705 "harmonics"

[mojotrout]

are there any Youtube videos providing examples of the AM 99 tone harmonics Digger describes in his Manual? I am getting soooo much high tone/low tone mixing-- to the point that I cant effectively search moderately trashy areas anymore without going insane. Im also getting two differnent responses that could be described as "harmonics" -- one is where I get several distinct target responses in quick succession, giving audio responses from both high to low and low to high. The other is when a single response starts low and stretches into high (or vice versa) in a single response (like tuning an old AM radio). Im a little confused on which one is the "harmonic" response that can be used to ID iron pretending to be silver/copper and vice versa.

I reaize that I should expect some iron to give a high tone response, but in some trashy areas, I get high tones almost every swing, and I know that someone wasnt sprinkling my town with buckets mixed with dimes and nails!

My settings are as follows-- GB tracking on (GB numbers between 15-25 when auto GB), sens 25-28, noise cancel at -1 to +1, AM, 99 tones, Thresh at 5-9 depending on noise levels around me. Im using the 9 inch 7.5 kHz coil.

I think it would help me if I could HEAR an example of what Digger is describing in his Ebook. Any other advice on eliminating some of the confusion with iron would be appreciated!

 

[surfchunker]

probably just wrapping around but hopefully Longhair will jump in, he uses all tones ... a digger coil will also help a lot to separate the items in the ground

 

[pax]

have you tried that same area in manual or auto GB with the sens a bit lower,its just an idea you might try

 

[Digger]

one is where I get several distinct target responses in quick succession, giving audio responses from both high to low and low to high. The other is when a single response starts low and stretches into high (or vice versa) in a single response (like tuning an old AM radio). Im a little confused on which one is the "harmonic" response that can be used to ID iron pretending to be silver/copper and vice versa.

I reaize that I should expect some iron to give a high tone response, but in some trashy areas, I get high tones almost every swing, and I know that someone wasnt sprinkling my town with buckets mixed with dimes and nails!

My settings are as follows-- GB tracking on (GB numbers between 15-25 when auto GB), sens 25-28, noise cancel at -1 to +1, AM, 99 tones, Thresh at 5-9 depending on noise levels around me. Im using the 9 inch 7.5 kHz coil.

based on the coil you are using and the target responses you describe, I'd suggest the second one is what I describe as harmonics....a blending of tones on a singular target. The first one sounds like you have multiple targets during your sweep. Consider slowing down your sweep speed in those congested areas, to better separate targets. Try lowering your sensitivity in those "congested" areas, to allow for a less amplified response. And you might also consider a smaller DD coil in those areas with multiple adjacent targets. HH Randy

 

[Old Longhair]

based on the coil you are using and the target responses you describe, I'd suggest the second one is what I describe as harmonics....a blending of tones on a singular target. The first one sounds like you have multiple targets during your sweep. Consider slowing down your sweep speed in those congested areas, to better separate targets. Try lowering your sensitivity in those "congested" areas, to allow for a less amplified response. And you might also consider a smaller DD coil in those areas with multiple adjacent targets. HH Randy

'Ya beat me to it! I saw his post on my phone, but didn't want to do all the necessary typing 'til I got home....just now.

 

[surfchunker]

there ya go from two of the best XTerra guys around

 

[mojotrout]

Hi Pax, Digger, thanks for the suggestions. I have tried Auto GB and tracking GB but not manual GB. To be honest, I didnt get enough time in with it in Tracking AND lowered Sens (from 28 down to 25) so I cant say if it had a difference. The frozen ground is keeping me from going out and figuring this stuff out on my own so I was hoping others had similar issues and could steer me straight.

Im going to try even lower sens, as per both of your suggestions, but I need 6-7 inches where Im at. I get that and then some in the lower minerialized sod /yards/ROWs, especialy when they are moistened by rain/sprinklers. How much lower can i turn my sens down whlie still getting down that deep in average conditions? I realize thats a tough question to answer, but on average, can I go well into the teens and still expect 6 inches on a dime or do I generally need to stay in the low twenties? Im working the MF 9.5 coil.

Digger, Im swinging pretty slow and taking my time and trying to absorb as much info as possible, so I think Im ok with my swing pace (about 3-4 seconds from one side to another).However, you are right in that I should consider a DD coil. The Digger 3khz is likely in my future...after it thaws out around here.

 

[surfchunker]

frozen ground can make them wacky .... I went out to today and it was going crazy where it was froze, but once I got to some thawed out ground it was good to go

 

[pax]

your right about that surfchunker

 

[mojotrout]

Aaaaaaaahh......that might be a big part of it. This issue has really come on over the last few months when the cold came in. I didnt think about the ground temps so much beause I was also at new locations with different site conditions than my summer haunts.

 

[surfchunker]

in this little parklet I've been hunting it normally GB's about 22 or so and it was 38 and going off like crazy and I just knew that wasn't right, so I walked to where the ground was thawed out and it GBed right at 23 this time and was acting normal. I've been running the sens. in the mid to low twentys but that was still too high over that froze gound.

 

[Digger]

I have tried Auto GB and tracking GB but not manual GB. To be honest, I didnt get enough time in with it in Tracking AND lowered Sens (from 28 down to 25) so I cant say if it had a difference. The frozen ground is keeping me from going out and figuring this stuff out on my own so I was hoping others had similar issues and could steer me straight.

Im going to try even lower sens, as per both of your suggestions, but I need 6-7 inches where Im at. I get that and then some in the lower minerialized sod /yards/ROWs, especialy when they are moistened by rain/sprinklers. How much lower can i turn my sens down whlie still getting down that deep in average conditions? I realize thats a tough question to answer, but on average, can I go well into the teens and still expect 6 inches on a dime or do I generally need to stay in the low twenties? Im working the MF 9.5 coil.

Digger, Im swinging pretty slow and taking my time and trying to absorb as much info as possible, so I think Im ok with my swing pace (about 3-4 seconds from one side to another).

I wouldn't recommend using a manual ground balance on the 705. In fact, if you want to lock in on a specific ground phase setting, by all means, use the Auto GB. But since the 705 has tracking capabilities, I'd be using that. And personally, I would be using Tracking with a positive ground balance offset.

If you Noise Cance the detector properly (that means while holding the coil parallel to the surface, about a foot above a spot that doesn't have any targets) and use Tracking with a GB offset, you can then adjust the Sensitivity to a point that just barely falses when you sweep the coil......then back off the Sensivity one click. The numbers don't really mean anything, other than the larger the number....the higher the Sensitivity. Numbers vary on soil conditions. But remember that having a Sensitivity setting that is too high can cause false discrimination. (reflective signals....e.g. bright beams in fog) If you've not read the information on Sensitivity that I put in my eBook, I'd encourage you to do so.

If you still have problems separating targets with the stock coil, another suggestion would be to raise the coil and sweep over them in Prospecting mode. Once you have identified the exact location of each target, switch back to Coin/Treasure and put it into Pinpoint Sizing. Then sweep each one, and you'll get a pretty accurate TID.

Your sweep speed sounds good......3-4 seconds from one side to the other. Just keep the coil flat to the ground, trying to not let it bounce or bump the surface.

HH Randy

 

[Old Longhair]

But remember that having a Sensitivity setting that is too high can cause false discrimination. (reflective signals....e.g. bright beams in fog) If you've not read the information on Sensitivity that I put in my eBook, I'd encourage you to do so.

Bingo! This gets my vote. As a matter of fact I was thinking of that very passage while reading his description.
And being frozen ground does make a HUGE difference, especially if it was wet ground before freezing. It would be interesting to know how the ground matrix around a target is affected by freezing. Hmmmm...

 

[mojotrout]

thanks guys, good information! Im going to go out and hit my coin garden and mess with the settings you suggested. I will get back with you with results. It is supposed to be in the fourties this week so maybe I can get out and get some info before / after freeze...

 

[Digger]

Just my opinion......although pure water is not a conductor of electricity, moisture in the soil can enhance the conductivity of that soil. When the soil passes electrical impulses more readily, targets can be detected at greater depths. As the wet soil freezes, it expands.....much like water expands when you make ice cubes. As the soil expands, the resistance of the soil is increased, thus the conductivity is decreased. In addition, as the soil freezes and expands, it separates itself from the target, reducing any effects of what some refer to as the "halo effect." Theoretically, you should be able to detect as deeply in frozen (non-mineralized) soil as you can with an airtest. But not as deeply as you might when the soil is wet, but not frozen. Naturally, mineralization levels and target properties will cause substantial variations. Again, just my opinion. HH Randy

 

[Old Longhair]

Ahhh...but does it separate from the target? We've all dug coin balls before. Is there any reason that the soil couldn't be compressed around the target as it freezes and swells? Being a better conductor of heat/cold than dirt our copper and silver targets likely freeze a fraction quicker than the soil around them when the temp reaches their depth.

There could also be a correlation to be made regarding the influence of conductive minerals between thawed and frozen ground. Being so close to the world's largest salt mine, levels of conductive minerals here varies greatly anyway, but maybe I should do some experimenting. If I ever see a bare patch of ground nearby again (meaning not snow covered), I'll snap the stock 9" MF coil on and take some measurements to compare to at various times of the year to see how moisture and temperature effect them.

 

[Digger]

The soil might swell, but the coin won't. Like you, I've dug a lot of coins from frozen fields. And I seldom have to wipe off any frozen chunks of dirt stuck to them. The targets seem to "break free" of the frozen dirt (coin balls), usually as I pry them from the ground or when I roll it around in my hand. It is as if there is a void between the coin and the frozen soil. My theory is that the moisture in the soil, which has expanded that soil, has expanded away from the target, creating that void. But again, that's just my theory. HH Randy

 

[surfchunker]

wow some deep stuff ... I know the other day where I usually GB and set it up it was froze and lots of Ice crystals where the ground was very wet when it froze and it went crazy with the digger coil ... once I moved away from there 20' it cleared up in the thawed out ground

 

[Mark in S.E. IA]

I have always had problems MDing when the ground is starting to freeze in the fall and in early spring when areas are still froze. The MDer does not act right when I go over frozen ground. It acts like the GB is way off and I can not detect coins much over a few inches deep, if even that deep.

 

[atomicscott]

Low tones mixing with high tones on a SINGLE target usually indicates it's junk. That's why it's important (for me) to pinpoint and size up the target to make sure I am getting a scan of ONLY the SINGLE desired questionable target. Sure there is a possibility that it is a good target next to an iron target, but once you pinpoint and isolate the target, you should be able to get a repeatable high tone IF it's a good target. Good targets will lock on much better (easily repeatable). If the ID is say, a 40 (high tone) but bounces to a -8 (low tone), it may likely be rusty iron that is similar in shape and size of a coin. If you get high tone in one direction only and low in the other, it's usually junk for me. The sites I hunt sound like a machine gun with all the iron targets, at least 10 targets per swing most of the time! Upon swinging about 3.5-4 seconds per swing, I swing back over any high tones real quick, if I can't get a repeatable high tone at all, I move on. If I get an intermittent high tone, I will then circle the target and scan & see if it drops down to a - number. If it does, it's usually iron. You need to trust the machine, I have been finding some wheats in completely iron infested demolished home sites. The tones were easily repeatable, even with the surrounding iron tones. I have confidence that I will find the coins on top of, or next to iron, but coins under iron is another story! So, if you are swinging slow enough the good targets will be noticeable over the surrounding junk. This is just MY experience with my machine using the 18.75 kHz 6" DD coil. HH