REVIER
Well-known member
Saw this great post I will copy and paste below from another forum.
Really interesting use of DP on an F75.
I had to try this so I went to the entrance of my local park where I have spent hours and hours.
There can't be anything good left here...or can there, this is the perfect laboratory to find out.
This technique calls for DP tones and listening for very short blips, much shorter than I have been digging.
He knocks out all the iron at a disc setting of 15, I opted to lower it down to 6 so I can hear most of the iron.
I can control the thresh on the F770 in disc, -1 on that, any higher and it got way noisier...at these settings it was relatively quiet.
I used the big DD coil, sense was at about 75 and I turned boost on and off checking deeper targets.
Didn't really need the boost, all targets came in clear, even the deeper ones.
This was in black soil but still had a lot of minerals as the GB numbers were still in the mid 60's.
Did not notice the dirt bars but most of the time they are pegged around here.
As always there was still lots of extra iron, I dug several really rusty nails experimenting, got fooled by one or two when the numbers didn't drop lower but most I did see the drop and I dug them just to see if they really were iron...and they were.
On the bigger coin, a 1918 Canadian large cent that was a huge surprise since I live in the deep south, this thing was a really, really quick tone but I noticed, then I went back and manipulated the coil around the area attempting to get some repeating high numbers from two directions and I was successful.
Depth reading says 7" which is the right area for older stuff around here so I opened a hole.
This thing was sitting just about at that 7" level, when a quarter sized disc came up out of the hole I was thrilled.
Not a silver quarter, maybe a token?
So crusted over I had to rub hard just to get any details but eventually I saw the king's image on one side and part of the word Canadian on the other.
Eventually I got the date and this 99 year old coin made me smile.
The war nickel was a little tougher because I got some quick high numbers there too, (every coin comes in high here if it is past 3" or so due to up averaging around all this iron), but I also had drops down lower too.
Also showed 7" on the depth reading.
This was not as repeating as the cent but I decided to see what it was anyway.
After opening a hole I dug down a few inches and an old screw on cap from some sort of bottle came out, this probably caused the jumping, after that a few inches down a little deeper out came he nickel.
Parts looked silver so I was thinking war nickel but my soil can tend to crust over and hang on to targets so this is as good as it gets until I tumble it cleaner.
I got a 1945 date, saw the big P so that was good enough.
Got another 1962 nickel later, also about 6", a few other non ferrous targets like shell casings that I was happy to dig plus as I mentioned got fooled a few times by rusty iron but I am new at this method so I will get better.
It worked extremely well, anything good I get out of this site is a huge victory,
Slow movements of the coil, listen for the good high tones or any tones that aren't iron even if they are super quick, check targets from two directions and look for repeatable behavior in DP tones.
In seems to unmask things pretty good in some pretty bad conditions.
Don't know if other tone settings are the same but those really short tones might only be really noticeable or more noticeable in DP.
A big thanks to markg for these settings.
-----------------------
markg
Re: Delta Pitch
February 25, 2017 06:27AM
A little background information before revealing what I’ve discovered about the Fisher F75. More than 10 years ago I started inquiring about some old locations I hunt. Most of the locations are old, shut down schools where coal was used as a heating source for decades. Before the EPA was birthed most people did whatever pleased them when it came to disposing of waste, regardless of what it was and these old school sites are no exception. The burnt coal waste was spread over many acres of school property which created some extremely harsh ground conditions. Grass and weeds find it hard to get a start and most areas are void of any vegetation. Most of the school grounds look like Martian landscapes with small BB size or smaller pieces of coal waste everywhere. This material attracts to a magnet with little effort and can reduce depth of all VLF detectors by well over half. In fact until recently maximum detection depth was actually 2-3”, any target deeper would give a solid iron audio report if any sound at all. After many years of hunting these areas all but completely unsuccessfully I finally purchase a White’s TDI SL.
It turned out the SL opened up these old sites and many nice coins and relics were unearthed, but not without many trials and numerous adjustments. Case in point: one particular area had been, in my opinion hunted out with many different VLF machines over a 10 year period and I was certain there were no good targets left. I had been hunting about 15 minutes and all the SL was giving were very short audio reports, which sounded more like chatter or EMI and not targets. This prompted me to increase the time delay to about 15 “which increases the time before a transmitted signal is analyzed” thinking the small pieces of coal waste were the short reports I was hearing. Continued hunting another 5 minutes and noticed the short audio chatter continued but not to the same magnitude. Stopping and increased the delay to around 17 and off I went hunting again. Suddenly I noticed the machine was running very quiet, to quiet. A minute or two later and a very loud low tone, which on the SL means a high conductor, I stopped and reduced the delay to 10 and found my definite answer. The coal waste was causing all the ground chatter and false audio reports. Increased the delay to 17 and recovered a wheat penny around 4” deep. Now to be honest I had to stop for a moment and think about what just happened. Decided to start over I returned to where I began hunting and discovered I had passed right over many good targets. After digging a few more wheat’s I decided to start checking these targets before digging and discovered if I decreased the delay most of these targets became the short sounding audio reports I had heard earlier. The PI was just the trick to discovering some nice coins deeper than 4” in these barren areas. I must add the SL is not the best choice to make if there is an over abundance of nails because of the very limited discrimination capabilities of this particular machine. As a final note I must admit this machine has opened up a lot of hunted out harsh ground sites. Now on to the next story, but this time with my Deus and the Fisher F75 at a different location.
While hunting one day at a different location I noticed a lot of broken/clipped audio reports from the XP Deus in a particular area, and of course remembering the experience with the PI machine, I started adjusting as many different settings as I could think of and finally found that the full tone mode (only changed the audio function) provided the best of audio signals, dug some and found they were, indeed, good targets. At that point I was well pleased with the Deus, and after discovering this I continued to dig many more good targets. After a good bit of time I decided to break out the F75 and hunt the same area hunted with the Deus. Amazing to find there were still many more targets in this area, all giving extremely short, more like chatter audio reports, I started experimenting with the different settings on the F75. Sensitivity up and down brought no change in the audio. Finally going to my old faithful 1F with discrimination of 15 and some, only a very small percentage of the audio signals began to smooth out, but not enough to prompt me to dig. Not happy with the results I decided to try each process and nothing changed the signals. Then remembering the only changed needed on the Deus to detect similar targets was to change to full tone, but the F75 doesn’t have that choice, well I was kind of wrong. Changed to dP tones and wow it did just as good as the Deus, in fact the audio was slightly better, more smooth, cleaner start and finish of the audio signal. Interesting to say the least, so I decided to change and go through each of the process and found the dp tones was the setting that was necessary to hunt this area. Interesting note, my understanding of dp is it only changes the audio, has nothing to do with depth, sensitivity and discrimination, but I believe there is more to dp.
Really interesting use of DP on an F75.
I had to try this so I went to the entrance of my local park where I have spent hours and hours.
There can't be anything good left here...or can there, this is the perfect laboratory to find out.
This technique calls for DP tones and listening for very short blips, much shorter than I have been digging.
He knocks out all the iron at a disc setting of 15, I opted to lower it down to 6 so I can hear most of the iron.
I can control the thresh on the F770 in disc, -1 on that, any higher and it got way noisier...at these settings it was relatively quiet.
I used the big DD coil, sense was at about 75 and I turned boost on and off checking deeper targets.
Didn't really need the boost, all targets came in clear, even the deeper ones.
This was in black soil but still had a lot of minerals as the GB numbers were still in the mid 60's.
Did not notice the dirt bars but most of the time they are pegged around here.
As always there was still lots of extra iron, I dug several really rusty nails experimenting, got fooled by one or two when the numbers didn't drop lower but most I did see the drop and I dug them just to see if they really were iron...and they were.
On the bigger coin, a 1918 Canadian large cent that was a huge surprise since I live in the deep south, this thing was a really, really quick tone but I noticed, then I went back and manipulated the coil around the area attempting to get some repeating high numbers from two directions and I was successful.
Depth reading says 7" which is the right area for older stuff around here so I opened a hole.
This thing was sitting just about at that 7" level, when a quarter sized disc came up out of the hole I was thrilled.
Not a silver quarter, maybe a token?
So crusted over I had to rub hard just to get any details but eventually I saw the king's image on one side and part of the word Canadian on the other.
Eventually I got the date and this 99 year old coin made me smile.
The war nickel was a little tougher because I got some quick high numbers there too, (every coin comes in high here if it is past 3" or so due to up averaging around all this iron), but I also had drops down lower too.
Also showed 7" on the depth reading.
This was not as repeating as the cent but I decided to see what it was anyway.
After opening a hole I dug down a few inches and an old screw on cap from some sort of bottle came out, this probably caused the jumping, after that a few inches down a little deeper out came he nickel.
Parts looked silver so I was thinking war nickel but my soil can tend to crust over and hang on to targets so this is as good as it gets until I tumble it cleaner.
I got a 1945 date, saw the big P so that was good enough.
Got another 1962 nickel later, also about 6", a few other non ferrous targets like shell casings that I was happy to dig plus as I mentioned got fooled a few times by rusty iron but I am new at this method so I will get better.
It worked extremely well, anything good I get out of this site is a huge victory,
Slow movements of the coil, listen for the good high tones or any tones that aren't iron even if they are super quick, check targets from two directions and look for repeatable behavior in DP tones.
In seems to unmask things pretty good in some pretty bad conditions.
Don't know if other tone settings are the same but those really short tones might only be really noticeable or more noticeable in DP.
A big thanks to markg for these settings.
-----------------------
markg
Re: Delta Pitch
February 25, 2017 06:27AM
A little background information before revealing what I’ve discovered about the Fisher F75. More than 10 years ago I started inquiring about some old locations I hunt. Most of the locations are old, shut down schools where coal was used as a heating source for decades. Before the EPA was birthed most people did whatever pleased them when it came to disposing of waste, regardless of what it was and these old school sites are no exception. The burnt coal waste was spread over many acres of school property which created some extremely harsh ground conditions. Grass and weeds find it hard to get a start and most areas are void of any vegetation. Most of the school grounds look like Martian landscapes with small BB size or smaller pieces of coal waste everywhere. This material attracts to a magnet with little effort and can reduce depth of all VLF detectors by well over half. In fact until recently maximum detection depth was actually 2-3”, any target deeper would give a solid iron audio report if any sound at all. After many years of hunting these areas all but completely unsuccessfully I finally purchase a White’s TDI SL.
It turned out the SL opened up these old sites and many nice coins and relics were unearthed, but not without many trials and numerous adjustments. Case in point: one particular area had been, in my opinion hunted out with many different VLF machines over a 10 year period and I was certain there were no good targets left. I had been hunting about 15 minutes and all the SL was giving were very short audio reports, which sounded more like chatter or EMI and not targets. This prompted me to increase the time delay to about 15 “which increases the time before a transmitted signal is analyzed” thinking the small pieces of coal waste were the short reports I was hearing. Continued hunting another 5 minutes and noticed the short audio chatter continued but not to the same magnitude. Stopping and increased the delay to around 17 and off I went hunting again. Suddenly I noticed the machine was running very quiet, to quiet. A minute or two later and a very loud low tone, which on the SL means a high conductor, I stopped and reduced the delay to 10 and found my definite answer. The coal waste was causing all the ground chatter and false audio reports. Increased the delay to 17 and recovered a wheat penny around 4” deep. Now to be honest I had to stop for a moment and think about what just happened. Decided to start over I returned to where I began hunting and discovered I had passed right over many good targets. After digging a few more wheat’s I decided to start checking these targets before digging and discovered if I decreased the delay most of these targets became the short sounding audio reports I had heard earlier. The PI was just the trick to discovering some nice coins deeper than 4” in these barren areas. I must add the SL is not the best choice to make if there is an over abundance of nails because of the very limited discrimination capabilities of this particular machine. As a final note I must admit this machine has opened up a lot of hunted out harsh ground sites. Now on to the next story, but this time with my Deus and the Fisher F75 at a different location.
While hunting one day at a different location I noticed a lot of broken/clipped audio reports from the XP Deus in a particular area, and of course remembering the experience with the PI machine, I started adjusting as many different settings as I could think of and finally found that the full tone mode (only changed the audio function) provided the best of audio signals, dug some and found they were, indeed, good targets. At that point I was well pleased with the Deus, and after discovering this I continued to dig many more good targets. After a good bit of time I decided to break out the F75 and hunt the same area hunted with the Deus. Amazing to find there were still many more targets in this area, all giving extremely short, more like chatter audio reports, I started experimenting with the different settings on the F75. Sensitivity up and down brought no change in the audio. Finally going to my old faithful 1F with discrimination of 15 and some, only a very small percentage of the audio signals began to smooth out, but not enough to prompt me to dig. Not happy with the results I decided to try each process and nothing changed the signals. Then remembering the only changed needed on the Deus to detect similar targets was to change to full tone, but the F75 doesn’t have that choice, well I was kind of wrong. Changed to dP tones and wow it did just as good as the Deus, in fact the audio was slightly better, more smooth, cleaner start and finish of the audio signal. Interesting to say the least, so I decided to change and go through each of the process and found the dp tones was the setting that was necessary to hunt this area. Interesting note, my understanding of dp is it only changes the audio, has nothing to do with depth, sensitivity and discrimination, but I believe there is more to dp.
