Need help with the LTD

I have the Fisher F75 LTD and use it for relic hunting and love it. I found my first mercury dime last week and that sparked my interest in coin hunting. I went in the back yard and used all metal to find 3 clear spots and buried 3 dimes. One at 6, 7 and 8 inches in different holes. I dug a plugs about 6" across and placed the dimes in the bottom and packed the dimes with dirt and replaced the plugs and packed. I know test gardens have to age for a few years to become valid test but here is the kicker. With the LTD I can only hit the 6" dime, nothing on the 7 and 8 inch. I have tried all the setting i can think of. I would expect BP 90 sens and 0 disc to hit all three but nothing on the 7 and 8. I put the 5"DD on and got the same results. Now for the kicker, I went and got my Dad's fisher F2 and it hit the 6 and the 7 inch dime. How could the F2 hit that 7 inch dime and the LTD not get it? Help! Randy

what kind of soil conditions? Is area clear of ALL iron even flakes? Don't have an answer just trying understand all the variables.

Jamt225,
I don't know about the flakes but I ran the LTD in all metal until I found 3 spots that were as clear as I could get. Soil conditions are moderate. Ground balanced at 54 and fe meter at .03. There is also some EMI present but not unbearable. I don't have a magnet for flakes. Still don't understand why the F2 could get it and not the LTD. Thanks Randy

I'm still a student but Tom should have some clues. We''ll see what he says.

While in bP mode you might try raising the coil a couple of inches over the ground instead of scrubbing the ground. At that sensitivity level the feedback from any ground mineralization or iron flakes could be affecting the F75 LTD. Raising the coil may lessen that affect. Also a steady sweep speed (not too slow) is important. Did you try DE or JE modes?

dgc,
I tried all the modes, and have spent several hours over these targets trying everything I can think of. Believe me this does not stop me from relic hunting with the LTD but when I am stuck at home it is good to try things. I also put the 6.5 concentric on with the same results. I would never have even posted this except for the fact that the F2 hit 2 of these targets. Could it be the lower frequency of the F2 made the difference on the small high conductors and maybe the F2 is not as sensitive to flakes ect.? There are so many variables here, and I know folks shy away from these kinds of questions. Here is what I am going to do, pick another part of my yard, as far away from EMI as possible, get a magnet and sanitize the area and try this again. With my schedule this will take some time. Thanks for the help. Randy

Yes, time permitting, try a different area..........just in case silent masking is taking place.

I think fresh planted coins may not work as well..if I remember right Tom said the CZ3 was the same when the maytrix is broken the target may be missed. If you had a test garden that was done the right way and you came back months later then you may have hit the target but I would send the machine back in and let fisher test it.

LowBoy

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OK Randy, sounds like you tried everything. For what it's worth, I have ground conditions very similar to yours (GB 63, Fe3O4 .03). I have a clad dime buried at exactly 8.5 inches and my F75 LTD hits it. I will admit that I have to be directly over the dime to hit it. If I am off the mark too much, it doesn't hit it. I'm beginning to think you may have a detector problem. I'm like you, if the F2 hits the dimes, the F75 LTD certainly should. Good luck.

Yea, I think it is going in to the shop. Today I got my daughters F4 and the 6 and 7 inch dime with a good signal ( and good VID) and a faint signal on the 8, so the LTD needs some attention. Thanks for all who responded and I will give an update when the LTD is fixed. Thanks Randy

Make sure that your F75 will air-test a clad dime to approx 1-foot. If it does not.........you found your problem.

Tom,
I finally air tested the LTD tonight. I first tested with factory presets 60-sens and 15 disc in BP mode. I got 7.5 inches on the clad dime and 10 inches on a clad quarter. I then cranked it up to 90-sens and 0 disc and it added 1 inch to both the dime and the quarter. Thanks Randy

Hmmmmmm. I'm not happy with only 8.5" on a dime when your LTD Sens is '90' and Disc is '0'. I think we found the problem!

So what's the next step Tom?-----If sent in to Fisher, can (will) they "fix" the depth problem?--------Del

Del,
I talked to Felix at Fisher and he said send it in. Maybe it just needs to be calibrated?? I will let you know how it turns out. Randy

I also had a couple of other issues with the LTD I discussed with Felix. Sometimes the fe3o4 meter will max out and stay maxed out in an area where is shouldn't and I will have to do a factory reset to make it go back to normal. Also, sometimes when doing a fast grab ground balance it will make a constant high tone no matter where you do it, like you are pinpointing over a big piece of metal. It is like the overload during gound balance as discussed in the manual but it is not over metal. This has happened several time in my back yard where there is no metal in the ground and I have to do a factory reset then it will ground balance ok in the same spot. I have also noticed the ground balance will be off at times. My back yard will usually ground balance at about 55-60 all over the yard but sometimes it will balance at 45. If there is something wrong in the ground balance part of the detector could this be the depth issue as well???



Edited 2 time(s). Last edit at 05/03/2010 04:20PM by iskirkra.

No, I think this is secondary (effect.........not 'cause'). It might be something simple......like a bad coil (coil wire). Yes, Fisher should be able to fix this.