COMPILATION #1

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 ‘audio’ portion of the Disc, ....even though Disc is set on '6'...... will instantly become a Disc setting of '15'. What does this mean? = Any target that is between a Disc level of "6 thru 15" will now audibly report as a "Low Tone" (iron tone). BIG PROBLEM for a multiplicity of reasonings. Now, any target that is ABOVE a "15" (VDI reading)... MIGHT report a higher tone,,,, (tone freq depending on what tone option is invoked). -------Most folks do not dig iron. And most folks WILL miss masked non-ferrous targets when multitones are selected. Said differently via utilization of a "extremely common occurrence" example;

----- Recently, I recovered a badly masked Barber dime. When I (first) detected this severely handicapped dime, the F-75 was in 'monotone', Disc '6', 'PF' and Sens on '99'. In monotone, the dime AUDIBLY sounded good. (( I was going to dig this target )). The VDI was terrible - would/could NOT lock on to anything close to resembling a highly conductive piece of silver. I then invoked 2-tone..... leaving ALL other settings alone. Now.... the dime was constantly audibly reporting as low-tone (iron-tone).....even as I rotated my body around target. The VDI was jumping all over the board…. mostly in the iron ID range. I made the decision to NOT recover the target, primarily due to low iron-tone..... and walked away. Several hours later, I decided to go back and recover this target (and MANY other similar responding targets)..... with F-75 back in 'monotone'. Results = One 2" nail, two 1/2" long nails..... and one 1893 'O' Barber dime. Yep; MOSTLY iron, but certainly not ALL iron. The 2-tone mode did not lie. Justification = The composite of the 4 targets (3 nails & one dime) were higher in conductivity than any one of the nails individually...... but TOTAL conductive composite was HIGHER than any nail (or combination of nails) would have cumulatively registered. Because I (and the detector) knew that the detected target (suspected co-locate/composite of multiple targets under coil) were higher than the conductivity of most nails... yet STILL ID'd in the 'Fe/iron' range...... this target was needing recovery. Good thing! Selecting any other tone option..... and the detector would audibly report the composite as "low-tone/iron-tone". Yes, the F-75 will still unmask more non-ferrous targets than other detectors if 2-tone or multiple tones are selected; however, a substantially greater level of unmasking performance can be ascertained when unit is placed in 'monotone'. ((( The T-2 with a Disc setting of '21' is the exact same thing as all of the info above ))). Having the ability to adjust how MUCH iron you choose to discriminate….is a major attribute. Small iron items….. such as nails…… will Disc out at a fairly low iron Disc range.

This is Approx 10% of F-75's capabilities.

In addendum:

#1 On both the T-2 & F-75..... running a higher Sens gain in the trash (especially iron) presents a MUCH enhanced resolution on non-ferrous targets amongst iron. This is a paradoxical contradiction; what is....... but should NEVER be. Next time you find a non-ferrous target amongst high iron trash concentration (with high Sens settings)....... drop the Sens and see what happens. The non-ferrous target audio resolution will decrease.......possibly even disappear completely (depends how badly masked the non-Fe target is). The more masking... the HIGHER the Sens needs to be on the T-2/F-75. ((( This is not a typo )))!

#2 The mandatory "monotone" instructions is primarily for iron nail pits. Long description:
--- If a non-ferrous target is co-located in very close proximity to iron/multi-iron scenario.......,,,,,,,, then......... as you rotate your body around the composite target; the audio will be bouncing between all of the different tones (same with VDI)...with each tone being exceptionally short in duration. You may even encounter a multi-tone audible reporting in ONE sweep of the coil !!! ..... Surely enough to confuse most detectorists into a NON-recovery decision..... as the target is audibly confusing,,, and is not a 'clean' or "solid" repeatable sounding target. ((( Most masked targets are not 'clean' audio targets ))). Each of the multi-tones reporting will be audibly shorter in duration. Kind of a "ratty" sounding/bouncing signal. NOW..... when monotone is selected/invoked,,,,,, this SAME composite target(s) will audibly report a LONGER duration SINGLE-tone audible presentation (instead of several ‘shorter-in-length’ different tones in one sweep of the coil)..... that will less-likely confuse the operator ..... and authorize the operator to make a much better profiling of the composite target audio signature ..... with the end resultant being a more intelligible target-recovery decision from less audible fatigue. Tech Terms; A better signal-to-hull emitter correlation. I'd rather hear ONE "longer" monotone vs. several shorter multi-tones in rapid succession….in a single coil sweep. NOW....... IMAGINE sweeping the coil in a iron nail pit with 2 or 3 or ---- especially 4 tones selected. A hill-billy jug band!!! Try and make non-fatigued intelligent audio decisions under this common scenario! The VDI is extremely "jumpy" in iron pits.... AND SO WOULD BE THE MULTI-TONES!!! ...... At least,,,, in monotone,,,,, as the VDI is presenting extreme variances .... the one monotone will be CONSTANT and STABLE......even as the conductivity of the multi-target scenario varies dramatically ........ even with only one sweep of the coil.

#3 On CZ-3D.... in the 'enhanced' mode; Nearly ALL old coins.... and new coins,,,,, will report as "hi-tone". On the F-75 & T-2, you MUST invoke 4-tone...... which will then cause the OLD coins to audibly report in the 3rd highest tone region (vs. mid-tone)...... and the new coins will remain in THE highest tone. If you select 3-tone on T-2/F-75.... only the NEW coins will report as high-tone.... and SOME of the older coins might report as high tone. Most of the older coins would then audibly report as mid-tone (just like the alum soda tabs).

#4 If you run Disc on 0-4 on the F-75..... all nails will report as good targets in monotone. With F-75 Disc on '6'..... MOST (not all) nails will report as a snap-crackle-pop....tick-click (not a solid audio); which, in turn..... can be ignored. Axe heads, hammers, gun barrels and other large iron targets will give a good audio with Disc on '6' on the F-75. .... But, MOST fields we hunt are not loaded with axe heads, gun barrels and hammers.

#5 The F-75/T-2 have a tendency to "up-average" non-ferrous target ID numbers when near disintegrated iron or bad minerals. VERY common occurence. It is partial 'silent masking' coupled with conductive target response. I have several documented experiences exactly relating to this.
+++ Let's say that you detect a slightly masked silver dime. Normally (without being masked) it would VDI at '71'. But now..... it's slightly masked. It may now VDI at '89'..... a somewhat "up-averaging" VDI common resultant. In both cases, the detector reports "hi-tone". No problems yet.

A slightly corroded buffalo nickel will VDI at '28' in open air...and audibly report as a 'hi-tone'. Now....... with this same nickel in the dirt ... in a natural setting and partially masked..... IT TOO will "up-average" (just like the silver dime) ,,,, to,,, say = VDI '47'. Hmmmmmm, now the nickel 'looks' like a soda tab to the detector...and the unit will now report the slightly masked nickel as a mid-tone. ((( All of this holds true for medium conductivity items...such as relics & gold jewelry ))).
....If you are recovering Mercury dimes at (say) the 11" depth strata...... You may want to ALSO recover the 11" depth strata mid-tones.... as many of these will be the corresponding era Buffalo nickels.
The T-2 & F-75 electronic design architect is notorious for "Up-Averaging" non-ferrous targets in the presence of iron & iron oxides. Not a problem, considering other single freq units would remain completely silent.
ALL detectors have a difficult time ID'ing nickels. CZ's do the best ID job, but are not immune to EASILY mis-ID'ing nickels.

#6 All-Metal mode is the deepest mode; HOWEVER, coin-sized objects will still ID to depths of only 12" or so. The depth at which a target will properly ID in the ID mode..... is the same depth it will properly ID in the AM mode (F-75 & T-2). Yes, targets will audibly report to greater depths in the AM mode...... but the VDI screen will remain blank on the deeper targets. Now,,,,,,, that being said...... IF you are a extremely seasoned hunter...you can take advantage of these greater (no VDI) deeper depths. If you can audibly 'profile' deep/weak targets, you are in for some serious enjoyment. Can you tell the difference between a small target that is shallow, , , such as a lead .22 Short 29Gr rimfire projectile at 4" deep vs. a U.S. nickel at 12" depth. These are both non-ferrous targets. ....... And can you tell the difference between a 2-Penny nail at 7" vs. a Wheat penny at 12". This latter example... is the MOST common and MOST important test for the astute detectorist,,,, as it poses the greatest challenge with the most significant, rewarding resultant. Of note; Dinosaurs can be miles beneath the Earths surface. Egyptian sunken cities are dozens of feet deep........ thusly; the 100 year-old coins we wish to find are a foot or two deep.

NOW.......... that being said…. (((( If you are in a nail infested area, and you do NOTaudibly fatigue easily = = = )))) IF, IF, IF, you can handle a lot of noise.... and the detector can handle (not EMI plagued) a Disc setting of '0' and a Sens setting of '99'....then hunt in 2, 3, 4 tones (your choice),,, hunting for the "deepies". YES.....the detector will mask some targets in this audio selection config (ie 2, 3, 4 tones are selected) because any (heavily masked) target that VDI ID's as a '15' or below will present a 'iron' audio response (as so stated in example above),,,,, BUT, the trade-off is; the F-75 will go deeper just by virtue of the Disc setting being '4' or below (especially '0').

Soooooooo, I am saying (by this set-up config) = MORE MASKING, BUT GREATER DEPTH. Hmmmmmmmm... trade-off. Which one does better? Disc '6' & monotone???? or Disc '0' and multi-tone???? The answer is: They BOTH do!!!!!!!!!
I am saying; HUNT the area in Disc '6' & monotone...... and perform all of the 'unmasking' that you can. THEN hunt in Disc '0' and a tone-option of your choice.... going for all the deepies.
NO...... you can not have both at the same time.

In theory,,,,,,, in an ideal world; Targets are spaced far enough apart so as to be single, solo targets....... not tilted, not near hot rocks, not near iron, no dirt mineralization etc....... This would allow the detector to ID targets with greatest accuracy. HOWEVER; This is not reality ..... not the real world. Fact of the matter is; Nearly all targets are somewhat/somehow handicapped. First; as a good target (say a coin) is moved closer to any other metallic object, a multiplicity of problems are introduced to the detector. Now add dirt mineralization, tilt the coin, add a hot rock or two, etc..... WELCOME TO THE REAL WORLD! This is genuinely what we contend with as detectorists and detector engineers. How do you correct and compensate for infinite unpredictable variables?! Secondly; What may be categorized and classified as "these two targets are too close to each other" to Brand 'A' detector & coil Assy…. may present different results to Brand 'B' detector & coil Assy. The extremely enhanced adjacent target separation characteristics afforded by a elliptical Double D coil presents just exactly such. A coin and a pull-tab... both at a 6" depth....... and adjacently separated by 6", poses a severe problem to a 10.5" concentric coil,,,,, but does not even approach "problem" status to a 11" elliptical DD coil.


When absolute maximum overdriven performance is desired:

1) Starting point = Factory Preset and Ground Balance.

2) Hold coil parallel to ground.... and at a height (approx) 8" above the ground. Do not tilt the coil upward. Increase Sens to '99' and verify detector is audibly stable. This is the FIRST step. (((Shut down your intents if you cannot ascertain stability with Sens on '99'))).

3) Next....... IF no EMI is encountered with '99' Sens........ THEN you may start to bring Disc down. Start with Disc '6'.

4) IF the detector is still EMI stable.... see what happens to EMI stability.... by lowering Disc BELOW '5'. '5' is not the magic number.... but '4' is. Going to a Disc setting of '4' is where sensitivity receives yet another boost. (((And USUALLY............... when you are at a Disc of '4' ... and ESPECIALLY lower... is where multitone option is virtually required))). Set Disc on '4' and verify detector remains audibly stable.

5) Now, Drop Disc to '3'... then '2'... then '1'... then ultimately '0'….. verifying audio stability is still retained.

6) Now select JE mode and verify detector remains audibly quiet.
((( IF .... during any of these steps, the detector becomes audibly 'chattery' .... you have electrical interference (EMI).... and must back-up in procedure,,,,, until you re-find electrical stability,,,,......,,,,,,, and these are the settings you should hunt with ))).

7) Start sweeping the coil..... with the coil remaining 8" above the ground,,,, and verify detector remains audibly stable.

8) Start lowering the coil closer to the ground while continuing to sweep....and verify detector remains audibly stable. If you manage to get the coil all the way down onto the ground while sweeping..... and the detector is audibly stable,,,,, you are home-free!!!!... and have the most powerful relic detector currently on the market. Remember, many relics are very low conductors (in the 'foil' range).

((( IF..... while lowering the coil to the ground as you are sweeping,,,,, and the detector THEN becomes audibly unstable..... you have ground interference ... most probably from high volumes of tiny flakes of rust/iron (a VERY common dirt occurence)..... which then, you must back out of the JE mode ))).

9) It is your choice for 'tone options'.

I have YET to be able to handle a nail infested site with the detector in monotone.... and a Disc setting of '0'. This means that you hear absolutely everything.

It is not so much that a DE would over-engineer a detector to be audibly unintelligible; it's more a 'sensitivity function' of a gold prospecting capable unit..... coupled with a extremely fast microprocessor/clockspeed and very tight electromagnetic footprint eminating from the coil. Little flecks of iron will cause this particular detector set (F-75 & T-2) to sound electromagnetically unstable. On a recent hunt, I (as usual) was overdriving the F-75...and, in one area, it became electrically unstable (((so I thought))). Coil in the air.... and unit was stable. Coil on the ground and not moving.... and unit was mostly stable. Sweeping coil.... and EMI interference ensued. Hmmmmm....... let's dig some of these so-called "chatters". Resultant: About every 2" or 3"..... I was finding #2 lead shot from a shotgun.... at a depth of approx 1.5". I quit recovering them once I had about a dozen in my hand. The small spot of land that I recovered/removed these small BB's.... suddenly had no 'electrical chatter' in this one localized location of coil-sweep. Exterior of this sans spot,,,,, the electrical chatter resumed. I knew I was 'overdriving' the F-75.... and decided to drop the Sens to a setting of '70'..... and the ‘perceived’ electrical chatter (the BB-shot).... as coil was being swept.... suddenly vanished. I had desensitized the detector enough to no longer detect these small targets,,,, and the unit became stable again. Masking was still taking place though. It hurts me to drop Sens to lower levels; however, I could ascertain a more stable/intelligible unit and could then somewhat "hunt". (Targets beneath these BB's are going to be partially or completely "masked").

Another known engineering fact is that a single freq unit has the ability to handle Fe better than multi-freq units. Both types of units are still blinded (masked & silent masked) by iron,,,,, but the single freq units can ID iron with better accuracy, less falsing.... and a hair-splitting Disc setting is more ascertainable with a single freq unit.

Something worth mentioning; in reference to the CZ (and nearly all other units). When the coil is passed over a target (or multi-target co-locate scenario), the reporting circuitry will remain silent. When peak signal strength is ascertained, the detector reporting circuitry will STILL remain silent. When the electronics see the received signal strength 'start' to decay (decrease), then ....and only then, will the detector take a "best-guess" and report a target & ID. Keep in mind..... if multiple targets are under the coil at the same time, these types of detectors will wait until the largest COMPOSITE signal strength (only one) is achieved. And now...... the different animals; the T-2 & F-75. Their electronics and audio will 'fire' on ANY target,,,,, and take multiple "snap-shots" and report each one. Hence; the F-75 & T-2 will audibly sound very 'noisy'. Said differently: Let's say the dirt is Sans.... except for one single coin target at several inches deep. At a normal sweep-rate,,,,, the F-75 & T-2 will 'fire' many many many times (dictated by micro-processor clock speed) on the coin..... and report each 'firing' individually...... BUT; what do your human ears hear/register? It just simply sounds like one continuous "beep" to you. It's not! Now..... pass your coil over many extremely close (and very small) co-located targets with 75/2 and see if your brain can process at the same speed of the 75/2. You will also notice the VDI jumping radically. Do you think the VDI is incorrect!!!??? These steroiditic detectors (unfortunately) are mentally fatiguing......... not because of the detector,,,,, but due to our ears clock-speed. The CZ's are a MUCH smoother, MUCH better sounding unit..... and SO much easier to detect/hunt with. BUT, they can be quite blind (easily masked) and can close doors....... where the 75's/2's can re-open hunted-out sites with tremendous success…. especially with a slower coil sweep-speed in hi trash areas. ----Food for thought.

Happy Intelligent Hunting!

Thomas J. Dankowski

hi tom!
once again you have reminded one and all of the potential of this outrageously good metal detector design!..very inspiring!..tom!..thanks for sharing!

(h.h!)
j.t.

Tom, I have a great idea if you ever come to MN next spring/summer.

My back yard is not too large, but I had some really nice "relic finds" dating from late 19th century to the 1930's (only a few coins were found, mostly 1930's, 40's and 50's wheaties...and only a few).

Some friends and myself have tried quite a few detectors...ranging from mid/hi range whites, garretts, fishers, minelabs and tesoro's...

Nobody has ever found a dang thing but nails after I personally pulled out the several relics and coins...

My friend with his M.L.2 said it best..."Just too many dang nails. it's a shame"...because my house was built in the 20's, but my land had a home in it's place in the 1880's...hence, some of the older square nails (nails from many different era's).

Anyways, if you ever do come this way, I would love for you to utilize the laws of your compilation #1...bring the camera-men too.

The offer is always open.

You could not even "set up" a scenario like my back yard even if you tried...brown dirt w/ a share of red from old rusty iron nails...there for many years.

As far as recent trash goes...not to bad, there would be no bottle caps nor pull tabs, and only a few pieces of foil maybe...it's all nails and treasure.

This offer is for real...nothing much more then an invite, me and Lane (my wife) have an extra room (several) if you don't mind the dogs.

Oh, and we may be sodding or cementing/decking back yard in 2010 (last of several projects)...so dig away.

HH

-Mike



Edited 4 time(s). Last edit at 11/11/2008 05:32AM by PanMan.

Ok I dragged my feet long enough. I better post this before I forget. I did a lot of cutting and pasting from this site and others to come up with this. I have been using it as my personal reference.
Wingnut...

Fisher F75 Info & Tips
======================
This is a compilation of information I created from forum postings. Many of these are from Tom Dankowski.

Regarding bottle caps
---------------------
Sometimes dropping manual GB by quite a few points can give a substantial change.

in 2F or monotone, I can "usually " hear a distinct difference in crown caps and coins

Decompose/Oxidation characteristics do differ......... as do the TYPES and BRANDS of steel bottle caps. Ground dirt mineralization matrix can alter ID also. USUALLY... the "Conf" bar-graph scale on the F-75 will be low.... whilst sweeping over steel bottlecaps. Strong signal.... low 'Conf' is somewhat indicative of Fe bottlecaps. ....-----Just keep in mind... that a coin next to a nail will give the SAME resultant.

If you want to positively identify those pesky bottlecaps with the stock coil, try this.............
Sweep the coil across the suspected, cap signal , working forward until the signal is at the rear of the coil (the side of the coil that is closest to you) and then drag the coil back towards you and over the target, the full length of the coil. The resulting signal, if it is a bottlecap, will be a long, growl or grunt signal. If it is a coin or another good target, it will sound off with a short, positive signal.
Try it, it will work every time.
HH, bottlebum

__________________
BEFORE YOU DIG, Drop ground balance about 30 - 40 points (manually perform this).......... and see if these bottle caps (now) will start to ID better.......... or..........at least... go to a inconsistent ID on the F-75. Do NOT go to the 'BC' mode..... as you will lose too much depth capabilities........... unless everything is verified quite shallow (usually...this is hardly the case).

Regarding noisy backgounds
--------------------------
PROBLEM - changed the process to (j.e),and things went on full chatter!..backed gain down and it didn't help,so got out of j.e,and went back to (d.e)..for some reason i could NOT get the detecor to quiet down in de process either!
SOLUTION - Set Sens to around '40'..... then turn the detector off. Wait a minute...... then turn the detector on again..... THEN SLOWLY bring the Sens up. Yes .... the 'JE' mode will do exactly what you experienced.... in most places.



Overdriving
-----------
When absolute maximum overdriven performance is desired..... Sens MUST be on '99'. This is the FIRST step. Shut down your intents if you cannot ascertain stability with Sens on '99'.

NEXT....... IF no EMI is encountered with '99' Sens........ THEN you may start to bring Disc down. Start with Disc '6'. Try it with monotone or multitone; your choice. You'll start unmasking more targets in monotone with a Disc setting of '6'.... ASSUMING YOUR INTENT is to recover EVERYTHING that is non-ferrous.

IF the detector is still EMI stable.... see what happens to EMI stability.... by lowering Disc to BELOW '5'. '5' is not the magic number.... but '4' is!! Going to a Disc setting of '4' is where sensitivity receives yet another boost. And USUALLY............... when you are at a Disc of '4' ... and ESPECIALLY lower... is where multitone option is virtually required.

I have YET to be able to handle a nail infested site with the detector in monotone.... and a Disc setting of '0'. This means that you hear absolutely everything.



Hunting in a high iron area
---------------------------

Say; you have a silver dime and a nail 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'. 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. (((You will most probably recover the target))).

2. Say the F-75 is in 2-tone (or 3, 3H, 4, 4H tone options etc.....). Now......... the F-75 will respond with a 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.
I have explained this many times.... in many posts below; Sooooooooooo ,,, if my explanation is not clear enough here.... I may have done a better job in posts below.


NOW.......... that being said. (((( If you are in a nail infested area, and you do not audibly fatigue easily = = = )))) IF, IF, IF, you can handle a lot of noise.... and the detector can handle (not EMI plagued) a Disc setting of '0' and a Sens setting of '99'....then hunt in 2, 3, 4 tones (your choice),,, hunting for the "deepies". YES.....the detector will mask some targets in this audio selection config (ie 2, 3, 4 tones are selected) because any (heavily masked) target that VDI ID's as a '15' or below will present a 'iron' audio response (as so stated in example above),,,,, BUT, BUT, BUT the trade-off is; the F-75 will go deeper just by virtue of the Disc setting being '4' or below (especially '0').

Soooooooo, I am saying (by this set-up config) = MORE MASKING, BUT GREATER DEPTH. Hmmmmmmmm... trade-off. Which one does better? Disc '6' & monotone???? or Disc '0' and multi-tone???? The answer is: They BOTH do!!!!!!!!!
I am saying; HUNT the area in Disc '6' & monotone...... and do all the 'unmasking' that you can. THEN hunt in Disc '0' and a tone-option of your choice.... going for all the deepies.
NO...... you can not have both at the same time.... (((unless you're really good!!!))).

* 99% of EMI enters thru the coil. ((( Control box is not shielded....but is usually not the 'cause' ))) Dave J. & John G. are well-aware of the EMI issues, and understand the magnitude, the level of difficulties to mitigate this inherent single freq .... high powered unit's issue. And in the F-75's design..... there is minimum component-to-component 'cross-talk'.

* You have NO idea how difficult it is to design a 'functioning' detector. There are THOUSANDS of issues to deal with.... most interact/play AGAINST each other. There are MANY things we do not think of..... MANY things we are COMPLETELY unaware of.... that are 'exposed' in the design phase; MANY things rear it's ugly head! How do you know what you are missing...... if you don't know it even exists!!! Why would a rusty nail ID as a '4' at just a few inches..... yet.... STILL ID as a '4' at MUCH GREATER depths!!! And how DO you reduce internal component cross-talk!!! Which specific components are 'show-stoppers'!!! And just exactly what SPECIFIC.... and how MUCH shield paint must be applied to the coil !!! What are the thermal characteristiscs of each electronic component.... and how solid/stable/repeatable/reliable is each component as they change throughout operating temp changes!!! What material should be used for the face-plate film so as to mitigate UV breakdown!!! Pistol-grip foam density..... coil wire gauge so as to provide proper impedence; yet NOT change impedence AND NOT BREAK whilst donning/doffing coil thousands of times. THE LIST IS MILES LONG!
It's not easy guys..... it's not easy! The CZ took over 4 years in design... and Dave Johnson was NOT ready for release/product roll-out.... but was hand-cuffed by corporate deadlines & finances.

Beginner settings
-----------------
I like to see a beginner start off on the right foot. He/She will miss 'some' targets with moderate settings at first; HOWEVER, he/she is LESS likely to 'ditch' the hobby... if whilst cutting maiden voyage teeth..... the settings are NOT on steroids. Sooooooooooo........

Initiation settings:

Sens. = 70
Disc. = 06
Mode = PF
Tones = 4

As skill/learning curve is ready for the next journey..... then... the first thing increased would be Sens.

If you are encountering EMI..... drop Sens to say; '40'.... and raise Disc to '15'. "Cutting your teeth" with EMI is challenging!
PF or DE......... but never JE for the beginner.

Test Gardens
------------
Can you tell me what your mix of water and salt?
I used 3 gallons of water... mixed with two Morton's salt cartons..... which equates to 26 Ounces x 2 = 52 Ounces total salt.

Coil choices
------------

The 11" DD coil will give slightly better ID on deeper targets vs. the 10" F-70 coil. The 10" elliptical concentric coil is not quite as deep .... but will ID steel bottlecaps better...... for those that have areas they wish to hunt,,, that are loaded with steel bottlecaps. Target separation will always be better with the elliptical DD style coil. Pinpointing with the concentric coil is 'smoother'; pinpointing with the elliptical DD coil is 'sharper'.


F75 Specs
---------
Operating Frequency is13Khz
Weight 3.5 lbs with batteries in it
Battery life typically 40 hours with good Alkaline

Teknetics T2
------------
The T-2 is the predecessor to the F-75. The T-2 was released over a year before the F-75's debut. They are nearly identical detectors..... except that the F-75 has a few more tools/featureset..... and is a bit deeper.


Cz 3D vs F 75
-----------------
You MUST invoke "4H" mode on F-75 so as to compare apples-to-apples. By no accident, the "old coins" program in the F-75 (& T-2) are nearly hair-splitting identical to the 3D. Remember to recover the 3rd highest tone w/F-75 & T-2. . . With that being said, the CZ-3D "coins" high-tone (although nearly identical to 4-tone F-75/T-2) will "jump" out at you moderately better.... and be more of a 'smooth' audio response vs. the F-75 & T-2. Easier/good for the beginner, novice & amateur hunter. The 75/2 is a more ragged "real-time" ..... faster then the human brain "snap-shot" processing of target....and converted into a twitchy, high-powered punchy audio...... ready to hair-split, reset "snap-shot" the next target in an instant. Real-time/real-world audio. Best for amateur and professional. It is usually quite an eye-opener for many folks to learn just how much trash & targets are in the ground in the bulk of the areas that we hunt....and,,,,, for the first time..... the F-75 brings this to light. Yes, you can run the F-75 & T-2 at lower Sens settings and enjoy coin hunts with a bit more of a 'smooth' response.... and at a lower mental fatigue rate. (I prefer steroid settings). In most cases, the F-75 & CZ-3D have nearly identical overall depths on coins... and in a wide variety of dirt mineralization applications. The more trashy the location,,,, the greater the "effective depth" capabilities of F-75 over concentric co-planar units. Once again, it's an eye-opener. In low trash/no trash environments, the CZ-3D w/optional 10.5" coil is untouchable for overall deep-seeking depth abilities. In VERY severe dirt conditions.... the slow-response Explorer leads the pack.

Best headphones
-----------------------
My primary headphones are KOSS QZ-99 Noise Reduction phones. Heavy, bulky and hot.... but the outside world nearly goes away,,,,, allowing greater focus on detector audio. Wind noise is no problem. Great for the beach.


DFX vs. 3D
--------------
DFX lacks approx 1.5" depth on coin-sized targets (on average w/avg soil conditions).
DFX has larger stock coil.
DFX has wide nickel window..... consequently finds too many newer flip-tabs (square-tabs) that read 'nickel'.
DFX very stable unit.
DFX has quite a few pages of menu's for set-up. (Not K.I.S.S.).
DFX slightly better balanced.
DFX reads older Indian Head Cents 1860's, 70's & 80's... many silver Half-Dimes, tilted and/or slightly masked coins as "tab/trash".

F-75 Disc '6' & mandatory 'monotone' justification
-------------------------------------------------------------------
F-75 Disc '6' & mandatory 'monotone' justification: Many have asked "WHY?".

-------- 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......AND....... consequently,,,, 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.... and 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 Disc, ....even though it's set on '6'...... will instantly become a Disc setting of '15'. The Fault; Half human and Half detector. What does this mean? = Any target that is between a Disc level of "6 thru 15" will now audibly report as a "Low Tone" (iron tone). BIG PROBLEM for a multiplicity of reasonings. And any target that is ABOVE a "15"... MIGHT read a higher tone,,,, (tone freq depending on what tone option is invoked). -------Most folks do not dig iron. And most folks will miss masked non-ferrous targets when 'monotone' is NOT selected. Said differently via utilization of a "extremely common occurrence" example;

----- Recently, I recovered a badly masked Barber dime. When I detected this severely handicapped dime, the F-75 was in 'monotone', Disc '6', 'PF' and Sens on '99'. In monotone, the dime AUDIBLY sounded good. (( I was going to dig this target )). The VDI was terrible - would/could NOT lock on to anything close to resembling a highly conductive piece of silver. I then invoked 2-tone..... leaving ALL other settings alone. Now.... the dime was constantly audibly reporting as low-tone/iron-tone.....even as I rotated my body around target. The VDI was jumping all over the board. I made the decision to NOT recover the target..... and walked away. Several hours later, I decided to go back and recover this target (and MANY other similar responding targets)..... with F-75 back in 'monotone'. Results = One 2" nail, two 1/2" nails..... and one 1893 'O' Barber dime. Yep; MOSTLY iron. The 2-tone mode did not lie. Justification = The composite of the 4 targets (3 nails & one dime) were higher in conductivity than any one of the nails individually...... but TOTAL conductive composite was HIGHER than any nail (or combination of nails) would have cumulatively registered. Because I (and the detector) knew that the detected target (suspected co-locate/composite of multiple targets under coil) was higher than the conductivity of most nails... yet STILL ID'd in the 'Fe/iron' range...... this target was needing recovery. Good thing! Selecting any other tone options..... and the detector would audibly report the composite as "low-tone/iron-tone". Yes, the F-75 will still unmask more non-ferrous targets than other detectors..... even if 2-tone or multiple tones are selected; however, an even greater level of unmasking performance can be ascertained when unit is placed in 'monotone'. ((( The T-2 with a Disc setting of '21' is the exact same thing as all of the info above ))).

This is Approx 10% of F-75's capabilities.


F75 details
--------------
The Time Domain/Recovery Clock-Speed/Clock-Freq of the microprocessor on the T-2 & F-75 are identical. ... And I have found myself locked into the 'PF' mode on the F-75 for inland hunting (especially Fe infested dirt). A entirely different set (SET 2) of operating parameters are required with F-75 in 'JE' mode. Different Disc & Sens settings in particular. SET 1 = 'bc', 'de', 'pf' operate fairly similar..... with sub-set 'bc' mode presenting the greatest difference out of the three,, within SET 1. I'll nearly never use 'bc' mode..... as it induces too much masking back into the equation; hence, defeating the F-75's #1 highlight.

If you need to perform maximum unmasking abilities..... monotone is a requirement.


Phantom coins
-------------------
Problem: I had 4 good repeatable high tones reading in high 80's that read from 8 to 12 inches deep. When started digging and got to about 6 inches deep stopped and ran coil over hole again and no signal.

Solution: Dig a small hole on the surface.... and a WIDE/DEEP hole underneath/underground.... and you will probably find that the coin kept falling deeper into the hole.... and ON EDGE!
If this fails..... Drop Disc to '0' and remove the mask that is in the excavated pile of dirt. It MOST PROBABLY will be a heavily oxidized/rusted bottle cap.
If this fails..... look for the blood spot (iron oxide) red/brownish discoloration in the soil ..... for the disintegrated Fe object. If found... keep in mind.... this may SILENT MASK your intended target. Spread the dirt and check again.

GB the F5
-------------
Just thumb the disc button down to the AM mode. (Autotune). Press and HOLD the phase lock button down. Pump the coil. .... (from between and inch to about 6 inches off the ground).....and when the GB and phase numbers match (usually after only two or three pumps)....release the button while STILL pumping. Thumb it back in Disc mode...........and your in buisness. You can do this with ONE thumb, right or left handed. (I'm a leftie, but can do it easily with either hand.....) Takes about 10 seconds to do.

Gold on the F75
---------------------
Q: I know gold id's in the 8-45 range using the f-75, but is there any way other than digging every signal to distinguish it from foil?
A1: The only chance is when it's a gold ring, this should give a fuller(rounder) sound. And at times a medallion depending on shape & size will sound fuller. But chains, earrings, broken rings, broaches etc can sound pretty ratty like foil. Kind of goes with the territory, harder work yields the better finds.
A2: When I get tired of digging foil signals I do start becoming more selective, instead of giving up completely. I look for signals that do not vary in ID#s no matter which way I sweep the coil over it. I ALSO listen for a double blip. Back when I only did the beaches, most foil signals that gave off the double blip as the coil went over it was a ring or a washer or something with a hole in it like a pull tab ring.



Edited 1 time(s). Last edit at 11/24/2008 04:27PM by Wingnut.

Hi Tom,
It's almost impossible to add anything additional to your post information wise that may benefit someone because you covered so much very well.

I can only add this, even with the DD coils you need to overlap, overlap and overlap some more in high iron infested areas. Just as with concentrics these new DD coils most definitely have a small sweet spot at depth for hitting co-located ferrous/non-ferrous targets. Getting consistent repeatable hits audibly and visually requires careful attention when resweeping due to this fact. Regarding older nickels in iron (at least in MY ground) I have yet to see a TID machine T2 included, that will come close to giving any kind of consistent reading on the tougher nickel hits. The TID will bounce from high foil to high tab and thats about as good as it gets. Of course once knowing that, at older sites that is all the target ID info one needs to pick them out! Use single tone audio and beep-dig.

Tom

Thanks for the offer Mike. Would love to travel the country.... but I'm still in my 'working' years. Would love to detect for a profession.

Wingnut = Good compilation. As time permits...... I'll try to perform more compilations. Sometimes it's MUCH better when (through the eyes of someone else) compiles this info into a 'usable' source..... as my priorities/interests may differ. .... Thanks.

Thanks Tom. Yes, nickels are one of the most difficult coins to properly ID to begin with..... then add depth, minerals, masking etc..... and the problem compounds. This is one of the reasons as to why it is a good idea to dig the mid-tones that are at the same depth/strata that the wheaties & silver are being recovered.

Tom

in an older park fully expecting to retrieve a Buffalo nickel. What I got instead was an IH penny that "should have" given the tab/zinc bounce. Of all the odd TID recoveries I found with that old CZ5 that one stands out the most in my mind. Kind of like your Barber dime experience which I'm sure you will alsso never foerget.

Tom

Lots of research you have looked up...good job!

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!

Hi Tom,
Great post and most informative! I was wondering if these settings would also apply to the F-70 with the exception of the PF and JE modes. I also would like to know what your threshold was set at and how this affects the performance of the machine. To give a little insight I was a Conistrike user for the last 6 years and the threshold seemed to have much more influence on the depth of that machine than did the sensitivity, at least that was my experience.

HH,
Bill

I to would like you opinion on that Tom. A true threshold type sensitivity adjustment from what I understand should not lose a mid depth target that gives a decent response even when turned to minimum... as with the 1270, X5 and T2. The Coinstrike was one of the first detectors to seperate the sensitivity and threshold functions but, what we don't know is what Dimitars thoughts were on how it should be implemented. It seemend to me that at lower sensitivity levels the threshold "curve" changed so that depth was fairly well maintained. But I could be waaay out in left field on that!

If only somehow Dave could come up with a way to use 2 tones but retain the iron see-thru you get using low disc and PF 1 tone. Maybe the tone break shojuld follow the disc setting?

Tom Z



Edited 2 time(s). Last edit at 11/12/2008 11:43PM by Jackpine.

Bill & Tom,

Yes, all of the above applies to the F-70 also. Keep in mind..... the F-70 (overall) has nearly identical performance to the F-75... but MUST have the same coil as the F-75 (yes, can be interchanged). With the 9.75" elliptical coil on the F-70.... on average,,,, there is approx a 1.5" loss in depth capabilities on coin-sized targets. This can be circumvented by installing the elliptical DD 7 x 11 (F-75) coil on to the F-70. As far as F-70 threshold..... I have noticed minimal/negligible variation differential with performance operating characteristics...... having changed entire spectrum availability on the F-70..... with Florida dirt conditions. On the F-5, slight changes in threshold... presents dramatic performance changes. On the Coin $trike..... the Threshold function is akin to the F-5.... dramatic. There was to be (some form) of linearity with Thresh adjustments.....but varying dirt (and other variables) will alter this to some extent. Yes, I fully agree that a mid-depth coin-sized target should NEVER disappear..... no matter what Thresh value is dialed-in. The C$'s intended target was to tackle black magnetic dirt. It performed such..... (almost) regardless of coil-sweep speed,,,,,, and would trump a multifreq CZ. Dimitar performed such matters with the utilization of a single freq 7.1Khz platform. Commendable..... all things considered (details refrained). He was hired by FRL.... given a clean slate..... and deliberately NOT given ANY blueprints to currently-in-production designs...... so as to circumvent "preprogramming" of already-existing mindset. Considering the utilization of electromagnetics in electromagnetic dirt (yep, self-defeating)... he accomplished a mission of partial paradox.

Tone break following/tracking Disc setting is nothing new.... but can be a tremendous aid. I believe the Cobra II (and others) employed such function.

It is only now....... with the utilization of F-75/T-2....... are we BEGINNING to learn how critical (and how crippling) iron masking truly is. @#$%&'s box has been opened....... no one wanted to face (tackle) the music..... ((( many never even knew it even existed; hence, could not combat a 'unknown' problem ))) and MOST designers choose to NEVER open this box. Bruce Candy has performed masterfully with this problem..... but in a tangential expenditure by virtue of HIS type of (magnetic/iron) dirt.... with the inception of FBS incorporated into the Explorer. It's just that..... even with the recently released Explorer E-Track...... the unit will "null" TOO TOO much in nail-laiden soils. This portion.... I simply can not accept. . . . YET.... I highly praise the Explorer's 'bad dirt' handling capabilities.... (a product of Australia dirt). IN THE MEANTIME..... Dave & John made the maiden 1st tackle. Single freq (which handles iron better), correct selection of freq, extremely tight EM footprint elliptical DD coil, large-scale iron Disc adjust, extremely rapid processing clock-speed microprocessor (matching....or exceeding/beyond human brain processing speed,,,,...... sometimes frustrating the fallible 'human' element)..... and a host of other attributes. It certainly has revolutionized the way we think/hunt...... and "opens the mind" to future exploration & possibilities. How do you commend?

Tom

for the info on the F70 and C$. Thinking back to when I had the MXT I believe the Relic mode had the tone break follow the disc setting. Never used it much as I preferred the C/J mode for its iron range adjustment just below 2 on the dial. Very informative audio on low conductors when set in that range.

Yup the C$ will trump the CZ in several situations. Shallow fresh water wading over exposed glacial gravels was one area it outperformed the CZ.


Tom Z

Great info Tom I am going to try this at the old camp from the 1800 on turkey we hit it hard with the F75 and the second time targets were hard to find. But I pulled out six half dimes from 1834-1838.

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!

Yes, on the White's MXT.... the pinnacle iron Disc setting was between 1.8 to 1.9 (almost exactly 1.9).........and this was on 4 different MXT's. Stunning/impressive tight tolerances from detector-to-detector. Exceptionally impressive.... considering analog 'dials'.
MXT is VERY quiet in the iron. Commendable. Yet, , , problem is......... it's TOO quiet; .... ie 'masking'.

Tom do the settings you wrote about work for the small coil? I also found that I could not use mono tone with a disc of 6 my machine went crazy and as good as I am I had to go for the multy tone and disc at 0-4. I have used the mono tone and 6 disc on areas that are not so filled with trash and love it when I can use it that way. I still dig a lot of bad targets but the high to mid tones gives me a heads up!

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!



Edited 1 time(s). Last edit at 11/18/2008 02:37AM by Lawrenzo.

Yes, the tone options function in exact same fashion on F-70/F-75 with the smaller coils.

GREAT information Tom! Outstanding compilation of F75 knowledge... Thanks!

Time permitting...... and I'll try to post another one.

Thanks for compiling this information Tom. Your research efforts make for very instructive reading, and valuable practical field applications. While I have not posted recently (warm weather travelling), I am present whenever possible, always reading and learning.

I've enjoyed using the F-75 for quite some time now, including an extensive prospecting trip to silver mining country. The 75 performed superbly, stability (EMI) never an issue at all...despite being in close proximity to the big transmission towers, urban areas at times... and other detectors at very close range (did observe an MXT became erratic when within seven or eight feet of the 75).

It handled reasonably high ground phase mineralization (GB=85ish) easily while running at max sens in JE mode with iron disc usually set to 12 (or PF mode with disc set to 6). Normally I did not run the sens at max due to extreme sensitivity to very tiny distracting non-ferrous targets of no interest to me, but the point is...I could have, and frequently did when the ground conditions seemed appropriate. I have also found the 75 to be very responsive to lower conductives (nickel range....which applies to most silver ores) at excellent depth...a real plus. Sufficient to say I would not be without this unit, ever.

Regarding the MXT. A fellow detectorist asked about the 75's autotune speed as compared to the MXT's max hyperSAT setting. I was unable to answer that question. Would you kindly comment on how these two units compare in that regard? Thanks....

Jim.

Hi Jim,

Welcome back. I can only surmise the F-75's processor speed is faster vs. the MXT's Sat speed. That's one area about the MXT I have not researched.....as of yet. (( I have a small pile of CZ-3D's on the bench requiring Calib for several folks )). Yes, the T-2/F-75 operating freq is much more resonant with lower conductors such as foil (and nickel) range. While this may not be good for coin hunters; it sure performs for the relic hunters. This is not to imply the F-75/T-2 are handicapped with coins; in fact, it is other attributes of design that makes up for it's lack of resonance towards coins. Extremely narrow EM footprint, Fe handling capabilities, unsurpassed microprocessor speed, mineralization handling abilities due to 13Khz.........,,,,,,,,, just to name a few.

Sounds like the dirt you are running in..... w/GB = 85ish,,,, is fairly hot.

Tom

Thanks Tom, it's good to be back here again. The opportunity to finally put the F-75 through it's paces in a prospecting environment, and conduct a few simple tests while on site was instructive. My 75 (christened "Black Bart") located (with some guidance) many beautiful silver specimens and nuggets, large and small.....exceeding even my high expectations, while putting any EMI fears to rest permanently.

"Sounds like the dirt you are running in..... w/GB = 85ish,,,, is fairly hot."

Yep, but the 75 ran smoothly at all times. On site, my first test was to check a pure nickel content Canadian nickel at about 10 inches depth to see what might be expected in those ground conditions. The unit easily gave a loud, two-way repeatable, solid signal (max sens, any disc mode in zero disc, or in JE mode with disc set anywhere up to "12" for a crisp signal)...even raising the coil a few inches above ground before the signal abruptly failed. The all metal motion mode also signaled well on this target; we've discussed the all metal motion mode depth capability trumping disc modes in the past (which I don't doubt at all), yet I must say that the disc modes (used in the settings described) provided a crisper signal... JE mode was more impressive since small iron disc settings did not detract from the signal strength/depth capability.

My MXT (with the 10" DD coil) would not signal on the 10" nickel, although it would respond with a softer, repeatabe two-way signal on the same nickel freshly buried at about 8 inches depth. An excellent result, but not in the same ballpark as the F-75. I should further add that in undisturbed ground, 100 year old mine tailings for example, I checked innumerable signals with iron discrimination in place with both the PF, and JE modes. I did not discern any difference in depth capability, which was a satisfying result compared to the freshly buried coin garden at home. A real confidence builder, I elected to use the PF mode over the JE mode in areas where tiny non-ferrous junk became distracting...without fear of losing depth performance.

It's interesting to observe that in remote areas... removed from many of the usual urban EMI sources...but still subject to the large transmission towers within as little as a few hundred yards at times, the 75 was dead quiet at all times with max sens in any disc mode while holding the 11" coil in the air; not an unstable peep, and what a pleasure to use on the ground with small iron discrimination. By comparison, there were "hearable" but not in any way distracting "sound nuances" in the all metal mode with max sens while holding the coil in the air. On the ground was a different matter, as the unit would signal on many tiny targets, both ferrous and non-ferrous, including countless conductive bits of a common iron sulphide ore, namely... pyrrhotite.

By contrast, while I also was favourably impressed with my MXT, under the same remote conditions.... while holding the coil at waist level in the air... the MXT was quite "chattery" at higher gain levels. These observations lead me to believe that most instability users experience with the F-75 in urban areas, particularly in the disc modes, is a direct result of EMI only...and not "circuit noise".

I wish the F-75 speaker volume could be increased beyond it's current max setting; out in the wilds I prefer not to use headphones (bear country), and I observed that natures innumerable little sounds (ie. wind in the trees) made it just a bit difficult to hear smaller signals clearly. In contrast, the MXT has ample volume and then some.

Jim.



Edited 1 time(s). Last edit at 11/26/2008 03:16AM by HumblePie.

Tom, Thanks for the recap..and futhur evluation and settings of the F75..I got my F75 back form fisher for the upgrade and silent coil issues.the DD coil was Bad...
Its time to get serious about some great relic sight I have lined upI will use your setings as theres Gobs of Square Nails and several Barbers have Been found at the site in the Past..

Jim Its great to have you Back I;m glad to hear you liked the F75 Performance on your silver ore hunting.You have any pic of your findings..I hope to be around more oftenthings have gotten outa hand busy over the last several months.james

James, the F-75 performed just fine prospecting. As noted above...absolutely no instability at any time...even in close proximity to those huge transmission towers. Dead quiet.

By the time the wife arrived some three weeks later, I let her use the 75 in PF mode with full iron disc, sens started off at 60....a modest set-up for a novice searching a trashy area. She's never been much interested in metal detecting, but still made several good finds. Her interest level significantly increased by making those recoveries, and I am certain she quite enjoyed using this unit with it's simplicity and light weight.

I could not fail to notice how quickly she caught on to the unit's nuances with a minimum of help. The most common comment she'd make was wrt larger iron pieces; she'd dig it, then indicate she wanted to be certain of the target ID, but...the unit usually did provide a tip-off if she'd paid strict attention. Another frequent remark was that (because good targets are hard to find) she'd try to "work a sort of OK signal into a good signal", but no dice...the unit would have none of it. She'd dig anyway, and sure enough...larger iron.

I don't know how to post a photo here James, and am not sure it's a good idea anyway...Jim.

Jim,

Your type of hunting in concert with your perspective is always fascinating. You are the only one (that I'm aware of) to use the F-75 in the capacity of nugget prospecting. I know the bulk of the crowd uses it in a more general fashion..... relics, coins, jewelry etc. ,,,,, yet, I'm certain the unit has merit in your capacity.

As far as the level of stability (zero EMI) you are encountering .... is a good thing.... and a resultant of your environment. I have brought the F-75 (and previously the T-2) into a Tempest booth... to verify EMI is prominantly (nearly exclusively) a product of external induced noise. Yes, JE mode, Disc '0', Sens '99' etc...... Tempest booth results; extreme stability except for a one-time failure. I had F-75 deliberately placed in a air-conditioned room that was at 62 Deg..... whereas the Tempest booth was at 78 Deg. This temp delta induced Ckt board condensate/moisture.... causing component-to-component cross-talk. This test was performed to validate a concern about removing unit out of a A/C auto.... then proceeding into hot Florida humid weather.... and, sure enough, EMI instability ensued.

Recently, I have had several areas where absolutely zero instability/EMI was encountered ((( not the norm ))). This was with Disc @ '0' and Sens '99'...... and PF or DE mode. Shaking the unit induced nothing..... nor did holding the coil perpendicular to Gnd. ---- If Sens adjustments are somewhat linear, I surmise a Sens setting of approx '139' could be utilized .. before instability would encur. If only to have this ability. Or.... if only to have a 7" x 11" elliptical non-DD coil so as to ascertain the depths required for older era/generation targets under many common conditions around the globe. Invoking some form of a special mode to acquire this level of performance may be required so as to prevent beginners from getting themselves into 'such a common beginners mistake' trouble.

Tom

Jim its great your wife liked using the F75...Sounds like your adventures are a chance and a life time for most..Glad you had a good time..Cant wait to here more..I have some gold nugget hunting comming up in the future and cant wait to get results...james

There's so much I can't process it all. Thanks Tom

Understand. May require a re-read a couple of times.

..................and bringing this one to the front of the forum.



Edited 1 time(s). Last edit at 02/21/2012 12:34PM by NASA-Tom.

Bump..... with intent.