F70 vs F75 Iron Handling ?

Tom I read your article in the most recent Fisher World Treasure Newsletter on "F-75 Peak Performance."

I was trying to equate the information to the F70. I've always (and perhaps incorrectly so) thought of the F70 as a F75 with less options, and for the most part assumed that coil for coil (say 11" DD for instance) both machines to be fairly equal in performance (depth , separation, and unmasking ability in trash and iron).

You reported that on the F75 when the disc is set to 6, and you invoke a tone option other then monotone that the disc is, unknowingly to the user, changed to 15 (any idea why?). I do not believe this is the expected behavior on the F70, and the disc level remains at the setting the user programs regardless of tone options.

So with this behavior aside, would the benefit of running monotone on the F70 simply be less audio fatigue? It seems like an old way of looking at target recovery, as it's almost like hunting in all metal mode. You'd be glued to the screen trying to get a read on the TID# deciding to dig of not to dig, as the tone itself wouldn't provide a lot of information about the composition of the target (actually if it's grouping multiple targets into one tone, it almost would appear to mask targets).

I'm trying to get the most out of the F70, so any F70 specific feedback/tips/tricks on it's iron handling capabilities would be greatly appreciated.

TIA,
Brian



Edited 1 time(s). Last edit at 08/15/2009 12:26PM by Cal_cobra.

You know........... I need to clarify something. Something that I said that is misleading. With both the F70 & F75........ if you are in monotone with a Disc of '6'; anything that ID's below this '6' Disc setting ...will be silenced. Anything ABOVE a Disc of '6' will give you "A TONE". ONE TONE! A MONOTONE. And probably a fairly good length audio tone......prompting you to dig (((assuming you are relic hunting and trying to unmask non-ferrous targets in a iron infested site))).
If you find.....say... a target that ID's as a '13'..... and you are in monotone.........NO PROBLEM. You will hear a good audio-length target response. NOW..... if.... on this same (VDI of '13') target..... you decide to switch to ANY other tone option (other than monotone)...... this VDI of 13 target will now give you the low 'iron' tone ..... and you will most probably NOT be digging iron targets..... and this target(s) will be missed. What's happening is: When you invoke a tone option OTHER than monotone....... say 2 or 3 or 4 tones......ANY target that is a VDI of 6 thru 15 will NOW give you a iron (low) tone..... with a good audio length report. A target with VDI conductivity of '15' or below..... is NOW a low (iron) tone........ instead of a 'investigatable' good monotone..... when you invoke more tones above the monotone. Your Disc is still at '6'....... but instead of a good "dig me" monotone........ you will now hear the iron (low) tone on targets that are in the VDI (severe masking) range of 6 thru 13.
Assuming you select a Disc setting of '6'.....When any multitone option is selected...... targets that are in the VDI range of 0 thru 6 will be Disc'd out. Any target that ID's at 6 (actually 7) all the way up to 15..... will give you a iron (low) tone. A target of VDI conductivity of '16' or above will now give you a 'upper' tone..... depending upon which multitone option you select. Usually when relic hunting.... you do NOT want to miss targets that VDI in the range of 6 or 7... all the way thru 15................as....... especially in thick iron...... this is where a lot of masking; (subsequently unmasking) takes place.

Tom

Great info..Tom..I have experianced this is Old Home places..Takes a little getting use to..

Hi Tom,

Thanks for your reply. I figured the discrimination would work as expected (silencing targets lower than your disc setting), but wasn't sure about the less than 15 'disc to tone reprogramming' when using multitones. It's good to know the F70 is the same as the F75 in this regard, as I was under the impression that a multitone option didn't change anything behind the scenes on the F70 when using a disc setting lower than 15. I need to setup a test garden so I can have a controlled environment to try various settings and coils to see how the F70 can best unmask non-ferrous targets next to iron.

At an old California adobe site I hunted in AM mode and it worked great (very few targets). I got a lot of #12 TID's which I dug (there was some discussion on another board about deep targets on the fringe of detection getting their TID pulled down into the iron zone) and they were all old nails, although nothing was deeper then 6". Prior to hunting this site in AM mode, I was using the 3H tone option, disc @ 6, and recovering any signal above the iron range. At this site AM is the perfect option as the site has highly mineralized ground (next to a volcano) and in disc mode you get an abundance of ground noise, but it's smooth and quite with AM mode.

Thanks,
Brian

NASA-Tom Wrote:
-------------------------------------------------------
> You know........... I need to clarify something.
> Something that I said that is misleading. With
> both the F70 & F75........ if you are in monotone
> with a Disc of '6'; anything that ID's below this
> '6' Disc setting ...will be silenced. Anything
> ABOVE a Disc of '6' will give you "A TONE". ONE
> TONE! A MONOTONE. And probably a fairly good
> length audio tone......prompting you to dig
> (((assuming you are relic hunting and trying to
> unmask non-ferrous targets in a iron infested
> site))).
> If you find.....say... a target that ID's as a
> '13'..... and you are in monotone.........NO
> PROBLEM. You will hear a good audio-length target
> response. NOW..... if.... on this same (VDI of
> '13') target..... you decide to switch to ANY
> other tone option (other than monotone)...... this
> VDI of 13 target will now give you the low 'iron'
> tone ..... and you will most probably NOT be
> digging iron targets..... and this target(s) will
> be missed. What's happening is: When you invoke a
> tone option OTHER than monotone....... say 2 or 3
> or 4 tones......ANY target that is a VDI of 6 thru
> 15 will NOW give you a iron (low) tone..... with a
> good audio length report. A target with VDI
> conductivity of '15' or below..... is NOW a low
> (iron) tone........ instead of a 'investigatable'
> good monotone..... when you invoke more tones
> above the monotone. Your Disc is still at
> '6'....... but instead of a good "dig me"
> monotone........ you will now hear the iron (low)
> tone on targets that are in the VDI (severe
> masking) range of 6 thru 13.
> Assuming you select a Disc setting of '6'.....When
> any multitone option is selected...... targets
> that are in the VDI range of 0 thru 6 will be
> Disc'd out. Any target that ID's at 6 (actually 7)
> all the way up to 15..... will give you a iron
> (low) tone. A target of VDI conductivity of '16'
> or above will now give you a 'upper' tone.....
> depending upon which multitone option you select.
> Usually when relic hunting.... you do NOT want to
> miss targets that VDI in the range of 6 or 7...
> all the way thru 15................as.......
> especially in thick iron...... this is where a lot
> of masking; (subsequently unmasking) takes place.
>
> Tom


You know, I never really misinterpreted your earlier explantion but a different statement may help. The low tone in 2F/3/3H/4/4H only signals a target in the lower range of the active discrimination range. I've never tried DISC=65, but I suspect that the low tone would ID stuff from ID=66 to 70 for example, clearly not "iron". So you could hunt in DISC=6 @ 3/3H/4/4H knowing that the low tone is IDing stuff in the 7-15 range that could quite possilby be nickel, copper, silver or gold masked by iron. I like the 4H option since a high tone will usually ID a good target. But you can get lazy that way, never digging the low tones if you are in a hurry to hear the high pitched stuff.

If you are on a Disc setting of '65'.... you will NEVER hear a low tone.....,,,, no matter how many tones are selected. I could also extend this to saying..... if you have a Disc setting of '15'..... you will never hear a low tone.... no matter how many tones are selected.

I also NEED to say that Disc vs. Audio report vs. what actually shows on the VDI are ALL DIVORCED from each other. Yes, , , most of the time... they will 'closely' agree...... but when you get into thick iron..... a disparity/incongruent differential occurs. You may find that (in your specific location.... and specific decomposition status of YOUR specific nails/iron)..... the bulk....if not all..... will 'just barely' Disc out at a setting of '6'. BUT.... if you drop the Disc to '0'.... you will see many/most of these nails ID between 5....up to 12. YET...... a Disc setting of only '6' on your detector; and nearly ALL of the nails no longer present a audio response; HENCE, the divorced status of Disc setting vs. audio output vs. ID.

I really did not want to get into THIS MUCH technical data (yet) as folks may want a little more digestion-time...... of the above material.

Tom

Sounds like I need to do some more 'experimenting'!

Tom you should help design a new detector no one could figure this out less they were very smart. loved the hobby, and hunted for years. And working for NASA must help also.

I would think Fisher would be on the phone picking your brain and not waiting another five years or more to come out with a new platform. I still have not read a whole lot of info proving the V3 is all they said it would be. It is I am sure a great detector but for all the freq and graphs it seems to not do what I read it should do.

LowBoy

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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 this is a good discussion, some great info here and food for thought.

I knew the audio and TID were independent, but adding the disc behavior into the equation really emphasizes the importance of using the monotone setting for thick iron hunting, I'm looking forward to trying this out.

Between the F70, Edge and Omega, which do you think is the better machine for unmasking non-ferrous targets in thick iron?

Thanks, keep the info coming :-)

Brian

The F75 for sure and then the F70 as far as Tom's info he does live in an area where the ground is a lot different from Calif. So the F75/F70 may be a bit different in our area.

I tried the edge in the gold country the F70 a frined lent me his with the 11 DD the CZ 70 pro and F5 with the DD and then the F75.
I liked the F75 the best the info was more clear the VDI info was more to my liking the mono tone sounded better.

I like to use one detector as long as it can do all I need it to do. The F75 has never let me down except for EMI and the F5 is no better. If you put the 5"DD on the F75 it hunts better but is harder to hunt with in big areas.

The Cz3 was a great machine and I had very little prolbems but it is so slow that I had to sell it.

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!

Brian:

1. F70 w/11" DD.
2. Omega w/11" DD.
3. ID Edge (a distant 3rd place).

.....When you are in an area where most of the nails are ID'ing as...say: '12'.... place your Disc on '8' (then sweep)..... then '7'(then sweep again).... then '6' (then sweep again)..... and see where they are ACTUALLY Disc'd out. In most cases; it's nearly CERTAIN to NOT be where you would rationally expect.

LCPM:

Conceptually... yes, I have a few..... with one being 'out of this world'. Sometimes external-source pride places me to be in a position of 'forced silence'. Plus; I'm a bit over-protective for 'release'. Resultant; Human growth stunted.