Coin Garden Testing Using SunRay S-5 (5.5inch), Tornado 10", & SEF 15x12"

[Critterhunter]

This is the very initial results with a new test garden I just did in my yard and the Sunray S-5 coil. The other coils will be added shortly, and after the garden has had time to "heal" down the road the same tests will be conducted again and a new chart posted for comparison. I just threw this chart together real quick so the format and/or testing specifications & legend table indicators may change as I fine tune things.

I also plan to add other coins to the garden at shallower depths less than 7", but with various forms of iron or trash masking them. That should provide a better proving ground for the S-5 against the other coils as it's probably going to be unable to reach the current target depths. Those masked target tests should also be real interesting to see how well the SEF separates compared to S-5 as well as the 10". I believe it might very well do better than the 10", but I also suspect it might surprise me with certain targets compared to the S-5. I believe the unique "hybrid" coil dynamics of the SEF coil might hit multiple targets in the soil better than a typical DD, regardless of size.

 

[Critterhunter]

After taking more time to look at the chart it's a bit confusing in various ways. I think I listed certain things out of sequence. I'll try to change the format to make it more simple to follow with the next update when I do the other coils for their "freshly" buried testing of these targets.

 

[Critterhunter]

Here's the next "update" in a new format, which will probably change still yet as I try to list things in a more clear and direct manner.

I did some very limited testing with my 15x12" SEF coil before the rain hit today and was surprised to find that it would hit the 11" deep quarter which is halfway on edge! If I was sweeping in normal fashion it quickly alerted me to it's presence with a good audio hit that would be hard to miss. Doing the Sovereign "wiggle" over the target easily caused the ID to climb and then lock onto 180, and with perfect audio! This was sweep over the width of the coin. If I moved around and swept over it lengthwise (meaning in the same direction as the coin's edge) the target would go to a null. I was also able to pick it up in Pinpoint, which is very surprising because thus far PP seems to max out for me at about maybe 9".

There is a large metal signal some 5 or 6" away from the quarter as described in the picture file but I was easily able to see the quarter and it separetly with the SEF, with plenty of "dead air" between the two to confirm that I wasn't picking up a false hit from the trash which might cause me to think I was reading the coin signal. In both PP and discrimination I could easily separate the two targets distinctly, and no amount of wiggle around the trash at the same distance in different areas would cause any kind of false coin hit either, so I'm completely sure the good coin signal was just that. It's precisely where I marked the quarter being buried. Very impressive considering the ground hasn't had time to heal and form a halo, as well as this being heavy clay which isn't as easily tamed as normal black soil.

I didn't have time to attach the two picture files together as one chart but like I said this is way early in design anyway...

 

[Critterhunter]

Forgot the most important part of that quarter being detected. I was running in Auto. I never would have thought that it would hit that coin in Auto, but with the coming rain I had no time to play with manual sensitivity. I'm right next to some house power lines and at max manual sensitivity the unit was falsing on me bad. I plan to try noise band 1 without lowering sensitivity and if that doesn't work then I'll lower sensitivity to something stable for tests that way as well. That's why I've listed just about any setting you can think of in the chart. I'm curious which will do what on various targets at depth.

One thing that concerns me is this...Yesterday I went to a known deep coin spot for a second try there with the 15x12. I hunted a good four hours and found nothing old let alone past say 8" in depth. The only "keeper" I dug was a 1933 Canadian penny that was probably 8 to 9" deep and gave me a perfect penny signal. This site is both large with plenty of area to hunt and has good deep black soil. It's not uncommon to find clads 6 or 7" deep. Heck, even the new State quarters are already 3 or 4" deep when you find them some times. Rosies and Mercs are 6 or 7" deep or deeper as well as wheats. A friend hunted this spot for a few hours once and I saw him dig a Rosie and a Merc in separate holes that were about 9 1/2" deep. Other even older coins including barbers, seateds, a shield nickle, and even an 1842 Canadian half penny bank token have from come this spot over the years.

What I know is that deeper coins are present than the 7.5 to 8" max depth we've beat this spot up over the years with our Whites units. The short hunt with the Etrac proved that, since it popped a few silvers a few inches deeper in a short amount of time. Also, like I said this spot is very large so it would be hard for anybody to cover it all. So why in two hunts thus far have I not pulled a deep silver or even a wheat out of this spot even a bit deeper than the other machines can reach? I'm able to run at max sensitivity with no falsing but now I'm starting to wonder if perhaps even if sensitivity is stable at max the SEF coil might be saturating the GT with too much gain and somehow be costing me depth instead of giving me it. After seeing the SEF hit my test garden quarter at 11" in auto with a good ID and audio and also after digging that sinker a while back that was 11" deep and also had good audio/id, I'm starting to wonder what might be going on here. Yea, it could just be that I haven't passed over a coin yet at this spot with the SEF but I highly doubt that based on all the wheats and silvers we've dug all over that place over the years.

Now I want to be perfectly sure as well that that test garden quarter hit is in no way a false hit caused by the nearby large trash target. I'm pretty sure it isn't based on the dead air between the two and the fact that no false coin hits can be produced by the trash at any other spot. Just the same, I'm going to dig out that trash target and then re-test my findings to make sure I am in fact picking up the quarter. My field experience so far has given me serious doubts. I had dug silver quarters on edge in auto at about 7 3/4" or so, though. Yesterday I also dug a tiny shoe eyelet at 7 and 1/2" deep that banged out loud and clear. I would figure if I can hit that then a silver dime 2 or 3" deeper wouldn't be a problem at all for it.

I also did some air testing there on a clad dime and found at max sensitivity it looked well over a foot in depth, but I didn't have a ruler with me to measure. I came at the dime from a distance until the dime gave a perfect ID and audio. The audio was soft but plenty loud enough even at this extreme fringe, and the ID locked right on. Seems the instant the GT starts picking up a target at all it locks right in to the proper ID/audio. In auto it looked more like 8 to 9" of depth, but we all know Minelabs go deeper in the ground. Next time I'm at this site I plan to stick a silver dime in the ground and use a ruler to measure maximum detecting depth with the SEF and max sensitivity. I'll then try Auto and also a lower manual and see what gives.

One good thing is the GT identifies nickles real easy. I must have walked out of there with 10 or 11 nickles and I knew each one was in fact that based on the audio and the VDI locking in somewhere in the 141 to 146 range. Nickles almost never bounce around on the VDI, or at the very least will only change by a digit. They also don't have the sick sounding warbly audio of other trash in that range.

I've for sure got to do some depth tests of the 10" versus this coil. So far the two deepest coins I've ever dug on any detector were a V-nickel and an Indian (two separate holes) that were somewhere in the 9 1/2 to 10 1/2" range or so from memory. I couldn't believe how hard they both hit and gave the correct ID. I love the SEF so far in many ways but I need this thing to prove to me that it is getting as deep or deeper than the 10" by finding coins in the field. A test garden or that sinker I found don't quite do it for me when it comes to confidence. Perhaps the 10" gets deeper. I don't believe that yet but still the proof is going to be in the results of testing and actual field use.

 

[Critterhunter]

Sometime soon I'm going to be constructing a wood structure (with no nails) to mount a coil on. Off the corner of this box will be a PVC tube with an elbow bend which can be both adjusted down in length and also pivoted for swinging directly under the coil. I plan to mount various targets on this and use this device to to precise measured air testing of the various coils at various sensitivity settings. Since the target and coil distance from each other will be statictly set there will be no doubts as to the exact distances measured. I also plan to do this both in my backyard where RF noise is present to indicate which of the coils gets best depth and stability, and also in a remote location where pure air depth of the coil will be demonstrated with no RF present to insure maximum possible sensitivity settings. Auto will also be tested. I'll put a chart together and throw it up when done.

The other thing I plan to investigate with this device is the shape of the coil signal. I think I have a way to "paint" the signal shape. I'm real interested in seeing how the SEF's signal compares to the 10". I have a few thoughts on that that I want to prove for myself.

 

[Critterhunter]

Got my air testing rig done for precision depth measurements of my coils. This way there is no guess work as to depth by using other methods. The adjustable PVC pivot "arm" holds the target and moves back and fourth while the coil remains stationary. I constantly alter the speed of the target until the optimum speed for best response is found, which always turns out to be the short/fast Sovereign wiggle most people do on real deep targets to obtain the best target ID and audio. The target starts out at too far away and is slowly decreased in distance while doing the wiggle until the first moment the detector locks into the proper ID/audio. Once that is found the PVC arm will remain in place without moving so I can then measure the distance, taking into account the width of the plywood the coil is mounted on top of in the total mesurement.

This initial air testing was done in my garage where there is plenty of RF noise, so while the results were pretty good I would expect even better results in the field. I plan to take this setup out to a remote location to and test them all again to post those results as well. Also, we all know that most say BBS and FBS machines don't air test as well as other machines due to them needing a ground load to compare signals to. I can already say that do to the RF noise present in my garage the amount Auto adjusts down to is less than what I've seen by eye in the field when doing air tests. For instance, the S-5 in Auto appears to get more depth by eye than what it did in my garage. And, the other two coils in max sensitivity or even at the 2 O'Clock position were unstable due to the noise factor, which makes obtaining a locking ID and tone harder to acheive. I expect in the field that the less RX gain noise present will improve those depths a good bit. Still, the numbers posted are pretty impressive for any machine, let alone a Minelab that doesn't like air even in freshly tilled ground.

As you can see the SEF coil in Auto matches the 10" at max sensitivity, and has a good 1 & 1/4" more depth at max then the 10". From air testing in Auto in the field this coil looks to get about 11" on a silver dime.

The below tests were done using the following...Discrimination. Iron Mask ON, Noise Band 2. Threshold Mode. Volume At Max (No Headphones). Discrimination and Notch At Zero. I also drilled a hole through the test rig at dead center of the target in it's sway angle so that the coil could be properly centered. Once max depth was found I also slightly moved the coil around to see if it was any deeper slightly forward or back from dead center to insure maximum depth numbers. The target used was a Mercury dime. More tests to follow down the road, including the coin garden results.

Sorry about the font style. For some reason Paint wouldn't allow me to use anything other than Westren.

 

[Critterhunter]

One more thing for now...Although the SEF coil shows greater depth than the 10" that doesn't automaticly translate into greater depth in the ground. Even if the coil is stable at a specific sensitivity setting and both coils are ran at the same exact setting it might be in fact that the ground matrix washes out target signals due to the amount of ground the machine is processing with the larger coil versus the smaller one. I'm not saying the SEF won't get better depth, but I am saying that I have yet to prove that to myself in actual ground conditions. My soil is moderate to heavy in mineralization at most spots, with low mineralization at others. It may be that this size coil will only show a depth advantage in the lower mineralized soils, but that is only a theory at the moment. With that said, that's why I'm in the market for a used 12x10 to compare to both coils. It's slightly larger foot print than the 10" might not push the ground processing past it's limits of deminishing returns, increase it's depth a bit in even highly mineralized ground. All the above is only something to investigate and with not enough data at the moment. I'd say just about every field report I've read on these coils by people state that the 15x12 was the deepest coil they've ever used, even in highly mineralized ground. They also say the 12x10 is deeper than even the 11" pro coil for the most part. Either way, both are great coils for many other reasons other than just the potential increase in depth.

 

[Critterhunter]

When I do the testing again in a remote location with no RF noise it will be interesting to see if Auto then produces more depth than the 2 O'Clock position, and just how close it gets to max sensitivity. That will give a general rough idea of just how high Auto adjusts in low RF noise locations. I think it's more prone to this factor (RF noise) at it's calibration that the content of the ground matrix.

Somebody in the T2/Omega forum just posted some in depth air testing on those machines. It's an interesting read and also a good comparison to what the Sovereign is doing in the air for reference.