Another 4 hours with the F70.......

[BarnacleBill]

in an open low trash beach area for two hours, then some iron dirt hunting for another two hours. And the results are squadoosh. No deep targets in a low mineral freshwater white sand beach, the usual clad culprits shallow. Even tried Slow Mode, nada deep. And I know that there's a whole bunch of stuff deep on this beach. In the iron, nothing but noise, no masked targets revealed.

After four hours my ears had enough. Got out the Edge, started pulling targets out of iron within five minutes. I believe I grow more fond of Dimitar's design with every passing day. Real time display of rejected iron ID's on the Edge is just killer for wading through iron.

HH
BarnacleBill

 

[Jackpine Savage]

was also poor and to make matters worse it loved iron on those beaches as well. However that was the only area it fell down in. You can bet I let DJ know too!

Tom

 

[Mr.Bill]

I'm in a real low mineralized area, and the T2 has very good depth here. I'm sure you don't remember, but I had brought that up a few times when I started handling them. I was just surprised that it did so well.

Must be something going on in that area where you hunt, that affects the signal enough so you notice a loss of depth.

 

[BarnacleBill]

Well it's disconcerting for sure. From much of the forum posting the F75/F70 was supposed to be able to leap tall buildings(incredible depth, faster than any detector on the planet, opens up hunted out iron/trash areas, etc etc).

Being that it comes equipped with a concentric coil I wanted to make sure that I gave it a fair shake over very lightly mineralised areas, so that there would be no question of asking more of it than it's capable of over nasty ground. This would/should also alleviate issues of chattiness from mineralised ground, or ID stability. I do have areas where your coil will melt if you touch the ground with it.

The top of this beach shows a consistent GB of 75, and down in the wetter sand a GB of 83, with no Dirt Bars showing in DE mode with a sensitivity of 80 and zero threshold. These appear to me to be pretty tame settings on a fairly inert beach. If SL mode is used then it will show one dirt bar and nothing above that. I do have a Touchstone on this beach, which is pretty funny to show people, that I test every detector against. A football sized piece of Basalt that will send a detector into overload with the coil at about six inches. And the F70 reacts just like all the other detectors I've tried on it.

While operating in DE mode a strong iron return will light the lowest dirt bar which is helpful, but no where near as handy as the continuous readout of the Edge/Excel, where you can immediately see the cause of a possible iron false. I've yet to use a detector better than those twins for working quickly and efficiently through iron, without having to stand there and work the coil from five directions deciding whether it's iron pulloff or a good target being masked. And the F70's susceptibility to pulloff/edge falsing is so high that an inordinate amount of time is spent analyzing every click, pop, & wheeze. A small DD for the Excel or Edge would park a lot of detectors in closets if they were able to make the design still reject iron as well. I've taken Barnacle Jr. out a few times equipping him with the Edge six inch in bottle cap Helll, and he has whipped my buttukus, despite a lack of experience and not so good coil technique.

So next outting the F70 is headed for mineralised cobble stone field helll! Maybe it'll work better there.

HH
BarnacleBill

 

[Mr.Bill]

Hi BB

I think you will find the F75 does operate different than the F70. Now I can't say for sure that under your conditions they both wouldn't act the same, but I would be surprised if they did.

They both have very good depth, rivaling the best out there. I can't speak much about the F70 in trash, but I can about the F75. The F75 with the standard coil on it does real good hunting trashy parks & playgrounds. It does well in cellar hole hunting also. Cellar hole hunting has a lot of iron. Haven't heard of a problem there.

In reality, although I have used both models a lot, it hasn't been a lot under those conditions. I like the F75 for field hunting, although the last time I had it out I used it on a very trashy ground area, and did not notice any problem like your having. Bill Ladd and myself were using 3 units, F75, T2, and 1270. We were hunting, and marking our finds before digging. We checked between each other, and that all did well in the trash & junk. They all had there stock coils on. The F75 behaved very well.

Bill, I'm like you. Had I noticed either the F70 or the F75 acting poorly, I certainly had the chance to say so many times.

Try to find a F75 to use first, rather than lumping both the models together as 1 in performance. Darn, if I had a used one I would send it to you for testing.

Have a nice day.
Mr.Bill, freezing his a++ off in chilly 39 deg. Cape Cod day.

 

[Elton]

Question please

You say the f70 loved the iron on your beach correct ?

I am not certain you were expecting the right results from the detector. I don't recall having ever read where the F70-F75 doesn't hit iron..I have always thought it hit the iron, but with the lightening fast response allowed one to find the targets normally masked next to or near the iron targets..

I also thought the discrimination up past 28, or 29 helped the iron problem. pick up...you didn't say if you did that operation..

One other question did you manual ground balance on the beach... or is that just a salt water beach that requires that.. I would think a concentric coil migh require the manual GB..........it would be hard to say whats under the sand you were trying to work.

I don't pretend to have your knowledge of detecting..nor Mr. Bills either..but was just asking....

EL

 

[BarnacleBill]

Hi Elton,

I think you have some valid questions which I will try to address.

The beach in question is a freshwater beach with mild mineralization and the F70 only has Auto GB. But GB isn't really an issue as the unit shows consistency in Ground Balancing, and I also in an earlier post using ferrite samples mapped it against an X70, and the results are as expected.

In regards to setting the Disc higher than 15, well that's a problem which I will answer by relating what occurred during my outing. Right after I switched over to using the Edge I began re-tracing my footsteps in the sand. This is easy since it's winter time and there's very little activity with smooth sand covering most of the beach. After traveling about 40ft I arrived over an area that I know has some old buried chains that are tied to a buried concrete block used to tie up boats. There are 5 to 6 of these chains splayed out like a fan towards the water. I always test new detectors in this area as it shows iron rejection/filtering ability, and without doubt there are good targets hiding around them.

As I arrived over the spot I could see the Edge indicating iron with a variety of negative numbers as expected, but within a few seconds I got a weak audio report and saw a (+) positive number flash by. So I slowed down and isolated a weak low positive ID. What came up from no more than 2-3 inches down was a small brass ferrule that looks like an insert into a wooden or plastic lure, as it had about a foot of heavy leader fish line still attached. In the picture below you can see the ferrule on the right and on the left a gold medallion. On the Edge both ID at 6 and on the F70 both ID at 20.

[attachment 120625 Ferrule.jpg]


And therein lays the rub with running the Disc up to around nickel to get rid of the iron falsing. As primarily a wader I am trying to pull foil(small gold) out of iron. And that task is made difficult by detectors that don't have excellent iron filtering, brick wall response as it were, which is a common term used in filtering.

You can have all the speed in the world, but if noise comes along with that speed you've gained nothing but Audio Masking and fatigue. I've seen several individuals make the comment that they can take the F70/F75 out in their driveway, and lay down three targets close together and swing as fast as they can, and it will hit all three targets and report them. Well that's a cheap parlor trick of absolutely no value in the field, because we're not hunting surface targets that we can see.

Did the F70 report the ferrule when I passed over it, most likely yes, but it also reported about a dozen other responses from the chains at the same time. So the F70 may be able to overcome Target Masking to some degree because of it's low lag time, but at the same time it creates another form of Target Masking, which I've termed Audio Masking, because of the iron falsing. Is the F70 the only detector I've used that exhibits the same kind of behavior, no, there have been a few others.

Below I've illustrated what occurs with Audio Masking, and shown the little ferrule as a gold colored rectangle, and the green audio response as the valid one.

[attachment 120626 chain.gif]

And so I'll keep playing with the F70 trying to identify it's weak & strong points for my type of detecting.

HH
BarnacleBill

 

[Elton]

I can see why if thats the case, you would not be happy with the F70 on the beach.. Thank you.
Appreciate the valuable information..

 

[Mr.Bill]

Thank you for the great description, and graphs. There's no doubt the "Edge" has the edge. But I needed to go try out a F70 under your conditions. Perhaps you could help ??

I don't have any buried chains to test over, but I do have a test garden set up with a lot of nails, and rusty bits of metal in it. I have a few random placed clad coins mixed in with nails. What I did was discriminated all the way up to below 10Cent marker, and had sensitivity on #60, everything is as the F70 come out of the box. It hit's on the buried dime quite loud in one back n forth direction, and so, so back n forth the other direction, (doing X). The ID range is bouncy in the upper numbers, but the audio is good. Good enough to cause you to stop & dig it in the field. I decided to crank up the sensitivity to max, performed the same as far as the iron, and the coins, just increased range.

I tried it by lowering the discrimination to iron elimination only, say number 10. It was not noisy, and the detector performed OK.

Lowering the iron discrimination down to number 1, now that was really noisy, but one could still tell the good high target sound of a coin.

One thing I did noticed was the need to slow down my sweep speed considerably, with all settings over the iron field. I also could not use the pinpoint or all metal mode. Pinpoint was near imposable, and all metal would drive you nuts.

I will say I have not taken it to the salt beach to try out like this.

So I don't doubt that passing over the chain, and having a good target near by you may miss it. I don't see it happen in normal conditions. Even what I just tested at is under unusual conditions.

Is there a way I could duplicate what going on with you, without driving to your area ?

Did I mention I still would take the ID Edge over the F70. I do like it better overall.

 

[BarnacleBill]

Thank you Mr. Bill for making that effort, I do appreciate it. What I think I'll do is print out what you've done, go back to the same place, bury some targets in a clean area and see what happens. Then I'll move them to a iron-ee area and try to duplicate what you've done. I'll scribble it all down using the sharpest crayons I have and post the results.

Thanks once again.

HH
BarnacleBill

 

[Jackpine Savage]

Double D.... and no, I don't mean Jane M

 

[Jackpine Savage]

FT really needs to bring back Dimitar, put him in a room by himself and let him have at it with his fresh thinking. With Jorge's circuit design ability and the advanced software techniques DJ has developed this would be a perfect marriage.

JMHO
Tom

 

[Mr.Bill]

Hi Tom

Unfortunately I can't see that happening.

He really had different thinking about metal detector circuits, and they worked well. He came to New England to work with Bill Ladd on the ID Edge. He was interested in making sure it did what he thought it should.

 

[Jackpine Savage]

Are you disc'ing out all iron? If the 70 is at all like the T2 you gotta set the disc down in the iron range for best results. Find a point where the falses are bearable and go for it. Again if its like the T2 that's just the way they are designed to run.

Also, Don't rely on the first GB you get over a nearby clean spot. Re GB as neccessary if the falsing is bad. It may be a PITA to have to do it, but it can sometimes help.

Tom