How Deep Will 705 Go

[moose57]

Hello everyone can anybody tell me how deep the 705 with the 9in.coil 7.5khz.or the 9in.3khz.coil go..

 

[TomB]

Moose...I don't think anyone can answer your question. There are a number of factors that will determine the depth of any detector. Electronics, ground condition and type of soil, just to name a few. It also depends on what you are hunting for. The only way you will know is by keeping a record of your finds and comparing one to another. HH TomB

 

[Terra1959]

Hi Moose

Tom is right there are so many variables
As he stated - It depends how you set up the detector with Sens, GB , the soil conditions (type, moisture, mineralisation etc) maybe also how skilled the user is.
But to try and provide you with an answer.....on an average coin sized object it is my estimate that one could expect 8-9 " with those coils
(deeper on really large metal objects)

T59

 

[tabman]

Has anyone done an air test using the 9 inch 7.5khz coil and the 9 inch 3khz coil on various coins.

I'd like to know how those two coils stacked up against one another on coins.

I keep reading that the 3khz is deeper on silver in the sales ads, but I haven't seen any actual data.

Is it mostly hype? Is it worth the money to get the 3khz coil? How much deeper is it on Silver?

 

[Digger]

I've compared all three 9-inch concentric coils, side by side. And frankly, I don't see any difference in depth of detection on US coins. The "rules of thumb" that we hear so much about are bigger coils detect deeper than smaller coils...... DD coils separate targets better than concentric coils, concentric coils provide a more accurate TID than DD coils, lower frequeny coils are "better" for higher conductive targets, higher frequency coils are better for lower conductive targets, lower frequency coils detect larger objects deeper than higher frequency coils and higher frequency coils are better at detecting small objects than lower frequency coils. I think we can agree that it makes sense that a larger coil will detect deeper than a smaller coil. And from a technical standpoint, a DD coil will separate targets better than a comparibly sized concentric. But I believe all three frequency coils for the X-TERRA will each detect gold, silver and copper just fine. Based on my observations, I find the HF is more sensitive to smaller targets as I need to turn the sensitivity down a couple clicks when I use it in trashy areas. And I like the audio tone provided by deep iron (multiple tone, minimal discrimination) on the 3 kHz coil. But as far as depth is concerned, if you are able to properly ground balance your concentric coil with a ground phase number of 28 or larger, I would think you should be digging quarters at 8+ inches with any of the three frequencies. As to the 3 kHz coil being good on silver...... in wide open spaces where target separation is not an issue, the 3 kHz coil is a silver killer! It may not be any deeper. But the audio response is much more distinct (on small silver US coins) than it is with the other two frequencies. In addition, when I hunt in multiple tone with minimal discrimination, it gives me a very distinct set of harmonics on deeply buried iron.

With that said, the silver US 3-cent piece is the smallest silver US coin ever minted at just 14mm in diameter. I found mine in a trashy farm yard, using the 6 inch DD coil. I didn't chose the 18.75 kHz for it's frequency. As I said, I prefer the 3 kHz on silver. But in this site, target separation was my primary concern. And I am convinced I would not have found it with any other X-TERRA coil. JMHO HH Randy

[attachment 191656 finished3centsilver.jpg]

 

[goldseeker4000]

Like everyone said it is hard to say but I can tell you that with the 5x10 DD High frqnz coil I found a lead bullet at 12 inches deep while prospecting for gold and with the same coil I found a 1946 wheat penny at 9-10 inches deep. I was told by one of the guys at minelab in Australia , depending on coil and ground circumstances the 705 can reach 18" deep. I will have to wait and see if I ever acchieve this depth on a good target.

 

[moose57]

Thank you very much everone that answered my ? on how deep will the xterra 705 go.I live in ohio the ground here is around 63 minerlizeation I guess that means the minerals are moderate
I had seen on the mlotv that if a person lives in this type of ground that a DD coil would not be effective is this true.Would it help me to get a 10dd 7.5khz.coil and if I did would this help on
depth.

 

[moose57]

Like everyone said it is hard to say but I can tell you that with the 5x10 DD High frqnz coil I found a lead bullet at 12 inches deep while prospecting for gold and with the same coil I found a 1946 wheat penny at 9-10 inches deep. I was told by one of the guys at minelab in Australia , depending on coil and ground circumstances the 705 can reach 18" deep. I will have to wait and see if I ever acchieve this depth on a good target.

 

[Mtnmn]

I've never found a coin over 6 1/2" in my ground with the XT-70, no matter what coil was being used and I've heard from others around the country who also couldn't get anymore depth than that either with their XT-70's. Not everyone gets 8 or 9" on coins with their XT's.... How I wish we ALL could!

 

[Digger]

Part of the logic behind the design of the DD coil was to help combat the ill effects caused by excessive mineralization. (poor depth, irratic operation, unstable TID etc) If you are able to properly ground balance your 705 with ground phase numbers in the 60's, you don't have high levels of mineralization. But that doesn't mean a DD coil won't be effective. The DD coils separate targets better than concentrics, due to the design characteristics. However, in moderately mineralized soil such as you stated, I believe you will get more accurate TID readings with the concentrics. In addition, in those soil conditions, a concentric coil will hunt deeper than a comparibly sized DD coil. Unfortunately, we can't make that comparison with the X-TERRA as the larger concentrics are 9-inch coils and the large DD coils are 10.5 inches. So with that additional 1.5-inch diameter, you could likely hunt deeper with the large DD. Here where I live, I can't see much (if any difference). Regardless, you won't be hurting yourself for depth and you will separate targets better than with the 9-inch concentric. JMHO HH Randy

 

[digmeahole]

Has anyone done an air test using the 9 inch 7.5khz coil and the 9 inch 3khz coil on various coins.

I'd like to know how those two coils stacked up against one another on coins.

I keep reading that the 3khz is deeper on silver in the sales ads, but I haven't seen any actual data.

Is it mostly hype? Is it worth the money to get the 3khz coil? How much deeper is it on Silver?

http://www.findmall.com/read.php?55,1427094,page=1 or http://www.youtube.com/watch?v=iE9hTKyu79s

I got a 18" hit on the DD coil with a thin metal saddle that separates a rug from hard wood floor.....

 

[SeniorSeeker]

Can You Speak Chinese? lol