COMPILATION #2

F-75 – BETTERING YOUR PERFORMANCE & UNDERSTANDING



On the F-75 (and T-2) .... by invoking the '4H' tone option..... the unit will sound very similar (audibly) to the 4-tones of a CZ-3D/CZ-70. And ONLY in this 4/4H mode ... it will then perform in a very similar fashion to the CZ-3D in respect to ..... specifically; "OLD COINS" with one small exception. Many folks are "old coins" hunters; and the 4/4H tone option is specifically targeted to aid them in the recovery of old coins that would otherwise audibly report as a trash tone (mid-tone). By invoking/selecting the 4-tone option (or 4H) some unique things happen. The following is a INCOMPLETE list of coins that will (now) ID audibly as the 3rd highest tone (a separate tone that is just below the highest tone the F-75/T-2 produces):

Many silver Half-Dimes
All silver 3-Cent Trimes
Many 'tilted' silver dimes & quarters and copper coins
Many 'partially masked' silver & copper coins
All Indian Head pennies
All Flying Eagle Cents
Many Half Cents
All U.S. $5.00 gold Half-Eagle pieces
Many coins 'on edge'
Many tokens

All of these items will audibly ID as a mid-tone (trash tone… just like aluminum trash) if 3 or 3H tone option is invoked. By invoking 4 or 4H…… all of these aforementioned targets will audibly report HIGHER than a mid-tone……. sounding almost as high as the high-tone…….yet MOST of the aluminum trash will still report as a mid-tone/trash-tone whilst in 4 or 4H tone option. As far as the ‘small exception’ in reference to the CZ-3D…… all of the aforementioned targets will ID as the highest tone on the 3D as long as the ‘Enhance’ mode is invoked, with most aluminum trash still reporting as a mid-tone/trash-tone. The conductivity of yesteryears coins are different as compared to modern coinage; hence the 4/4H tone option on the F-75/T-2 and the ‘Enhance’ mode on the CZ-3D. To date, all other manufacturers detectors do NOT have this option.

On the F-75 (and T-2), the VDI, audio tone-ID, and Disc are completely independent of each other. If anything, the audio ID vs. the Disc setting more closely parallel each other, yet still differ. This electronic design architect is deliberate..... and is a attribute that you will witness as you accrue some field experience.

Try this experiment, time permitting….. in a few different locations (different dirt scenario/resultants). Place Disc on a setting of '0' (zero). Find/detect a few different old-generation nails in their natural dirt setting. You will see them ID as say: '10' & '13' & '11'. Now..... place Disc on '7' and watch them completely disappear!!!..... both audibly and VDI.


__Another case-in-point --- recent experience/example;
I had been detecting a parcel of land in Sanford, FL for nearly 2 years with the F-75. For very specific testing reasons, I have always kept the Disc on a setting of '10' for this specific site ONLY. (Normally, I run Disc on ‘6’ or lower). This parcel of property was moderately heavy with iron trash. I removed ALL non-ferrous targets out of this area with F-75..... to the best of my (and F-75's) ability at a Disc setting of ‘10’. -----Now...... my testing would ensue. I now (finally) dropped Disc to a setting of '6' ((( been waiting to do this for a LONG time ))). MANY more non-ferrous targets came to light. The most noteworthy educational target was a fairly worn 1963 silver Roosevelt dime at a measured 6" depth. Out of the ground...... It ID'd as a continous '70'. In the ground, it ID'd as a 'bouncer'........ VDI jumping from 46 to 97 AND DEPTH WAS READING 11". In 'monotone', the audio was fairly clean and solid. Invoking 4H tones.... and the target audibly ID'd as a moderately solid/somewhat repeatable 3rd highest 'zinc' tone (what would be catagorized as CZ-70 'relic' tone). If I put the F-75 into 3 or 3H tone option..... the dime would ID as a mid-tone/aluminum soda-tab trash tone. This is somewhat unimportant....and not nearly as important as the following info.... prior to recovery:
When I first detected this target (1963 silver dime)..... First, I was surprised that I had missed this specific non-ferrous target (and many other non-ferrous targets). Second, BEFORE I even thought of digging this target...... I flipped the Discrim back to '10' and found my primary answer. The dime completely disappeared. NO audio response.....and no VDI. Dropping the Disc down to '6' again...... and the silver dime NOW was bouncing again on the VDI between 46 to 97. How and Why would this VDI 46-to-97 non-ferrous target be Disc'd out at a Disc setting of '10' ???? When I first attempted recovery of this target, I dug a 8" x 8" x 8" cube of soil/plug. I pulled the plug out of the ground and flipped it over. Because the target was reading 11" deep.... I had some certainty that the 8"-cube plug did not contain the target; subsequently resulting in my 'dunking' the coil down to the bottom of the hole....... only to find no target. Then I swept the coil over the up-side-down plug I just pulled from the ground...... and found the target only 2" deep from the bottom side of the plug (6” deep from the grass-side of the plug). I scraped away the dirt until I found a silver dime..... and could see the impression of the dime in the dirt at the 6" depth strata. The F-75 was completely wrong on the ID and also completely wrong on the 11" depth reading. Hmmmmmmm. Not happy and needing definitive resolution acquisition....."WHY" this happened. I proceeded to rapidly 'shave' the dirt plug from the bottom side... at approx 1/16" increments .... utilizing 20 lbs test monofilament fishing line until I found the answer; a blood spot in the soil (from a COMPLETELY decomposed small nail) at the 4" depth strata..... partially masking the dime. ........This validates the independence of VDI vs. audio ID vs. Disc setting. It also validates EM signal attenuation via the iron oxide blood spot..... and why the 6" deep dime registered as 11" deep. Good thing the dime was not an inch deeper (7" deep)...... or… the masking blood spot was not 1" shallower!
The F-75 was incorrect about ID and depth. That's okay..... as the Explorer completely 'nulled' over this target..... the Coin$trike was silently masked with no audio at all..... and the CZ was iron-falsing with high-tone/low-tone bounces.... very indicative of what 90-Deg. bent nails do to a CZ. The only detector that prompted me to dig this target…… was the F-75. It reported the most…… and was confused the least……….and……… the detector is not to blame, as there were ‘interference producing’ culprits under the coil. The least amount of filters utilized in the detector…. and lower Disc settings most always provide the best raw data and unmasking capabilities.

Many times, I have witnessed a non-ferrous target or coin (IH pennies, Ag dimes) report nothing at all (Disc'd out) with a Disc setting of '8' on the F-75 due to partial masking. Subsequently, dropping the Disc to '6'..... and these coins now suddenly VDI'd as severe VDI spectrum bouncers....bouncing between say; 11 all the way up to the high 90's. Other detectors would just simply report ‘iron’…. or remain completeley silent (silent masking).

Another somewhat similar phenomenon/example:
Say; you have a silver dime and a non-oxidized nail in very close proximity (nearly touching) at a handful of inches deep. The two targets are close enough to each other.... and laying in such a fashion so as to give you a VDI ID of...say; '13' (a higher ID than what most nails will ID….. but still within the ‘iron’ ID range). Let's say your F-75 Discrimination is on a setting of '6'.

1. If you are in '1' tone (monotone).... the F-75 will give you a good audio response to the target….. regardless of what the VDI is indicating. Since you are in 1-tone (monotone) there is no “tone-ID” per-se. (((You will most probably recover the target))).

2. Now….. say the F-75 is in 2-tone (or 3, 3H, 4, 4H tone options etc.....). And NOW......... the F-75 will respond with a ‘tone’ audio response that most detectorists will NOT dig/recover. The F-75 will report a 'iron' tone (the lowest sounding audio tone). The non-ferrous silver target will most likely NOT be recovered....... even though most all nails will discriminate out at a Disc setting of '6'.

THIS IS BECAUSE; When 2-tone (or 3, 3H, 4, 4H etc.....) is selected = ANY target that results in a VDI ID reading of '15' or below....will report as a 'iron' LOW-tone. Most folks will NOT recover iron tones……. Especially in nail infested areas.

Conclusively:
In situations like this..... COMPLETELY ignore the VDI. Rotate your body around the target until you have the best/most clear audio report. ((( This is usually best performed in monotone ))). NOW...... and only NOW,,,,, you may look at the VDI,,,, but for a distant secondary data input. You should already know (at this point) that you will/will not recover this target.

..... Also at this point, you may want to play with a interesting geophysics iron hysteresis, permiability and magnetism phenomenon; At the point of 'Max Q' audio resolution (where you acquire the cleanest/best audio response) on a partially masked target...... start rotating your body AWAY from this ‘Max Q’ point whilst sweeping coil from side-to-side, directly over the suspected good target……with your body encircling the target. You will notice that when you start rotating deeper into the iron masking culprit .... you will witness the VDI numbers climb very high,,,,, until you rotate far enough out of detectability of the non-ferrous target…. and too deep into the iron target. Audibly, the signal will sound very ratty....,,,,, just prior to complete loss of the non-ferrous 'good' target. Iron masking does weird things! USUALLY….. oxides of iron in close proximity of a non-ferrous target will cause the VDI to “up-average” on the non-ferrous target of interest….. and solid iron objects that are NOT rusted…… will cause a VDI “down-averaging” effect when a co-located non-ferrous & ferrous (coin & nail combo) is detected. BUT, since iron objects nearly always rust/oxidize……… you may have the solid iron object with all of it’s associated rust oxide… in concert with the non-ferrous target you wish to detect…….. presenting a wide array of resultants. The SIZE of the solid (remaining) iron object vs. the AMOUNT of surrounding oxides dictates the resultant.

NOW…… all of the above being said; Invoking a Disc of ‘0’ and a (required) multi-tone option of your choice (I prefer 4-tones)……. and hunting iron infested areas…….. if you can put up with all of the incredible iron-tone reporting audio fatigue, , , , your unmasking resultant can be phenomenal. Rightfully so; most folks cannot handle this incredibly audio fatiguing set-up; hence, my lack of ‘focus’ on this style/type of hunting. This is a whole different chapter (at some later time)……. and is for you to discover! ((( Most folks can handle a Monotone & Disc ‘6’ setting which causes most nails to ‘snap, crackle, pop’….. and any audio report that has ‘audio length’ to it…. a elongated audio report……. is worth investigating ))).


SUMMATION/CONCLUSION: Severely Fe masked coins and other non-ferrous targets can do VERY weird things to the detector (especially ID circuitry)...... and USUALLY..... MOSTLY in the fashion of VDI "UP-AVERAGING" (but never a guarantee)! -Welcome to the world of infinate variables!!!



Happy Intelligent Hunting,

Thomas J. Dankowski

Great Info Tom from what I have read in this post and your last one. Mono tone disc 6 or multy tone and disc of 0 and you have the best chance to find masked coins!

LowBoy

TAKE A LITTLE TIME KICKBACK AND WATCH SOME OF MY DETECTING VIDEO'S BELOW ON YouTube

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If you don’t dig it, then how are you going to know what you’re missing!
How can you have your pudding if you don’t eat your meat!

Tom,
Good report. 4H is how I use my F-70 also.
Tony

Yes, nearly all of this stuff applies to the F-70 also.

Fantastic compilation #2

Glad this helped.

Tom I almost always run my F70 at 6 disc, sens & thresh depends on the location/stability, but I've been running 3H tones until yesterday when I tried 4H tones for the first time. 4H tones should effectively give me more audio clues independent of the VDI. While I was out yesterday hunting I got a lot of bouncers into the 90's, not well repeatable, but after reading your analysis today it appears that I should dig any semi-repeatable 90# VDI bouncers.

What I've been doing is to switch to AT/AM mode and if it drops in iron range (usually around 11-12) I move on. With the 11" DD on the F70 if I get a jumpy #, and switch to AT/AM and it bounces from low iron to high coins, it's often a bottle cap (which I believe the F70 is somewhat correctly reporting the varied metal composition).

hh,
Brian

Brian,

Yes, this is true. The composition of a bottle cap is a ferromagnetic inner core. The exterior coating (of which the eddie-currents primarily generate) can be a tin/zinc coating..... a chrome plating..... a nickel plating,,,,,etc......... and this is what will confuse MOST detectors.,.,.,. especially the elliptical DD equipped units.

KEEP IN MIND; A co-locate coin & nail combo...... will present these bouncing VDI's.....including into the 90's....... regardless of ID or AM mode!

Tom

Thanks Tom. I'll dig some of the bouncing 90's on my next trip out to see what I might be missing. In trashy parks the F70 seems pretty bouncy as a rule of thumb, but if the #'s look interesting (coin area) I usually dig them, and more often then not find something good (at least clad).

Where I'm falling short is in getting depth out of the F70, I seem to be stuck at 6" or less, although I know it's capable of much more (and air tests at much more then 6"). Any tricks to finding the deepies? These guys with their Explorers are kicking my behind.

hh,
Brian

The F75 is bouncy also but you learn what to dig the number you want to dig will repeat on my machine as the machine runs the VDI numbers so look for repeats

LowBoy

TAKE A LITTLE TIME KICKBACK AND WATCH SOME OF MY DETECTING VIDEO'S BELOW ON YouTube

[www.youtube.com]

If you don’t dig it, then how are you going to know what you’re missing!
How can you have your pudding if you don’t eat your meat!

The deepies are the ones that bounce all over the board..... IRT the VDI. Especially in difficult ground.... or from partial masking.

But would give a constant audio response (high tone etc.), correct?


NASA-Tom Wrote:
-------------------------------------------------------
> The deepies are the ones that bounce all over the
> board..... IRT the VDI. Especially in difficult
> ground.... or from partial masking.

The audio will be a bit more 'stable' vs. the VDI; however, the audio presentation can also be jumpy..... especially with targets that are quite deep.

Bringing to front......per request.

bump

Bump

I have also found that rotating away from the "max Q" as Tom calls it can have a big effect on the Audio/VDI in a good way especially with elliptical coils. I feel it has to do with the orientation of the iron to non-ferrous target in relation to the sweet spot of the coil. In other words, minimum response to the ferrous plus max response to the non-ferrous.

It is very evident on the X-Terra 705 with a 5x10 coil.

Tom

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Edited 1 time(s). Last edit at 05/30/2017 09:33AM by Jackpine.

good article Tom D. Thanx.

Thank you Mr D -

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