Rcpt Ack of F75 Ltd prototype

hi tom!
was wondering IF there is a 'set-up"
that exists on the "standard" f-75 with 5" dd coil ?
i am specifically referring to a setting,or (combination) of settings that could be utilized
that would be "close" to achieving a similar "resultant" to the 'boost"
process of the (l.t.d.) with 5" dd coil under the compacted soil scenario?..thanks!

j.t.

j.t. You can emulate the boost process F75's with 5" DD coils in every respect,,,,,, just not the extra depth capabilities that the 'boost process' presents on the LTD/SE-black. The advantage of the boost process is accentuated with the 5" coil on the LTD/SE.

hi tom!
ok! thanks! in your experience what would be the depth
difference approximately between the two platforms on say, a silver dime hunting in the same "site"
conditions ie: mineralization,compacted soil,moisture content,identical detector settings (except for "boost" process)..this is assuming
coil scrubbing over the surface of the site,and of course,the 5" dd coil being utilized?..thankyou!

regards!
j.t.

Very difficult question to answer....... due to many induced variables. I have been seeking this answer....... in scientific fashion........ for valid/solid data. ((Converting 'variables' to 'constants')). In general...... there is about a 1.0" gain in depth between a standard F75..... and a F75 LTD/SE in 'bp' mode.... when 5" DD coil is used. This holds true for nearly the entire spectrum of conductivity. . . . . from a Type-1 U.S. $1 gold coin...... to a silver dime.

On one particular day (with certain/standard atmospheric EMI conditions) I could set up a standard F75 at Sens '90'.......... and achieve identical performance characteristics to a F75 LTD (in 'bp' boost-process mode) at a Sens of 45. (((All other control panel config being identical))). This certainly makes it sound like the LTD is twice as powerful as the standard F75 (due to Sens '45' vs Sens '90'). But...... due to a non-linear scaling function...... this claim (and/or thought) is not scientifically founded. . . . . nor valid. However, there is a tremendous advantage between a standard 'pf' or 'de' setting on a F75 .......... vs the 'bp' setting on a LTD or SE-black. Usable and noticeable.
And......... as EMI conditions change from a normal/average day....... to low EMI conditions......... the gain between a boost process capable F75 (vs standard F75) becomes substantially more noticeable....... especially with the 5" DD coil. And this is for real dirt, real-world conditions. In real-world scenarios......... it certainly feels like double the performance. Dropping from a Disc setting of '5' to a Disc setting of '4' also accentuates/presents a fairly large performance (depth) gain.

One of the largest advantages the boost process units present........ is the simple fact that a large reduction in EMI is incurred ( "realized" ) when the 5" DD coil is utilized. This .... in turn ...... allows for a much higher Sens setting and more efficient use of the boost processes. On both a standard F75 and the F75 LTD/SE ..... there is a natural/automatic gain via reduced EMI by installing the 5" coil; yet, the boost process units can capitalize a greater amount (greater % ratio) of 'given' EMI reduction......... by using the newly given conditions... more efficiently.

When all is said-n-done.......... yes, there is a very usable gain (if hunting in carpets of nails and/or trashy areas) via the utilization of the 5" DD coil ........ even on a standard F75.

Something very difficult for me to say (and convey) ,,, yet,,, I hope it's in our future:
I would much rather hunt with a 5" DD coil equipped detector that can ascertain a dime at 14"......... vs ........ hunt with a 11" DD coil equipped detector that can only achieve 12" on a dime. To clarify my 'difficult to convey' thoughts: It may seem futile to hunt square-miles of property with a tiny 5" coil; yet, most folks would be 'shocked' at just how many targets would surface......come to light........ and how busy the headphones would be (giving plenty of targets to choose from)............. and how soon you would forget that you have a tiny coil installed at the end of the shaft .... giving that 'seemingly' useless/inefficient/tiny coil any merit of success...... and in the achievement of property coverage. To have a VERY "focused" tiny coil ((( not even imagined at current time ))) achieve tremendous depths......... in a very efficient fashion......... would be my 'future detector' dream. Taking a larger/standard size coil........ and driving it to greater depths....... is one thing.......... would 'light up' more targets; yet, would unknowingly mask even more targets. To take a tiny coil...........make it MUCH more 'focused' (narrower EM footprint) and drive it to greater depths............ takes on an entirely different 'extremely efficient' meaning........... once again.............. opening doors that most folks do not (yet) know exists. Again: How do you know what you are missing............ if you do not know it even exists.

Makes complete sense to me...very interesting post.

Question -- given the "electromagnetic detector" limitations you have spoken of many times (i.e. trying to find metal targets in an iron-mineralized ground matrix using electromagnetic detectors), and the resulting need for a "paradigm shift," as you have spoken of before, in order to achieve substantially more depth than we currently can with VLF units... do you feel that 14-ish inches on a dime could be achieved, theoretically, with tightly-focused 5" coil, on a VLF unit? Do you think this type of performance is still within the realm of possibility of what is capable within the EM paradigm?

Steve

There's a melting center where I take my silver & gold and they use a machine that analyses the exact content of gold, silver, and/or any other metal to the decimal. My question is, better than depth, with all the new computer technology integrated into these detectors why can they not create a detector that can analyse and "sense" when that exact metal composition (gold/silver) is under the coil? Mind you, this machine is a large box and a laser of some sort hovers over the metal it analyses and then registers to a computer.... I wish I knew what that exact technology was-- ill do more research on it tonight-- Tom you probly know what that machine is (and I'm sure it's thousands $$)

Just found it, it's called "X-Ray fluorescence analyser/spectrometer. Widely used for "elemental analysis".

As technology progresses....... I clearly remember running detctors in the 1970's on the ragged edge of detection...... and could acquire a dime to 6". I clearly remember running detectors in the 1980's on the ragged-overdriven 'edge'..... and could detect a dime to 8". Then...... around 1990....... running (current-day technology) on the ragged-edge...... and could acquire a 10" deep dime. Now........... since the early 1990's............ can run our newest technology on the ragged edge........ and can acquire a clad dime to 12".
I speculate the answer is 'yes'.

Interesting. Cool look back into history... Thanks!

Steve

NASA-Tom Wrote:
-------------------------------------------------------
> Very difficult question to answer....... due to
> many induced variables. I have been seeking this
> answer....... in scientific fashion........ for
> valid/solid data. ((Converting 'variables' to
> 'constants')). In general...... there is about a
> 1.0" gain in depth between a standard F75..... and
> a F75 LTD/SE in 'bp' mode.... when 5" DD coil is
> used. This holds true for nearly the entire
> spectrum of conductivity. . . . . from a Type-1
> U.S. $1 gold coin...... to a silver dime.
>
> On one particular day (with certain/standard
> atmospheric EMI conditions) I could set up a
> standard F75 at Sens '90'.......... and achieve
> identical performance characteristics to a F75 LTD
> (in 'bp' boost-process mode) at a Sens of 45.
> (((All other control panel config being
> identical))). This certainly makes it sound like
> the LTD is twice as powerful as the standard F75
> (due to Sens '45' vs Sens '90'). But...... due to
> a non-linear scaling function...... this claim
> (and/or thought) is not scientifically founded. .
> . . . nor valid. However, there is a tremendous
> advantage between a standard 'pf' or 'de' setting
> on a F75 .......... vs the 'bp' setting on a LTD
> or SE-black. Usable and noticeable.
> And......... as EMI conditions change from a
> normal/average day....... to low EMI
> conditions......... the gain between a boost
> process capable F75 (vs standard F75) becomes
> substantially more noticeable....... especially
> with the 5" DD coil. And this is for real dirt,
> real-world conditions. In real-world
> scenarios......... it certainly feels like double
> the performance. Dropping from a Disc setting of
> '5' to a Disc setting of '4' also
> accentuates/presents a fairly large performance
> (depth) gain.
>
> One of the largest advantages the boost process
> units present........ is the simple fact that a
> large reduction in EMI is incurred ( "realized" )
> when the 5" DD coil is utilized. This .... in turn
> ...... allows for a much higher Sens setting and
> more efficient use of the boost processes. On both
> a standard F75 and the F75 LTD/SE ..... there is a
> natural/automatic gain via reduced EMI by
> installing the 5" coil; yet, the boost process
> units can capitalize a greater amount (greater %
> ratio) of 'given' EMI reduction......... by using
> the newly given conditions... more efficiently.
>
> When all is said-n-done.......... yes, there is a
> very usable gain (if hunting in carpets of nails
> and/or trashy areas) via the utilization of the 5"
> DD coil ........ even on a standard F75.
>
> Something very difficult for me to say (and
> convey) ,,, yet,,, I hope it's in our future:
> I would much rather hunt with a 5" DD coil
> equipped detector that can ascertain a dime at
> 14"......... vs ........ hunt with a 11" DD coil
> equipped detector that can only achieve 12" on a
> dime. To clarify my 'difficult to convey'
> thoughts: It may seem futile to hunt square-miles
> of property with a tiny 5" coil; yet, most folks
> would be 'shocked' at just how many targets would
> surface......come to light........ and how busy
> the headphones would be (giving plenty of targets
> to choose from)............. and how soon you
> would forget that you have a tiny coil installed
> at the end of the shaft .... giving that
> 'seemingly' useless/inefficient/tiny coil any
> merit of success...... and in the achievement of
> property coverage. To have a VERY "focused" tiny
> coil ((( not even imagined at current time )))
> achieve tremendous depths......... in a very
> efficient fashion......... would be my 'future
> detector' dream. Taking a larger/standard size
> coil........ and driving it to greater
> depths....... is one thing.......... would 'light
> up' more targets; yet, would unknowingly mask even
> more targets. To take a tiny coil...........make
> it MUCH more 'focused' (narrower EM footprint) and
> drive it to greater depths............ takes on an
> entirely different 'extremely efficient'
> meaning........... once again..............
> opening doors that most folks do not (yet) know
> exists. Again: How do you know what you are
> missing............ if you do not know it even
> exists.


yes! understood,and i agree, because i always use my 5" dd coil in trashy sites,and
am able to understand exactly what you mean by NOT being concerned with coverage,and just concentrating
on listening to the targets the f-75 "lights up" just by overlapping sweeps in a small area! actually,it is quite exciting
because i have found a lot of good "hits" that i KNOW have been walked over! tom! i gotta tell ya,i DON'T take mine off
for all the attributes you cited. additional sensitivity,excellent depth,and outrageous separation. that little coil is really "crackers!'

j.t.

Tom, I don't know if this is a rediculous question:
What if you 'reversed' the modulated audio? So that you had a program the detector ran on in which small/deep targets registered the loudest, and large/and/or/shallow targets registered fainter. Is it technologically possible to program that?? If so, imagine the possibilities!

Just a question for our resident test-pilot.

How would an F75 react to this?



5 different conductivities, tone break or disc breakpoint set on the pulltab.



Coin masked 4 times by low conductor targets.

Will the lower conductors drag the ID down and prohibit the F75 from reporting the target.
Or will the F75 spit out a sharp high tone, telling you there is something above disc/tone break in the mix??

HH
Johnb

Tom you don't like my "reverse audio modulation" setting/option idea?? Imagine, scanning over a trash site-- all the surface bottle caps and pull tabs that scream out--QUIET Suddenly small deep targets are the ones screaming out! Especially on a chatty machine like F75-- you wouldn't miss a thing! I've gotta know if this is possible--I'm going to patent it!

I like it D-Tone. Be nice to be able to set the depth to where it is loud. In other words, set it at X inches, anything past that setting is loudest.

Small coils change everything..

Small powerful coils change it again...

On certain machine in my dirt I find the smaller coils punch better..

A Tejon with a 5.75 coil will punch deeper in some of my dirt than the stock coil ..

some of the guys I relic hunt with alway's ask why you running that small coil in the open area's...Try to explain the smaller footprint on a HOT coil see's deeper in the bad dirt..they Look at you like your crazy..but I have seen it too many times...A small powerful coil will punch better in certian situation's......

On the infinium P.I. I like the 8" better than the large coil....it see's deeper in my dirt...

Good write up Tom!!

Keith

You would hate reverse modulation. Aside from the fact that your brain would have a bit of a time rejecting the concept.......... the biggest problem would be: imagine all of the tiny/soft high-tone 'falses'....... now loudly blasting your brain!
In low mineralization Florida soil........... when the T2/F70/F75........ are at high Sens settings............ there is no audible difference between a 2" deep dime vs a 11" deep dime. The only clue that the target is deep is the depth bar-graph on the left side of the faceplate. ((( I never thought I used it very much at all...... until I put a piece of tape over it for a hunt. Had to pull the tape off in a matter of about 25 minutes. )))

A critical point to be made: On some detectors..... the modulated audio ramp-down is TOO rapid/excessive..... and too much reduction in overall audio. In a test-garden.... where you positively know a deep target exists........ a weak audio may be 'acceptable'. But.......... you may learn that..... in the real world..... that weak audio is about as loud as false chattering............,,,,,,,,,,,,,,,,................ subsequently, making the more important deeper targets........... undiscernable.

johnb........... that spring should be an eye-opener..... in front of a coil!

Indeed the spring does weird things when you wave it in front of a coil.

Double beeps, high tone falses,... completely disappearing altogether.
A while back I unnerved my detector dealer by waving a pretty big stainless hose clamp in front of a GMP 18 kHz.
The words : "This thing will find anything,... quickly were banished into oblivion,... jaw dropping experience!!"

Anyhow just curious if the F75 likes the non discriminated part of a signal or averages the complete signal and drops it a few ID's lower.

The wind is howling with sub zéro temperatures, so I banished myself to the warm and cozy detector shed once again.
Detecting in full winter gear isn't lots of fun, biggest problem is detectors with small buttons and free running knobs become a nuisance to use.
So I'm restricted to the heavy duty Excal II at the moment.

HH
Johnb

Now try that stainless steel hose clamp in front of many different brand detectors. (Yes, GMP is quite good at trying NOT to see iron/steel).

I have a fairly large open-ended steel spring......... without any of the loops shorting into each other (perfect helical wound) ........ that nearly all detectors will not detect. Very strange waving a large chunk of iron in front of a detector...... and it goes undetected. Eddy current/lines of flux defeated. Will induce fatal masking!

The hose clamp saw the entire XP range, even the "cheap and cheerfull" ADX models. Didn't register on any of the XP range, even the Deus.
So I guess cheap and chearfull or high €,$ models, they've got the same iron ignoring DNA.

HH
Johnb

If you want an example of a disappointing target response, this is quite good: I've been experimenting with search-coil construction, and among my bits I have a coil wound from 100 turns of 0.22mm diameter enamelled copper wire. The coil is around 50mm (2 inches) across, and the wire bundle is 5mm ( 3/16th inch) diameter. There's roughly 12 grams of pure copper in it, about a half-dollar weight. My F75 completely ignores it at any range. My feeling is it could have been ten times that weight and still given no response. In case you were wondering, the two wire ends were not connected.

Guys I'm sorry I know this is already listed somewhere on this forum, but what does the F75 (SE) smaller coil get (how deep) on a silver dime?
Thanks!!!
PS- Got a nice 54' rosey and 25' Greeney the other day in a CARPET of nails!! This is why I'm asking because I want to go back over it with the smaller but I want to make sure it's deep enough on silver dimes!!



Edited 1 time(s). Last edit at 03/12/2013 04:10AM by D-Tone.

bump

D-Tone......... With a fairly aggregate window of EMI conditions........... anywhere between 10.1" to 10.6" on a clad dime with 5" coil............. in Florida dirt.

Btt



Edited 2 time(s). Last edit at 01/27/2014 03:41AM by docbars.

Bump

Well worth re-mention: I keep having repeat experience(s) whereby the F75 LTD/SE (in boost process mode) with the 5" DD coil installed......... is having nearly parallel performance to the XP GMP with it's stock 9" DD coil installed. In some cases.... the 5" F75 LTD/SE is proving to be slightly deeper than the 9" GMP. Adjacent target separation is where the 'eye-opener' comes into the equation. With this large dramatic/differential/delta/difference between the 5" Fisher.... vs .... the 9" GMP .................... they both have "similar" adjacent target separation characteristics......... especially in carpets of nails. Major accolades goes to the large 9" coil on the GMP for adjacent target separation abilities. Major accolades goes to the small 5" coil on the F75 for exceptional/comparable depth performance in the same trashy environments. If only to combine the two accolades.

With the NEL 5" DD coil installed on the GMP...... a different world is opened. The adjacent target separation characteristics are far above the performance of (same physical dimension/size) 5" DD coil on the F75; yet, the 5" GMP's depth capabilities severely lack. (((Robbing Peter to pay Paul))). This commands/necessitates: Using the right tool....for the right job.

In any of the above cases, there are groups of targets whereby only ONE of the combination/configuration will detect that specific group of targets. Switching to a different group of targets......... and yet, only one DIFFERENT configuration/combination will detect this different group of targets.

Because this post is also heavily about the GMP............ if someone feels it could/should also be posted on the XP GMP Field Test thread......... you are encouraged to (cut-n-paste) do this!

Tom

From NASA Tom;

I have tried multiple times to figure out a way to impart/convey 'audio nuances // audio intelligence' .......... either in written words (for this forum) ....... or in captured video. It is too difficult. SOME written words/data can be conveyed; yet, not to the extent of bulk/aggregate level of understanding. I can say this about all metal mode:

1. The deeper the target, the weaker the audio response.
1a. The smaller the target, the weaker the audio response.
2. The smaller the target, the shorter the audio length duration.
3. The larger the target, the longer the audio length duration.
4. A round or spherical target will give a linear/consistent audio length duration while rotating your body around the target..... whilst continuously sweeping target.
5. A elongated (not round/not spherical) target will give a "varying in audio duration length" report as you rotate your body around the target.... whilst continuously sweeping target.
6. Once a target is located........ there is a (signal strength) linear audio ramp-down when you raise the coil at varying heights above the surface of the ground........ in direct proportion to mass/weight/size of detected target. (Experience/skillset required...... for intelligence gathering///target ID data collection).
7. With any brand detector that has a VDI/ID readout whilst in all metal mode....... the VDI numbers will vary in all metal mode.....as they will linearly vary in the ID/Disc mode. Yet, more confusion will ensue when multi-tones are introduced.
8. A Fe (ferrous) target will shift pinpoint location (change location) whilst rotating your body around the target........ especially the more elongated or odd-shaped the ferrous target. It is also common for a Fe target to give a double audio report.
9. A tiny fleck/flake of rust in close proximity of intended/detected target .... can throw all this data out the window.

This is only a 'start' of all metal audio training. It is too difficult to convey things like: A nickel 7" deep will report with a 196 milliSecond audio length duration...... with a certain/prescribed signal strength/amplitude. A piece of aluminum can slaw (also at 7" deep) the diameter of a nickel,,,, about the conductivity of a nickel..... but the thickness of a sheet of paper...... will report with a audio length duration of 189 milliSeconds...... and with a certain/prescribed signal strength/amplitude.
Another example = A nickel at 8" ............. vs ............. a lead BB at 1". Both have similar conductivities. How do you describe the linearity of signal strength ramp-down whilst starting to raise the coil to varying heights above the surface of the ground........ of either target. Amplitude, VCO, ID-bounce..... etc............

All Metal mode unique nuance audio intelligence is difficult to convey in words. . . . in all of its splended glory; yet, sooo much can be gained from it........ with the conclusive end-resultant being: a much wealthier/prideful lining in your pockets. Yes....... all of this data (in most forms) does convert/transition over to the Disc/ID side of the house.

NASA Tom



Edited 1 time(s). Last edit at 04/19/2014 03:43AM by ozzie.

More noteworthy/value-added documentum:

I have been detecting for over 4-1/2 years with a 'boost process' F75. Recently, I have encountered..... and only for the 7th time..... the ability to hunt with a Disc setting of '1'...... a Sens setting of '99'....... and 'bp' mode........ whereby..... there were NO EMI encountered. This is with the stock/standard 11" DD coil. My criterion: Coil stationary, 12" above the ground...... and parallel to earth. There must be a minimum of two frequencies (F1 - F7) that express zero audible EMI. Five of the seven times...... these (minimum of two) frequencies.... happened to be F3 and F6. When these conditions are met........... the abilities/capabilities of the F75 are unsurpassed. Depth on a clad dime (with reasonable ID) is just over 12"........... but........... can be detected beyond 14-1/2".... to nearly 15" (with a "iron" ID beyond 12" ).....Florida inert dirt. Yes......... anything beyond 12" ID's as iron.......... making it extremely difficult to have the willpower to dig tons of deep iron.....in hopes of a extremely deep non-ferrous target. BUT.......... this is the first step in achieving the next level of technological advancement. And............. if you are 'astute' with ferrous/non-ferrous differentiation........ (ie.... all-metal mode/style of hunting)..... you have a fighting chance for some success.
Also noteworthy: Six of the seven times I have encountered a "zero EMI" atmospheric hunting condition.......... I wished I could have had more Sensitivity to add. Only one of the seven times........ I knew that any additional Sens (if capabilities allowed) .... would have driven the unit into EMI status.

In summation: Seven times in nearly five years. This means: slightly more than once-a-year............ do I encounter the ability to run full throttle/full Sensitivity on this Indy 500 platform.

Moral Of The Story: Don't run this Indy 500 car wide-open-throttle in the city.

((( Future technology desire: Right now........ approx 1% of the sites allow full power (Sens) usage. Future desire = A platform that would allow 30% of sites to use full power/Sens ))). This depth ........... and the discoveries thereof....due to age............ are nothing short of 'stunning'.



Edited 1 time(s). Last edit at 04/22/2014 02:12AM by NASA-Tom.

Thread read....

Enjoying this F75SE post as well. A world of information that is amazing to say the least.

Thanks so much for the work and effort behind this.

Peter

Addition:
I decided to perform a crude one dimensional test between my Minelab SE in - Wide Open - Ferrous mode - 20 Sens
and a Tesoro Bandido all metal-1 disc- Just to see what the comparison would be like.... To say the least, it was an eye opener and exactly states why I am seeking a new direction in searching in iron/trash infested sites.

Holding the coin in front of and behind the piece of iron, the Minelab did Not pick up the coin.
Tesoro hit it every time.
In nearly every situation, with varying degrees of separation between the iron piece and the coin, the Tesoro hit it nearly every time.
In all I was surprised at just how big a difference there was between both machines. The Minelab in this particular situation fell flat on it's face.



The 75SE with the 5" coil is on my soon to purchase radar if I can't get a hold of a Goldmaxx Power unit.

Now back to reading...



Edited 2 time(s). Last edit at 08/14/2014 04:10AM by SilverPeter.

Bump...

“Never approach a bull from the front, a horse from the rear or a fool from any direction.”