Impact depth test on coin (UK) .

[Doctorcoinz]

I decided to bury a pre - Decimal penny in my back garden today to test the 7.5 x 4 Coil. I buried the coin at a measured 4 inches. I tried all of the programs on the machine but I could not get a reading from the coin , I tried the 3 different frequency's too but could not get a whisper from the coin. I put the standard 11 x 7 inch coil on the impact and then the coin was detected with a good signal at 4 inches , re planted it at 6 inches and could still detect it no problem.
My garden is littered with nails and ash plus other junk metal under ground. I was surprised just how much depth loss the nails and bad soil caused the 7.5 x 4 to miss the large penny. I detected the rest of the garden for any lost coins with the 7.5 x 4 and found a decimal penny and a 20 .pence coin. shallow though. With the small 7 x 5 coil I found the detector to have very good target separation but I know I am not going deeper than 3 inches or so on a large coin in bad ground like mine.
I think in clean ground the 7.5 x 4 would easily have nailed the coin. at well over 3 inches.

 

[Cal_Cobra]

I'm leaving the 11"DD on mine, would love a 10" closed DD like the Racers have, that's an awesome coil, almost as stealthy as the smaller coils, and darn near equal coverage, oh and it finds the goods on the Racers!

 

[Doctorcoinz]

From what I see the small coil wont punch down through bad dirt with nails in the ground
on the impact. A pre decimal penny is massive. I am wondering if my small coil is bad for it not to hit a large copper coin at a mere 4 inches!. The rusty nails are the problem though probably , massive depth killers are nails ..

 

[Doctorcoinz]

I tried the 9 x 5 coil today on my 6 inch deep penny , sad to say I cant get a whisper from the coin. Only a low iron buzz, In air the 9 x 5 coil can sound off a penny at maybe 19 inches.if set right.
In ground the spot where the penny is planted has defeated the Impacts circuits...There is a nail close to the coin maybe a little above it that is "absorbing "the signal...
I can get detection depths in AIR with the impact that equal the Bliss Tool detectors,,,, The air tests are the best I have seen on the impact except like I say the Blisstool is on par with it...... I am waiting for good conditions to come so I can get some deep things. I am not getting anything particularly deep yet with the impact...

 

[Monte]

almost always going to be less that perfect when buried and/or when there are masking trash targets under, over, beside, nearby or much shallower than the target and closer to the stronger portion of the EMF. Coins or other desired targets can be masked or partially masked, and 'masked' can mean hidden or undetectable or just partially effected so as to limit the depth and/or degrade the audio and visual TID read-out.

As for the Impact, it is one of the best general purpose detectors I have ever used! There is no such thing as a 'perfect' detector, so my Impact devoices are supported in my arsenal by my Nokta FORS Relic and FORS CoRe units because all of them have their strengths. My CoRe and Relic units get about an equal portion of my detecting time, like maybe 30% each, and an Impact is working 40% of the time. That's today and for the types of sites I've been Relic Hunting. When we shift into late fall and winter, when my urban Coin Hunting time increases, I am sure the Impact will be seeing about 80% of my hunt time.

There are some different search coil assignments between these models as well. My most-used CoRe has the 'OOR' coil mounted which is not available for the Relic or Impact. My most-used relic and Impact devices each have the round 5¼" DD mounted. For mid-sized coils one of my Relic's has the solid-body 5½X10 Concentric coil mounted, which is not available for rather the CoRe or Impact.

The mid-sized coil I use most often on my production Impact is the new open-frame 5X9½ DD and it is working great for all of the low-to-moderate trashy sites I hunt. I like it so well that I plan to acquire one for the FORS CoRe and FORS Relic accessory coils I carry along, each mounted on their own separate lower rods. The Impact will also be using a search coil that is not available for the CoRe or Relic models when I mount up the new round 7" Concentric. I will be very interested to see how that coil might work in the trashier Relic Hunting locations where ferrous debris tends to be in greater abundance, but I anticipate it excelling in the way of tighter, more consistent TID read-outs and possibly depth of detection in 'quieter' sites where there is less masking trash. No doubt the new 7" round Concentric coil will likely become my primary-use Coin Hunting search coil for most urban public parks and access areas as well as for searching private yards.

Getting the most out of any detector is a matter of search coil selection, search mode chosen and settings used, plus making use of the most efficient sweep speed. With all of my Regular-Use Detectors, TID equipped or not, I get the most effective performance by using a slow and methodical sweep speed. Of course 'slow' is a matter of individual interpretation, but each detector operator will have to determine the most effective sweep speed for them, the coil used, and the site challenges they deal with. In most cases a too-fast sweep can impair overall performance afield. Naturally, each individual will need to learn what 'too-fast' means to them by learning when afield.

The new 5X9½ DD is a splendid search coil for a lot of my detecting, and that includes providing me with acceptable depth-of-detection in decent mineralized ground environments.

Monte

[size=small]Oh, for those who might wonder how the Impact or any other detector I use performs with after-market search coils, I can only share my testing time when I have borrowed one of those coils, or detector with an after-market coil mounted, because I have long been a firm believer that I can usually find the best coil for any detector model from the detector manufacturer rather than from a different search coil supplier.[/size]

 

[Doctorcoinz]

Very good post Monte , it's amazing just how many good targets are masked out with ferrous , also a great many good targets are plain just too deep for current vlf detectors..
Burying coins in a nail loaded garden proves the fact , depth is killed by 80% or more in nails..

 

[hairymonsterman]

Your correct there, even a nail 10" away on the surface from your target can make you miss it. I can get a pre decimal penny at 11" in my soil which reads 3/4 full mineralization on my Deus which is pretty dang good, my Racer 2 gave up at about 9", but put the smallest tack nail, a lead pellet etc below the surface and the coin will disappear.

 

[Mudwhale]

almost always going to be less that perfect when buried and/or when there are masking trash targets under, over, beside, nearby or much shallower than the target and closer to the stronger portion of the EMF. Coins or other desired targets can be masked or partially masked, and 'masked' can mean hidden or undetectable or just partially effected so as to limit the depth and/or degrade the audio and visual TID read-out.

As for the Impact, it is one of the best general purpose detectors I have ever used! There is no such thing as a 'perfect' detector, so my Impact devoices are supported in my arsenal by my Nokta FORS Relic and FORS CoRe units because all of them have their strengths. My CoRe and Relic units get about an equal portion of my detecting time, like maybe 30% each, and an Impact is working 40% of the time. That's today and for the types of sites I've been Relic Hunting. When we shift into late fall and winter, when my urban Coin Hunting time increases, I am sure the Impact will be seeing about 80% of my hunt time.

There are some different search coil assignments between these models as well. My most-used CoRe has the 'OOR' coil mounted which is not available for the Relic or Impact. My most-used relic and Impact devices each have the round 5¼" DD mounted. For mid-sized coils one of my Relic's has the solid-body 5½X10 Concentric coil mounted, which is not available for rather the CoRe or Impact.

The mid-sized coil I use most often on my production Impact is the new open-frame 5X9½ DD and it is working great for all of the low-to-moderate trashy sites I hunt. I like it so well that I plan to acquire one for the FORS CoRe and FORS Relic accessory coils I carry along, each mounted on their own separate lower rods. The Impact will also be using a search coil that is not available for the CoRe or Relic models when I mount up the new round 7" Concentric. I will be very interested to see how that coil might work in the trashier Relic Hunting locations where ferrous debris tends to be in greater abundance, but I anticipate it excelling in the way of tighter, more consistent TID read-outs and possibly depth of detection in 'quieter' sites where there is less masking trash. No doubt the new 7" round Concentric coil will likely become my primary-use Coin Hunting search coil for most urban public parks and access areas as well as for searching private yards.

Getting the most out of any detector is a matter of search coil selection, search mode chosen and settings used, plus making use of the most efficient sweep speed. With all of my Regular-Use Detectors, TID equipped or not, I get the most effective performance by using a slow and methodical sweep speed. Of course 'slow' is a matter of individual interpretation, but each detector operator will have to determine the most effective sweep speed for them, the coil used, and the site challenges they deal with. In most cases a too-fast sweep can impair overall performance afield. Naturally, each individual will need to learn what 'too-fast' means to them by learning when afield.

The new 5X9½ DD is a splendid search coil for a lot of my detecting, and that includes providing me with acceptable depth-of-detection in decent mineralized ground environments.

Monte

[size=small]Oh, for those who might wonder how the Impact or any other detector I use performs with after-market search coils, I can only share my testing time when I have borrowed one of those coils, or detector with an after-market coil mounted, because I have long been a firm believer that I can usually find the best coil for any detector model from the detector manufacturer rather than from a different search coil supplier.[/size]

Great post Monte!
What's missing here is his freshly buried target. I have done this with many detectors to find exactly nothing. The target needs to be in the ground for an extended period of time to have the dirt compressed around it as in a natural found state (many rainfalls). Fresh buried targets are sometimes worse than just air testing. IMHO...

 

[Monte]

target type, size, shape and duration at a fixed buried position, can really make a lot of difference.

Great post Monte!

What's missing here is his freshly buried target. I have done this with many detectors to find exactly nothing. The target needs to be in the ground for an extended period of time to have the dirt compressed around it as in a natural found state (many rainfalls). Fresh buried targets are sometimes worse than just air testing. IMHO ...

Through the years I have been asked, or I have responded and made suggestions when I have read, 'about how deep with the detector go'. I also caution people about misunderstanding 'depth' and how we might interpret detection depth, or anticipate potential target response from buried targets.

Coins, like other metal or solid objects, don't 'sink,'; but are either naturally covered by grass, weeds leaves, or erosion. Sometimes erosion and wind-blown conditions can also uncover lost objects. They might end up located deeper than a surface drop due to build-up over time, or perhaps from disturbance, such as plowing or tilling, water action from waves or run-off and that causes more of a fluid state when specific gravity goes to work. Also, many older coins and other targets are 'repositioned' due to human or animal foot traffic and activity, or by wagons, vehicles and other causes.

I always suggest that it is best to use three methods to get an idea of a detector and/or coil's potential performance using thee methods, not just one.

1.. Perform an 'Air Test' with an assortment of the targets you anticipate searching for. Wave the test samples across the center-axis of the search coil as if laying 'flat' like laying on top of the ground. Also test them at various canted angles to see how the signal, and both audio and visual responses, might vary. Those might be close to an 'ideal' response where there is no masking target nearby nor ground mineralization factored in.

2.. Bury the same test samples in the ground at depths of about 2", 4" and 6", at least, and compare their responses. Again, bury them 'flat-to-the-coil, as well as at odd angles, and be sure to replace all the soil as best you can. The reason for this testing is to include the ground mineral component that a detector must deal with afield. This will come close to what might be expected in disturbed ground, such as a tilled garden or yard or a plowed field.

3.. Go out and hunt up some naturally lost targets in an assortment of sites that were naturally lost long ago and have had ample time to settle and have ground naturally compacted about them. This nothing but taking your detector out hunting just like any day, but being attentive to the location, mineral make-up, and target position. Compare the targets you find ion an every day hunt with those you test sampled in '1' and '2' and you'll have an idea of what to expect in the real world.

Nothing is going to be 'perfect' so do the best you can on your part and with the best detector and coil you feel confident in. There are just too many variables involved to know what to expect out of a detector set-up without also knowing the site environment and ground make-up the search will be conducted in.

Monte

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