Question about the 705 in iron ridden ghost-townsy sites

[Tom_in_CA]

For iron/nail ridden ghost townsy sites, where the objective is to "see through" (minimize masking) of rusty nails: What is the best coil for this ? The HF, MF, or LF coils ?

So for example: if you laid a rusty nail right over the top of a penny, the signal of the penny is now degraded, if not totally masked. But certain setups (the old Compass 77b for instance, and various 2-filter tesoros, etc...) can get a compromise signal where you can still tell there's a conductive target there (albeit TID not going to be "penny/dime" anymore).

So of the different coil options for the 705, and assuming the user has his iron disc down as low as possible . Or disc. totally off, and using only the tone ID's to discern between the iron low grunts versus something conductive trying to peak through.

thanx!

 

[argyle1]

A lot of us run the XTerra's in all metal multi-tone for that exact type senario Tom. No disc used so the full tonal changes can be heard.
Out of the three freq's (even though there is not a great noticable difference between the three frequencies of the xterra coils) I'm always drawn back to the 7.5kHz due to it's slightly truer Tonal and VID response, and while I've used DD coils for 30 years I find the Concentric coils better in nearly all applications on the XT's.

The 6"concentric 7.5kHz has a distinct advantage over the DD's in nail infested spots due to the nice little fat inner ring. Deep and hot little coil. It can see more of the coin and less of a medium/large nail (air test separation I know very little about, in-ground reaction/separation I know well) and gives nicer tonal pitch changes when flicking the coil in a tilted arc than the DD's.
Out of three units I find the 305 and 7.5kHz Concentric combo better in that nail/iron over coin situation than even the 705 with the beaut 3kHz Digger coil (which excel's at bottle cap/twist top ID'ing)

I find the larger DD's and Concentric's in all frequencies suck at nail/coin separation when targets are co-joined or above - below each other in the dirt, especially when a old nails separated halo comes into play.

 

[Tom_in_CA]

thanx for taking a stab at my question argyle1 ! In regards to the 6" MF coil favor you have, it seems that the reason for said-favor, is pointing to an aspect of separation. Because yes: the "cone-shape" penetration (where the deepest point of the detection scope is a "dot" rather than a "line", does indeed seem to point to an observation of target separation. I can see that as "given", since that's the age-old purpose of smaller coils TO BEGIN WITH: to see in and around targets better.

*However*, this is not addressing the part about seeing THROUGH (aka averaging). It seems to be only addressing the seeing APART (aka separation). It seems, from your post, that you're saying that there's not a lot of difference, in that department, between the LF, MF, or HF. Right?

Because I would have thought that the HF (meant for nuggets and teeennnssy low conductor things), would be the best choice for said-task. Because the HF has the odd side-effect of seeing through iron better, in the first place (albeit with the other drawbacks that HF has, less able for depth and high conductors, etc....). Example: Yesteryears High Frequency all-metal TR's (like the Compass 77b), were excellent in seeing through nails. This was due to their very high frequency. Naturally, their benefits ended there (in all other ways they were a dinasour).

So I just assumed that the HF coil would therefore be the best frequency on the XT's, for seeing through iron.

I watched a local fellow, with a 505 , using the 6" HF coil, that was KICKING OUR B*TTS at 3 to 1 ratio, on targets in an iron-riddled zone. We were using machines like Deus, and 3030 with small coil, etc... And this is a site that's been gone over with everything from 6000s, to CZ6's, to Tesoro 2 filters (in attempts to see through iron), to 77b, to explorers, etc.. etc.... Lots of reales, seateds , and buttons came out of this old stage stop area. But as time went on, all the "easy" stuff got picked out. Especially on the fringes where there was nothing to stop each signal from being an easy gimmee. So eventually, the only targets that remained were those in one particular area (about the size of a half basketball court) that was especially iron-ridden. Eg.: each hole would have a few nails pop out, along-side whatever it was you were trying to dig. Thus this has become the perfect test zone of a machine's ability in iron. And I was quite surprised to see this 505 come along and spank us 3 to 1. Doh!

So was wondering if it was merely a function of the HF coil, or if the XT itself is simply a "better mousetrap", to begin with.

thanx!

 

[7centsworth]

I have only used the mf 6inch cool and I really like it. It is one of my favorites for coin hunting.

 

[pulltaber]

I have to agree with argyle1 the small concentric will do the best in nails. I have tired Monte's nail board test on my 705 with a 6 inch Digger LF, a 6 inch HF they both failed the test. the 6 inch concentric did better but not as good as my old Tesoro with a small concentric .
Don't get me wrong I like my my Minelab most of the time but not in heavy nails sorry but no matter how slow I go or what setting I still miss a lot,that are easy pickings for my old T

 

[Crash67]

I am running the 9 inch 3 KHZ concentric and on Sunday I was pulling dimes and pennies out of plugs and holes with nails in them

 

[Mark in S.E. IA]

pulltaber, try the Monte nail board test using the X705 in AM and with only two tones and see how it does. When I'm in a heavy iron patch I like to use AM with 2 tones. It works pretty good if you do not have a lot of other trash in that of area, just iron and coins with very lil trash. I also like to hit area's like that when the ground is super dry. You just do not pick up the iron as much as you do when the ground is moist.

 

[argyle1]

thanx for taking a stab at my question argyle1 ! In regards to the 6" MF coil favor you have, it seems that the reason for said-favor, is pointing to an aspect of separation. Because yes: the "cone-shape" penetration (where the deepest point of the detection scope is a "dot" rather than a "line", does indeed seem to point to an observation of target separation. I can see that as "given", since that's the age-old purpose of smaller coils TO BEGIN WITH: to see in and around targets better.

*However*, this is not addressing the part about seeing THROUGH (aka averaging). It seems to be only addressing the seeing APART (aka separation). It seems, from your post, that you're saying that there's not a lot of difference, in that department, between the LF, MF, or HF. Right?

Because I would have thought that the HF (meant for nuggets and teeennnssy low conductor things), would be the best choice for said-task. Because the HF has the odd side-effect of seeing through iron better, in the first place (albeit with the other drawbacks that HF has, less able for depth and high conductors, etc....). Example: Yesteryears High Frequency all-metal TR's (like the Compass 77b), were excellent in seeing through nails. This was due to their very high frequency. Naturally, their benefits ended there (in all other ways they were a dinasour).



So I just assumed that the HF coil would therefore be the best frequency on the XT's, for seeing through iron.

I watched a local fellow, with a 505 , using the 6" HF coil, that was KICKING OUR B*TTS at 3 to 1 ratio, on targets in an iron-riddled zone. We were using machines like Deus, and 3030 with small coil, etc... And this is a site that's been gone over with everything from 6000s, to CZ6's, to Tesoro 2 filters (in attempts to see through iron), to 77b, to explorers, etc.. etc.... Lots of reales, seateds , and buttons came out of this old stage stop area. But as time went on, all the "easy" stuff got picked out. Especially on the fringes where there was nothing to stop each signal from being an easy gimmee. So eventually, the only targets that remained were those in one particular area (about the size of a half basketball court) that was especially iron-ridden. Eg.: each hole would have a few nails pop out, along-side whatever it was you were trying to dig. Thus this has become the perfect test zone of a machine's ability in iron. And I was quite surprised to see this 505 come along and spank us 3 to 1. Doh!

So was wondering if it was merely a function of the HF coil, or if the XT itself is simply a "better mousetrap", to begin with.

thanx!

You think I was merely "taking a stab" at your question Tom?

Target Separation, Seeing Through, Seeing Apart, Averaging, .... Same thing Tom.
If you spent as much time detecting with an XTerra as your Local Fellow that 3 to 1 you does, you may come to some real world conclusions that don't include a whole lot of theoretical nonsense.

The XTerra's were made for the 7.5kHz frequency and behave both Tonal and Visually at this freq with the best clarity. The 18.75kHz and 3kHz were an afterthought. The 7.5 is True, the other two are false 'digital equivalents' of their said frequencies and are only acting the part, albeit quite well.

You wanted to know the best frequency on the XTerra for hitting/judging coinage among rusty nails, the better Tonal changes for discerning rusty nail grunts from conductive targets Tom.... you got it ....Plus the best size coil to use in that freq and the pick of the 3 units (the 305 over the 705 due to the ability to run higher sensitivity with much clearer tonal clarity when iron and coinage are in the mix) thrown in as a freebies.

 

[Tom_in_CA]

Mark, crash, & pulltaber, thanx for taking a stab at my question.

For starters: Crash: no doubt, ANY machine will experience occasionally seeing a nail come out of a hole, during a retrieval. But that could merely mean one or two were *close*. Not necessarily *on top of* the target.

Ok, Mark & pulltaber: Interesting that you're saying you've specifically tried this in the famous "nail board test", and found that the 6" MF was better than the 6" HF, in that test. Hmmm, because I'd have guessed/assumed that HF, by it's very inherent traits, is better as seeing through (aka "averaging") rusty iron nails, than Low or Mid-frequencies.

For example: The old compass 77b (which could see through up to nearly 3 nails to hear a coin) was a very high frequency. So I'd have assumed therefore, that the HF option of the XT would be best for this task. Granted: There's other downsides to HF, like less depth, less ability in minerals, less depth on high conductors, etc.... But for the task of averaging with iron, I'd have thought HF was going to be the better in this test.

The only MF coil I have here for my 705, is the 9". And it's not doing as well as the 6" HF I have, in staged tests. But I realize this isn't an "apples to apples" test. Since, of course: The 9" coil is much bigger, hence "seeing more ground".

Hmmmmm

 

[Mark in S.E. IA]

Tom, I never said that I did the Monte nail board test, I just asked pulltaber to do it and see what happens. I never do air test, they are a waste of my time, lol. Also I have never used a 6" MF or HF coil. The only coil I ever use on the X505 is the 10.5 MF DD coil because the soil in my area is on the hot side and the Conc coil does not work as good in the hotter ground around here.

Like I said earlier. try AM with 2 tones and also if you can, go to that place when the ground is super dry.

I know what your talking about when you say " averaging " I know some ppl will say that the Xterra will not average the 2 targets in the hole but I've seen it do it when their is like a nickel and a dime in the same hole, but I don't notice it so much when their is a coin and a piece of iron in the hole.

As far as what coil would work better, I have no clue, but I like the 10.5 MF DD and I look for those area's that is loaded with iron at parks and schools and that's where I find the old coins most times.

 

[pulltaber]

Ok, Mark & pulltaber: Interesting that you're saying you've specifically tried this in the famous "nail board test", and found that the 6" MF was better than the 6" HF, in that test. Hmmm, because I'd have guessed/assumed that HF, by it's very inherent traits, is better as seeing through (aka "averaging") rusty iron nails, than Low or Mid-frequencies.

Tom_in_CA, I have been MD'ing since the 70's and have not always believed what others said till I seen it myself, but I respect their knowledge and experience.So why not do the nb test yourself and let us know the results.

Mark in S.E. IA ; I use AM and two tones in nails most of the time or till the 99 tones gets on my nerves in high trash,but it will still not pass the NB test

 

[Tom_in_CA]

n/t

 

[Tom_in_CA]

.....So why not do the nb test yourself and let us know the results........

Ok. I will report back to this forum on the results of the MF vs the HF in this iron zone that I speak of.

 

[Old Longhair]

OK, I've been holding back to see what the replies would be, but now I'll put my 2¢ in.
First, I put no stock in anyone's nail board test, or any other test that's not conducted in real world circumstances. If you've ever played around with GB and noticed the differences that it can make relative to target response, then you know that the machine has to balance to something accurately or the response will be less than optimal.

As far as frequency selection goes, if high conductors are the desired target, and if iron makes up most of the "trash" being sorted through, then 3kHz is what I'll choose almost every time. The response difference between high and low conductors is dramatic. Enough so, that I often go to "hunted out parks" and dig nothing that doesn't have iron in the hole. When I was testing the 6" Digger coil I took it to two of the most iron/trash infested sites that I knew of, and I found coins and jewelry at both sites. In fact, the first silver that I found with it was rust stained from a bolt that was laying against it. The biggest trick to finding anything "through" iron or any trash is approaching it from enough different directions, coupled with going slow enough.

HF coils are always my last choice for general use. Around here they will make you want to throw your machine as far as you can, unless you're digging everything anyway. I ONLY use mine at the beach, where I AM digging everything. They aren't capable of accurately delineating high conductors from large or solid low conductors, and you'll spend a lot of time practicing and learning minor tonal nuances to be able to avoid much iron (except in Prospector Mode), during which time you'll also clean out most of the crown caps that may be at the site. Since picking up my 705 I've only sold one coil, it was a 10.5" HF DD, and I've never missed it.

MF coils, due to their having virtually uniform target segment bin widths, are known to be the most honest across the detection range. They are a good choice for general hunting, and for inland use they are what I'll switch out to if the site or targets sought dictate something other than my preferred LF coils.

 

[JimmyCT]

Great post and super information. Glad the subject was brought up and discussed.

 

[Tom_in_CA]

Long-hair: Thanx for the input. That puts you too in the camp of persons saying that there is nothing magic about HF, in "seeing through" iron then.

Then all you guys's inputs make me want to try out the 6" MF and 6" LF on this. To pit against what I have already seen with a 6" HF. The 6" HF I saw (on a 505, in that case) was spanking other machines in a nail-riddled zone. Even spanking famed 2-filter Tesoro type machines (silver sabre, shadow x2, etc....) which are normally good at the "seeing through" trick (albeit with their other drawbacks).

So I will track down the MF and LF coils, and report back to you forumites the results. At present, I only have a 9" MF. And that wouldn't be a totally fair test of comparison, since it's bigger. So as soon as I round up the other 2 types of 6" coils, I'll try them over flagged spots (so that it won't be an air test "nail board" type test).

Also in this test will be the new Racer detector, which is getting "latest/greatest" reviews on the net, as you all know. A buddy of mine will be bringing that. It will be interesting to pit that, against this, on flagged targets. Because that Racer is also getting a lot of press for "depth", as you know. And *normally* any time a machine starts to enter the "power-house depth" class, is when you can count on the trade off of less ability to separate and see through (aka "average").

We shall see

 

[Crash67]

Yes please keep on testing and theorising in the meantime me and my Xterra and 3 KHZ coil will be out finding silver

 

[Old Longhair]

Tom, my purpose in waiting to post my opinion was to illustrate that what works here might not be optimal where you are. Everyone's circumstances are different, and part of the beauty of the Xterra is it's ability to be configured accordingly. So by all means find what works for you. There are a total of twelve authorized coils available, none of which are redundant, so combined with all of the other user controllable features you shouldn't have too much trouble selecting a couple to suit your needs.

Just keep in mind that a certain amount of it is physics that remain constant, like high conductors such as silver and copper giving a better response to lower frequency, and higher frequency being more sensitive to smaller and lower conductive targets like small gold, nickel, and pewter. In mild soil conditions a concentric coil will see deeper, but where conditions are hotter (ground phase typically below 28-30) a DD is likely to have an advantage due to the lesser total volume within the detection field to compensate for. And separation is not just a left/right thing. Length heel-to-toe limits separation capability, so if trash density is sufficiently heavy a smaller coil will allow less masking, at a cost of some depth.

 

[Tom_in_CA]

thanx ! N/T