have made the wrong choice. Yes, it's not the most cost effective way of doing things but I've found that the HF coils work much better for me than the MF coils based on the soil in my area. I will occasionally put a MF coil on from time to time but I bought the HF 6" & 10'5" DD along with the 6' concentric and 10.5" DD MF. I have given them all a chance and my deepest and best finds have all been with the HF coils. You may find just the opposite in your area.

Being that everything pointed to the MF coils being best suited for my area for the longest time I would start with the MF coils and when I felt I had everything covered I would switch to the HF coils. Nearly every time, I would find a decent number additional coins with the HF coils even after I thought I had cleaned the place out with MF coils.

I now start with the HF coils and then switch to MF coils. I can't think of a time when I found a notable number of coils with the MF after first searching with the HF coils.

Just my experience.

 

[Digger]

I'm not David, but the smallest silver coin ever minted was the US silver 3-cent piece, measuring 14mm in diameter. It was only minted from 1851 - 1873. Those minted in 1851, 1852 and 1853 weighed in at .80 grams. And they were 75% silver and 25% copper. [attachment 189223 finished3centsilver.jpg] Those minted from 1854 to 1873 were 90% silver and 10% copper. They were still 14mm in diameter, but weighed only .75 grams.
If you do a search of this forum for articles related to the 3 kHz coil, you'll find a bunch of them. I know I've probably written 50 of them myself. HH Randy

 

[Smithfire]

I'll do that Digger. thanks for the coin info.

 

[Reddog777]

Thanks everybody for all the advice and comments. I ordered the 10.5 DD 7.5 kHz round coil from Richard@Backwoodsdetector today ( a good person to deal with) and it should be here Wednesday. I'll give it a try and post my results

 

[Reddog777]

Okay, I recieved my 10.5 round DD 7.5kHz coil yesterday. I gave it a trail the same evening and I did find coins that I previous searched with other detectors. Whenever I power up, it is very noisy and the display is erractic. Is this normal?