My F75 must be slightly related to a church mouse

[Mike Hillis]

Yesterday morming when I was looking at my detectors to choose one for the morning, I decided to swing the F75 LTD and, just in case I couldn't use it I also grabbed the Land Ranger Pro (LRP).

At the time I had the 11"DD mounted on the F75 and I had the F75's 5x10 DD coil mounted on the LRP. The F75 coils on the 7.7/7.8 kHz units aren't fully compatible, they hit hard down to about 6-7 inches, then cut off. Its like detecting with a governer on the sensitivity. Works ok for me as thats all I need most of the time and it effectively deals with my EMI issues.

I headed to a middle school athletic field to do some ring hunting. Once there I removed the 5x10 DD from the LRP and put it on the F75. Turned it on and here comes the dreaded EMI. I checked my DST setting, it was 9.0. As a matter of habit, I start running througth the frequqncy shifts and low and behold it goes quiet at F1. Way cool!!!!! So DST 9.0, freq setting of F1 and I'm stable. How sweet! Set my disc and notches were I like them on the F75 for ring hunting, Disc at 23, notch out high zinc, DP tones. Sens was too high for my ground so I dropped it down into the 50's and what sweet time I had sweeping, listening for those richer lower tones. No gold this time out but it was sure fun using a stable F75.

In fact it was running so stable I had to try it out at one of my high EMI sites. So before I quit for the day I headed to a place where I test EMI responses and low and behold it was stable here too, even in FA Mode with 99 sensitivity! I have never before hunted in a stone code silent FA mode before. It was so quiet I thought my F75 was broken. But nope it was working totally stable. Then I thought ok, maybe there is some silent masking going on, but no, I pulled one of the nickels out of my pouch I had found at the first site, and verified that I wasn't experienceing any silent masking. It was just totally stable.

There is nothing like hunting with a totally stable F75. Nothing like it in the world.

HH
Mike

 

[Rob in (Ca)]

Thanks for sharing Mike, One thing I noticed with the F-75 is that average size Rings

(Like men's wedding Bands) come in at the (nickle zone) on all my other Pass detectors.

On The F-75 they all come in at The Foil zone ?. My Ring hits at 23,

Digging (All) of The foil zone is a Must!

 

[Jackpine Savage]

Mike

How does that setup work out in the tot lots swinging near metal poles?

Tom

 

[Mike Hillis]

Hi Tom,
The F75 and this coil work pretty good around the support poles. You can turn down the sensitivity to 0 on the F75 and still get acceptable depth with a mininum possible coil foot print. The only reason I didn't have this setup at the top of the list was due to my EMI issues. I still don't know if this is a fluke or not but I'm going to do more checking during my long holiday weekend.

I need to find the key so I make this experience the norm and not the exception.

HH
Mike

 

[Mike Hillis]

Hi Rob,
I'll have to check into that. The last gold ring I found with the new F75 was a women's 14 KT gold band and I don't remember the TID reading. I kept it and a very very thin 18K white gold ring for testing. I'll have to do some bench testing and get back with you. I think I'll ask my wife if she'll let me test our wedding rings too. I don't know where she has them stashed so if she doesn't want to dig them out I'll have to pass but maybe I can sweet talk her into it

But, you are right, that is something very important to know.

HH
Mike

 

[Mike Hillis]

I have based my discrimination assumptions on the F75 based upon my experience with the F5. And why not. They both use the same basic scale and share coin ID. I mean, a Nickel reads a 30/31 on the F5 and 30/31 on the F75. So I assumed that the gold ring range would follow suit.

Thankfully Rob has pointed out that my assumption was wrong.

Here is a nice little women’s 14k yellow gold ring I found with my F75. I use this as one of my bench testing items.
[attachment 338213 DSCN1271.jpg]
Here is a very thin 18K white gold ring I found. I also use this as one of my bench testing items.
[attachment 338214 DSCF0326b.jpg]
All things the same, my F5 will bench test the yellow gold ring with a TID number of 28, and the white told ring with a TID of 19. Now I have found a lot of gold rings with my F5 and a TID of 23 is a good cut off point for the majority of small 10k and 14k yellow gold rings. Yes I found some that hit below 23 but the majority were 24 and higher. So in turf areas with a little more trash than I want to deal with a disc setting of 23 was acceptable to me.

However, based upon Rob’s comment, when I tested the rings on the F75, the yellow gold ring gave a TID of 24, and the white gold ring gave a TID of 20.

That is a 4 point drop on the yellow gold ring. That is significant. In fact that moves a LOT of yellow gold rings below a TID of 30 if that same drop holds true. The bad thing about jewelry hunting is that I tend to sell them off ever so often when I want to buy something. I don't keep a stash of gold around other than a few test objects. So I can't go back and re-validate trends of ring TID on the F75.

It was also interesting that the small white gold ring didn't experience this same phenomenon. In fact it jumped a point. If we could get a little more info we might just be able to create a smaller notch for yellow gold rings on the F75.

I wasn’t able to retrieve my wedding band from its hiding place to test it. Maybe one of you will be willing to test your wedding bands on your F75 and post the TID numbers?

I’m definitely changing my turf disc pattern for small to medium rings on the F75. Probably start at 19 or 20 on the low end now. Not sure yet what the high end should be, but will probably start with 20 to 35 for starters until I get a chance to figure out the high side.

Again...wow.
Again...thanks Rob!

HH
Mike

 

[Rob in (Ca)]

There's a U Tube Video out there, where this guy air test 5-6 Gold Rings on The F-75.

all The Rings air tested in the foil Range......... it blew my mind....... some of the Rings were large

heavy set bands, that would ID well into the Larger pull Tab To low Zinc zone, on The other Detectors.

I now can't find the video, will keep trying

 

[REVIER]

Montgomery Scott...Starfleet engineer...
"I cannae change the laws of physics!".

I have dug 35 gold targets, a couple of chains, a few pendants but mostly rings.
I have dug them with a Compadre, a Vaq, an F2 and an F70.
Most I have air tested with the F2 and they all transferred over almost exactly to the same F70 numbers. Many were also tested on the two Tesoros and not counting small variances between the two brands they all came in at the same areas.
White gold comes in lower than yellow most of the time because of the alloys, those mixed with nickel especially but one comes in higher because I suspect it is alloyed with silver...both of those metals are used to make white gold among a few others.
The larger sized yellow gold comes in higher in larger items compared to smaller types, the higher karat gold items come in higher than lower karat of similar sizes and weights.

A friend in my old club found a tiny yellow gold ring on a club hunt and it hardly fit on the end of my pinky it was so small but still came in as a dime signal on his MXT and on my F2. Everyone at that meeting was confused because of the high range on such a small gold item but I wasn't...the thing was marked .999, pretty much solid 24k.

I laugh when I read posts from hunters that state or seem to think that most gold rings will come in at only specific areas.

"I have to dig all tabs to find most gold because that is where MY wedding band comes in"...same with nickel, foil or whatever else.
Gold jewelry items are not coin targets which are usually a standard size, standard weights and mostly made of the exact same amounts of of the same metals so there is no way to put gold into standard categories....that is like saying all cars are the same because they all have 4 wheels.

In reality gold can come in anywhere and everywhere but in my experience should be in similar areas on all targets without major number or category jumping....this is just physics and as Scottie always said...

Of course this is discounting the normal things we come across out there that affect and can skew our signals, masking, mineralization, depth and whatever else, I am only considering the actual and real conductivity readings out of the ground.

There are going to be slight variances, I notice my higher frequency F70 ID's targets slightly different than my F2 at a much lower frequency but it is not huge and only maybe one to two numbers difference on all targets at the most..if that.
Targets near the border of two sections could jump from one to another depending on the detector and programming differences but it still won't be a huge difference in numbers or actual conductivity readings.
Mostly though, gold is going to act within certain specific behaviors, specific sizes, shapes and alloys will come in at similar areas and in similar ways if tested under scientific conditions using detectors of any types or brands, even though they could come in different areas up and down the entire range from iron to the upper strata.

Again, my experience only testing my gold targets I dug on my 4 different detectors but in this case I have to go with what I have seen with my own eyes and my sense of logic plus my belief in those set in stone laws of physics.