SMF

[DigDog]

I'm still puzzled why you're so surprised by it. If you have a test garden, do this simple experiment:

1. Find the deepest small target (such as coin) your machine can reach at max sensitivity (this is important, as tx always blasts on full power, sens/gain only affects the rx processing), or as close to full sens as EMI permits
2. Pinpoint its exact location
3. Lower the sensitivity until you can barely hear the signal, this way you're somewhat simulating the very extreme edge of detection depth
4. Sweep the coil to make sure you can still hear the target
5. Note how much forward/backward coil shift is required for the target to completely disappear.

Depending on the soil, YMMV – some soils act as diffusers, so instead of defined "brush" pattern you get more of a "spray paint" pattern… but even then, at extreme depths the result of №5 will be many times smaller than you apparently expect.

Was surprised until you pointed it out. Again its what was told to us all this time about the field of dd coils. Im not doubting you just curious if anyone else knows or had the same picture of everything like i did

 

[Tony-Ok]

SMF , I still get excellent results with my 19 year old CZ 70. I know many say the dug lots of deep IRON. I was always able to not dig that deep iron / co- located to good stuff , 7”-10” by how I used the pinpoint button. Yes it is heavier than new detectors .I am currently working with the Nokta Legend. It’s lighter and has lots of great audio that I couldn’t get from an XP ORX .I do think the Legend will really be my new Go-To detector as soon as they get the 5.5”x9” coil available. I think most important advice I could give about NEW detectors is take the time and really learn the detector. HH Tony

 

[DigDog]

Search coil Electro-Magnetic Fields; Coverage-at-Depth; Overlapping; Effective Coverage.

Perhaps one of the most misunderstood and errantly described is the generated EMF and the shape of the responsive portion of that field as the coil-to-target distance increases (aka Depth).

A Concentric coil does not send out a 'V' shaped signal and a DD coil does not send out a 'knife-blade' signal that only goes straight down.

There is an EMF that is generated or projected around the Transmit coil and as the coil-to- target distance increases the [u']reactive'[/u] or 'functional' portion of that EMF will diminish and that means a target, especially a smaller target like a coin, will finally be responsive about in-line with the center-axis of the search coil. Doesn't matter if it us a DD or Concentric design.

That is why most skilled and avid detector users can Pinpoint most targets in-line with the center of the coil. It is the hot or most sensitive area.

Therefore, and I demonstrated this to a few groups years ago, if you want to find the deepest coins in a trash-free area, you should sweep left and right over the ground and advance the coil no more than the diameter of the coin you are searching for. In a wide-open park for example, it takes a lot of patience and a lot of time to tediouslhy cover an area to get all the good targets.

Most do not hunt that way which is why we can continue to find keepers in the middle of those wide-open spaces.

Monte

Same as pulltaboo pointed out I learned something new today. I always assumed because of marketing tools, diagrams that the field was as you said incorrect, that the concentric coil had a V shape in the ground and the dd a “knife blade” shape in the ground.
Thinking the dd coil coverage was more broad and even having a more deep coverage area vs just the point of a V on a concentric coil.
So to clarify is there any difference between the dd and concentric at all at the deepest point?
Is one even slightly broader or covers more or are they pretty much identical in the field of coverage with same size coils,

 

[DigDog]

SMF , I still get excellent results with my 19 year old CZ 70. I know many say the dug lots of deep IRON. I was always able to not dig that deep iron / co- located to good stuff , 7”-10” by how I used the pinpoint button. Yes it is heavier than new detectors .I am currently working with the Nokta Legend. It’s lighter and has lots of great audio that I couldn’t get from an XP ORX .I do think the Legend will really be my new Go-To detector as soon as they get the 5.5”x9” coil available. I think most important advice I could give about NEW detectors is take the time and really learn the detector. HH Tony

I have the 11” and 6” coil for legend and really looking forward to a 6x9 similar.
6x9 was always a favorite size to me.
Not sure if it would make a difference already having the 11 and 6 but be a nice in between that would probably serve most purposes better rather than switching coils freq

 

[DigDog]

Search coil Electro-Magnetic Fields; Coverage-at-Depth; Overlapping; Effective Coverage.

Perhaps one of the most misunderstood and errantly described is the generated EMF and the shape of the responsive portion of that field as the coil-to-target distance increases (aka Depth).

A Concentric coil does not send out a 'V' shaped signal and a DD coil does not send out a 'knife-blade' signal that only goes straight down.

There is an EMF that is generated or projected around the Transmit coil and as the coil-to- target distance increases the [u']reactive'[/u] or 'functional' portion of that EMF will diminish and that means a target, especially a smaller target like a coin, will finally be responsive about in-line with the center-axis of the search coil. Doesn't matter if it us a DD or Concentric design.

That is why most skilled and avid detector users can Pinpoint most targets in-line with the center of the coil. It is the hot or most sensitive area.

Therefore, and I demonstrated this to a few groups years ago, if you want to find the deepest coins in a trash-free area, you should sweep left and right over the ground and advance the coil no more than the diameter of the coin you are searching for. In a wide-open park for example, it takes a lot of patience and a lot of time to tediouslhy cover an area to get all the good targets.

Most do not hunt that way which is why we can continue to find keepers in the middle of those wide-open spaces.

Monte

As you say most don’t hunt that way, too much area and not enough time.
I think now thats why stuff is probably missed often then found later by someone else or a different detectors.
It comes down to having the right part of the coil exactly over the target and there is just way too much ground to go over everything just right so it’s basically hit or miss.
Gives a lot of hope to those areas you think are hunted out

 

[Tony-Ok]

As you say most don’t hunt that way, too much area and not enough time.
I think now thats why stuff is probably missed often then found later by someone else or a different detectors.
It comes down to having the right part of the coil exactly over the target and there is just way too much ground to go over everything just right so it’s basically hit or miss.
Gives a lot of hope to those areas you think are hunted out

Yes , concentric coils with the v shape coverage, if not overlapping the sweep carefully can result in missed targets. DD coil seems to allow you be less precise. But you can certainly get in close to trash if your recovery speed is fast . What I love about this hobby is I never stop learning new ways to apply my tools, and the good people who are willing to share their knowledge and experience with others !!

 

[pulltaboo]

It comes down to having the right part of the coil exactly over the target and there is just way too much ground to go over everything just right so it’s basically hit or miss.

Think of it this way: when you're using a regular overlapping pattern, you detect pretty much all shallower targets up to 1/2-2/3 of the maximum depth. In most cases that's more than enough.
However, if you find a (usually small) spot of extreme interest and it has a potential for very deep targets, start overlapping a lot (overlap 11" as if it was 6", for example) and slow down. It's painfully slow, but can be very rewarding. An example of such a spot would be 10-15' radius around very old trees that were used for picnicking many generations ago… especially near old churches!

 

[DigDog]

Think of it this way: when you're using a regular overlapping pattern, you detect pretty much all shallower targets up to 1/2-2/3 of the maximum depth. In most cases that's more than enough.
However, if you find a (usually small) spot of extreme interest and it has a potential for very deep targets, start overlapping a lot (overlap 11" as if it was 6", for example) and slow down. It's painfully slow, but can be very rewarding. An example of such a spot would be 10-15' radius around very old trees that were used for picnicking many generations ago… especially near old churches!

Great helpful advice. Sometimes get caught up in covering as much ground as possible, but probably missing many targets in the process.
Finding more targets in a small area is more productive, working smarter not harder

 

[pulltaboo]

Great helpful advice. Sometimes get caught up in covering as much ground as possible, but probably missing many targets in the process.
Finding more targets in a small area is more productive, working smarter not harder

I pretty much never care about "covering as much ground as possible" on unfamiliar site. If I'm sweeping aimlessly, I'm looking for trash. At this stage, I don't care at all about overlapping, as humans tend to litter in dense clusters. Once I found such cluster, I check out the nature of that trash (for example, construction trash is a hard pass in most cases). If it's promising, I slow down and start overlapping. If the trash is extremely dense (for example, pulltabs around picnic tables), I tone break it out and start looking for high conductive coins (VDI 40+). Once I find the spot where people drop a lot of coins, I change to my normal hunting mode and start overlapping a lot. And dig pretty much all mid and high conductors until I stop getting coins every few feet.

 

[captnkirk]

Those i would consider pretty deep especially for a dime and penny. Could have easily been missed even by the same detector my point

Well, I know for a fact that's correct. I hunted those same areas every year for 40+ years.

 

[Monte]

At this stage, I don't care at all about overlapping, as humans tend to litter in dense clusters.

TRUE ... However they can lose anything anywhere which means efficient site coverage is important. If I find the trash clusters I will happily take my time and work them. But it is the random, incidental losses that could be anywhere I am after.

Monte

 

[pulltaboo]

TRUE ... However they can lose anything anywhere which means efficient site coverage is important. If I find the trash clusters I will happily take my time and work them. But it is the random, incidental losses that could be anywhere I am after.

Like many things in life, it boils down to time. If it's a virgin tot and I have enough time, I'll be gridding, not just overlapping. But if I've to cover many acres of hunted out beach in 2-3 hours, for example, I certainly will be, um, speedrunning. And looking for trash patterns. Watzit, a bobby pin? And another one right next to it? Slow the hell down and spiral out.

 

[DigDog]

TRUE ... However they can lose anything anywhere which means efficient site coverage is important. If I find the trash clusters I will happily take my time and work them. But it is the random, incidental losses that could be anywhere I am after.

Monte

Yeah especially gold jewelry, that usually doesn’t happen in clusters, definitely more of a random occurrence at any time. Unless its a pirate chest lol

 

[pulltaboo]

Yeah especially gold jewelry, that usually doesn’t happen in clusters, definitely more of a random occurrence at any time. Unless its a pirate chest lol

If you're limited on time and don't know the place very well, looking for trash and coin spills will help you find more jewelry.
Example 1. Hunted out lake beach. Not a chance for a deep find, only fresh drops. If foot and towel prints are hard or impossible to read, trash spills are your best indicator of recent activity. No need to look for coin spills, although if you found one, it's a good idea to spiral out with lots of overlap.
Example 2. Picnic area polluted with tons of pulltabs, there's a pulltab every few inches. If you're limited on time, look for coin spills. Many people flick pulltabs as far as they can, making a sport out of it, while coins tend to fall on their own, marking the spot where people actually congregate and/or reach into their pockets.
Example 3. Mildly trashy large old site. There was a gazebo 100+ years ago, but the landowners are not quite sure where… Start looking for deep high conductors only, they'll tel you where that gazebo was.

 

[Nauti]

Currently I own about 9 detectors, give or take one or two. Two are SMF, an Apex and an EQ-800. At times I find they handle a site better in a selected Single-Frequency. My others are Singles, and since there is no such thing as a 'perfect' detector I determined long ago that having more than one detector on-hand provided me more versatilety and therefore results. Since the late '70s and to the latter '80s I used a lot of detectors in over a dozen US states and ground conditions, and in a variety of site challenges. I determined that for me the best overall operating frequency was from 10 kHz to 15 kHz.

I enjoy the detectors I have acquired and grab different units and mounted coils
for the site I decide to hunt. However, I do own and use a favorite single detector I could rely on if I had to trim down to only one detector. This model has served me well in a lot of locations and rewarded my efforts quite well since late '97. But I still have my other units because I like them, they work well and are comfortable to use.

If I didn't like them, they wouldn't be around.

Monte

I have had most success here in the UK within the range of frequencies you described.........my most productive machines have all run at 14khz.I don't know why this is but 14khz seems to do very well over here in UK conditions finding both deep targets and very small silver hammered coins.14khz seems to be a very good all round frequency that has served me very well over the years.

 

[DigDog]

I have had most success here in the UK within the range of frequencies you described.........my most productive machines have all run at 14khz.I don't know why this is but 14khz seems to do very well over here in UK conditions finding both deep targets and very small silver hammered coins.14khz seems to be a very good all round frequency that has served me very well over the years.

Nauti thats one of the reasons Tesoro cibola and vaquero were some of my favorite machines. Along with being simple and light they ran on the 14 KH z
Frequency. They did very well here also.
Imo and im no expert i think that frequency range is a good general range fir a variety of things and maybe why Tesoro used it. The Tejon they had ran on 17 KHz not far off and they did great on both silver and jewelry.
Nice thing about some of the smf like the Legend is you can choose the frequency and they have 15KHz which is right there in that range. Again im no expert but just from wht I gathered seems a good middle of the road . Some might argue, i think Monte who is an expert I believe said 10 or 12 can’t remember which is a good middle ground.
There are apparently advantages and disadvantages of different frequencies like really low 4KHz is deep and good with higher conductive targets and on the other end say 40KHz is not very deep but more sensitive to very small non conducive.
I could be wrong and someone correct me.
Again having a machine with the array of frequencies to choose from say 5 is like having 5 different detectors in one. Not to mention running some simultaneously.
I don’t work for any manufacturer or have any vested interests. Unless there are things im just not realizing i dont see the advantage of a older single vlf or even multi frequency without the option to choose just one at this point. When you have the option of having both in one.
Certain things aside of course. If you strictly hunt the beach and especially underwater the excalliber II is strictly a beach machine and hard to beat as is a PI machine, same if you are strictly prospecting in the desert for gold.
There are specialized machines that are really limited to certain areas. But for a general all around going to the beach then to the park then to prospect and not being able to spend multiple thousands on multiple machines some of these new detectors are hard to beat

 

[Monte]

I have:
2 favorite Tesoro's at 10 kHz each.

1 Fisher F-75+ at 13 kHz.

1 Garrett Apex which is SMF but I like to use 10 kHz and 15 kHz.

1 Makro Racer at 14 kHz.

1 Makro Racer 2 at 14 kHz.

1 Minelab Equinox 800 that is SMF but also offers 10 kHz and 15 kHz.

And to complement them a Bounty Hunter Time Ranger Pro and Fisher F-19 Ltd. That are each at 19 k0Hz and a Nokta FORS Relic also at 19 kHz.

As I have posted before, when design engineer George Payne designed the Discovery ztreasure Baron he selected 12.5 kHz and exlplained that it was a frequency that was good for low-conductors to high-conductors which made it good for US 5-Cent "Nickels" and gold jewelry on up to silver jewelry and copper and silver coins.

I had been using 15 kHz since '77 and 10 to 12 kHz since July of '83 with great success. That 'ideal' 12.5 kHz is exactly half-way between 10 kHz and 15 kHz. The other way to look at it is 10 kHz and 15 kHz are only 2.5 kHz from that "ideal" all-around operating frequency. Might explain why units in that span operate so well.

Monte

 

[DigDog]

I have:
2 favorite Tesoro's at 10 kHz each.

1 Fisher F-75+ at 13 kHz.

1 Garrett Apex which is SMF but I like to use 10 kHz and 15 kHz.

1 Makro Racer at 14 kHz.

1 Makro Racer 2 at 14 kHz.

1 Minelab Equinox 800 that is SMF but also offers 10 kHz and 15 kHz.

And to complement them a Bounty Hunter Time Ranger Pro and Fisher F-19 Ltd. That are each at 19 k0Hz and a Nokta FORS Relic also at 19 kHz.

As I have posted before, when design engineer George Payne designed the Discovery ztreasure Baron he selected 12.5 kHz and exlplained that it was a frequency that was good for low-conductors to high-conductors which made it good for US 5-Cent "Nickels" and gold jewelry on up to silver jewelry and copper and silver coins.

I had been using 15 kHz since '77 and 10 to 12 kHz since July of '83 with great success. That 'ideal' 12.5 kHz is exactly half-way between 10 kHz and 15 kHz. The other way to look at it is 10 kHz and 15 kHz are only 2.5 kHz from that "ideal" all-around operating frequency. Might explain why units in that span operate so well.

Monte

Seems as if your fisher F-75 is the closest one to being in the middle

 

[Nauti]

I has a T2 that ran the same frequency........did well with that one too.

 

[Odanscoils]

The 17 & 28 frequency thing was Minelab marketing at work. All BBS/FBS models, from the first Sovereign to the CTX, use 3.125kHz and 25kHz. Here is the TX waveform:

View attachment 27553
You can see that 3kHz is dominant which is why they did so well on deep silver.

How are you pulling this signal off ?
Are you plugging into the machine ?
Using a dummy load ?