Exciting discovery

Now before anyone thinks about it, I'm not bashing any detectors, only making an example of how adjusting one machine might change how you think about adjusting another.

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.

Well stated. You changed settings...not for the detector; but/rather....... to better accentuate the 'human-factor'.

Now..................................... how many areas have we hunted ...and NOT used the correct site-specific setting!?

Good report Mark. ...............So, you used dp tones with the disc still set @ 15 ? Other settings were? Sens, mode? Thanks!

We have one room schoolhouses around here and just below the surface, is as you described.

The 75 did not do very well.....some wheat's about 40 or so yards away from the building.

Tom D. suggested I sick the CZ on the site, so I did with the 8" coil...... the cz got me a beaut of a Canadian large cent.

The ML-SE pulled some silver.

The ML-SE surprised me in coin mode,... I rarely use that much disc. I put it in coin mode and said to myself ' if there is a peep, I'm digging.....sure enough, 3 silver dimes in about 15 feet of swinging. This was years ago....hopefully my facts are straight, lol.

Excellent Info and reporting Mark!!

Keith

“I don't care that they stole my idea . . I care that they don't have any of their own”
-Nikola Tesla

Good write up. I like machines that you can adjust to the sites

Discrimination 0, sensitivity 85

Great use of dP audio, Mark.

I like that audio mode myself. You can 'hear' stability.

HH
Mike

Excellent post - I especially like your description of the analysis you did.

Rick Kempf
Gold Canyon AZ- where there is no gold