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Iron masking and the F-75

Z

ziphius

New member
I don't know how many of you read Tom Dankowski's musings on metal detecting, but the guy is pretty smart. He works for NASA. Check out some of the technical articles at his site. One of his posts deals with iron-masking of good targets and how to mitigate it by tweaking the settings and audio mode. I've tried it and my machine runs much smoother in an iron-infested site that I'm very familiar with, while allowing me to crank the sensitivity way higher.

http://www.dankowskidetectors.com/discussions/read.php?2,2251
 
Well, that link didn't work, so here is the text from the Dankowski site:

F-75 Peak Performance - Disc '6' & mandatory 'monotone' relic hunting justification

When the F-75 is placed on a Disc setting of '6' and 'monotone'; This set-up config allows (under MOST circumstances) the best iron see-thru ability..... in locating non-ferrous targets in areas that are loaded with ferrous (usually nails) environments. The older the site....... the more nails will be present; subsequently, the more good targets will be masked. Most detectors will 'shut-down' under these scenarios. The F-75 (& T-2) are the only detectors currently available on the market that begins to tackle this type of (extremely common) scenario.... with some 'unmasking' success.

.... With F-75 Disc on '6' and 'monotone',,,,,,.....,,,,,, the moment you invoke a different tone option; Say 2-tone, 3-tone, 4-tone, etc.... the
 
What about all metal mode. I understand what your saying about disc.. But I think all metal is better. You just have to watch your VDI numbers. Is this setting in disc. the same as all metal? I've tried locating targets and switching back and forth to see the difference. And I still believe all metal is better. It does'nt lie. Every target I've dug in all metal is on the money by the scale. In disc. it is'nt. Unless the ground is highly mineralized. But it will still be a jumpy signal into the higher range. What's everyone else doing. I think this is a great subject on the F75!!!!
 
I recently started hunting a camp I've hunted for years and about gave up on. I'm digging some deep bullets (9-10 inches deep) that just sound "good". At that depth they won't even read on the VDI. The screen is blank. In disc. mode, they usually only gove a slight iron "tick". Absolutely not a disc. signal I would consider digging. All metal is great, if the area isn't too invested with nails, etc. The all metal is scarey deep. Bullets, etc. that are a little shallower, the ID is right on the money. The area I hunt only has mild mineralization. GB readings are gerally in the mid 50's. I haven't tried the mono tone with disc. set a 6, but will give it a try sometime. An interesting approadh to trashy areas.

keep on diggin'

jimmyk in MIssouri
 
It does work...mono tone disc at 6. All metal is great but you have to deal with the noise if you are in ground that is full of little trash. Even in mono tone you have to keep checking out the ID but it is worth it when you know you are in old area and you are relic hunting. How did Nasa Tom figure it all out he is a smart guy those Nasa guys are great
 
I'll preface this by stating, as a COIN SHOOTER, I use NASA Tom's 6 disc., 1 tone settings, a lot. But, mainly for cleaning up a site. "Cleaning up" being, endeavoring to get those coin targets masked by trash that I, or others, missed previously.

First off, I usually let the age and type of site (is it heavily trash ladden) dictate my settings. I use disc. 6 and 3h and 4h tones a lot. 3h on 40- 60 era sites and 4h on 30 and older era sites. 4h for those that have the potiential for IH's and other older coin varieties. I like 3h and 4h as the high tone right off alerts me to a potiential good coin target. Then, I check out the reading(s). Tone over all, though, is the final determination for digging. Yes, there is some falsing with using 3 and 4h tones, but by carefully investigating all high tones has resulted in my recovering nearly 200 silver coins this year from among the trash.

Being retired, I have the time to pound a old coin yielding site pretty hard. Once I have gleaned it, so to speak, then I go to mono tone and leave disc. at 6.

Since getting my F 75 in April of 07, I have played with every mode and setting combination on it and depending on the situation, all work great. The F 75, though, truly does excel on trashy sites and also gets near amazing depth.

As a side note, I NEVER USE NOTCH and usually only dig lock on 28, 29, 30 and 31 nickel readings that sound clean. Oh, a tab tail or small piece of can slaw does fool me and the 75 from time to time, but just by digging those readings alone I have recovered 7 gold rings, 25 Buffalo and 3 v nickels. 2 other gold rings and 2 v nickels were dug, but came in at different readings. HH jim tn
 
I'm not sure if this exact mode would work on the F-70, but there must be an equivalent setting. All-metal is also a favorite mode for me, but if there is a lot of iron, the constant sounds are fatiguing. I've tried almost all of the settings possible at a relic site I've hunted 40 times that has a lot of iron trash. The DISC = 6 and monotone setting is the one that results in the smoothest operation of the machine, while still allowing me to cherry-pick high conductors. This mode has also allowed me to crank the sensitivity all the way to 90 with continued smooth operation. This mode does require a bit of peeking at the VDI, but you can train yourself to listen for the 'smoother monotone' signals while you swing. When you get a target, don't look at the VDI, but try to guess what it is by the sound only. Then look and see how you did. In non-iron infested areas, I still prefer the DELTA PITCH mode, those high conductors are sweet to my ears! By the way, for those who didn't find Dankowski's website, here is the link:

http://www.dankowskidetectors.com/

The articles are entertaining and technical and the discussion forum is very good as well. - Jim
 
Well, it looks like this forum has some default where web links that end in dot com are automatically scrambled, no doubt to prevent commercial postings. You will just have to Google Tom Dankowski's name if you want the direct link to his website. Let's see if the Google site link, which I'm about to insert correctly into the brackets that follow, [www.google.com] gets scrambled in this message! Apologies to all for any inconvenience.

Jim
 
Oh Heck I just think it is time to dig every signal. Thats what i am gonna do next outing. See what i come up with.
 
Hello JK, my detecting time is very limited and have not used "all metal mode".
I would expect the good sounding signals (non ferrous) weather they are visible on the vdu or not to be strong and pinging and the ferrous to come in more of a low duller sound.
Is that the case?
Also what sort of vdu readings that can be seen do the good signals produce and what readings do the iron signals produce?
I will try all metal mode next time i am out over the holidays and any tips on ground balancing, settings, sounds to look out for would be much appreciated.
This is great thread.
Thanks, Mart.
 
Deeper bullets in all metal give a rounded, mellow tone that once you get used to is unmistakeable. Iron is more abrupt and harsh. Some deep nails will sound similar to bullets, but when you go at the signal one direction and turn 90 degress, if you get a double blip, it's a nail. Short, stubby, larger nails will fool you. Can't get around that. You ground balance in all metal just the same as in discrimination. Run sensitivity as high as you can. My ground balances in the mid 50's and I can run my sens at 90, even with power lines crossing my site. Once I get within 25 yards of the lines, I have to back off on sensitivity. Otherwise, I run it as hot as I can. You have to test each site to see how much power you can use. Deep bullets don't ID all that well in disc. If it sounds good in all metal and you get a blended sighal (iron and good signals on more than one pass), you have a good chance at being a bullet. As with anything, it takes practice. If you are in a camp and know there are (or used to be) relics, you have to go for the iffy signals. It just goes with the territory.

Hope that helps. Keep on diggin'

jimmyk in MIssouri
 
Thanks JK, i am in the UK so will give your advise a good try out and adapt it to our conditions.
Hopefully i should be at a dig this weekend and do some tests.

Take care. Mart.
 
I agree with JK.. I dug two small pistol bullets in the same hole at 16" and they were very very faint. They jumped from 15-45 and I thought they were iron but one thing I've learned about the bullets is. Once you get a hit stop and pin point the target. After your dead center of the target. X real fast over the target area and you'll get a true number id. If it's a minnie ball the target is a wider and broader sounding signal. Once you've dug a few you'll know if it's a minnie just by the target response. Also I've tried switching to disc. over these targets to see the response and some of the minnie balls that are 8" or deeper read as small iron. That's why I use all metal. But I haven't tried the monotone setting that Dankowoskis explaining. The next minnie ball I locate i'm going to switch to this setting and see what the response is. I think it will be promising as long as the soil is not highly mineralized. Can't wait to get digging. As far as I'm concerned the F-75 is the one and only BEAST!!!!!!!!
 
The mono tone and disc works for all relics and bullets even dating back to the early 1840s. We found buttons in iron trashed gound. You have to slow down and find the sweet on the coil and bam you pick it up right next to a square nail.
 
Speaking of bullets. This morning I located a williams cleaner. I was in all metal with the sensitivety at 99. It was close to nails and was reading 6 and jumping to 30. I knew it was a bullet just from the response. I tried switching to disc. with JE, sensitivety 99, monotone 2 and it just did sound off. I tried switching monotone to 4 and it was still iffy. The bullet was showing 8" in all metal and also in disc.. I still think all metal is the way to go. I know there's alot of you guys using disc.. But I think you're missing some of the deep targets. But like I said the F-75 is still the BEAST!!!!!!!!
 
All metql is absolutelyl the only way to go once you think you've cleaned out a spot with disc. The all metal will definetly read deeper targets than discrimination. At least that's the case in my ground, which is average mineralization. My reading is in the fid 50's. You can't rely on a VDI reading, either. My deepest bullets don't even register on the screen. They just sound good. If I do get a reading on the VDI, I haven't found it to be wrong yet. Can't say the same with discrimination.

keep on diggin'

jimmyk in Missouri
 
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