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Some information on the new 11" Biaxial coil for the F5 :clapping:

M

Mike Hillis

Well-known member
I've been testing the 11" DD coil for the F5 for over a month now. Fisher has production up and running and quantities ready to release so I've been giving the go ahead to share information about it.

What follows is a lot of info. Enjoy.

EMI:
For shielding I used a real simple bench test indoors. Consist of turning on a lot of electrical appliances like the tv, ceiling fan, lamps and activating the thermostat on the refrig air unit. Threshold at minimum, Gain at Maximum. Raise the threshold until it picks up intermediate chatter, then continue until totally unstable.

In Disc mode
Stock coil went intermediate at -2, went unstable at -1.
11
 
Excellent information, Mike. Thank you.

Are you also testing or will you be testing the upcoming 5" DD coil for the F5?
 
Wow Mike! It sounds like you live in metal detecting Hades. Good report. BTW I went with the Omega but still watch for your posts.

It sounds like the new coils will soon be out as Nasa Tom has given a report on the DD Omega coil too.

blacktoe
 
Hi Marcomo.

I was told that they would be sending me a 5" DD to test. That was before I was contacted about testing the 11". :shrug:

HH

Mike
 
Thanks for the information about Tom's Omega test. I hadn't seen that. Tom's ground is virtually mineral free and he gives great iron trash feed back. I'll either be getting a 11" DD for the Omega or having the F5 coil reconfigured to plug into my Omega to see how it does in my ground. I was going to swap the connectors myself but I was told it wasn't a simple switch out.

I envy the guys with the good ground conditions. They only have iron trash to deal with.

HH

Mike
 
Great info I think the 11 DD will make the F5 a great unit for all types of hunting it could be the best bang for the buck it is really fast. I have tried out the 5 DD for the F75 in the gold country of Calif and it is fast not as deep as the 6 inch but for relic hunting in bad masked ground I think it will do just great. All I need is a little larger coil like a 15 inch. Thanks for the info. Good job!
 
Thanks for the tests Mike.

Somewhat odd and disappointing results on the F5 DD IMHO. I anticipated it to be more accurate, and more stable being that theoretically a DD should see less ground, with less to analyze (although you did pick up processing speed).

I suspect the DD sensitivity reduction to small objects is due to having the run the threshold in the negative. Looks like a balancing act between the sensitivity and threshold, but with some negative implications depending on what your hunting for. If you just want depth, you may be ahead of the game (vs using the stock coil), but if you're jewelry hunting and trying to catch small targets like chains, small ladies rings, etc., then you're probably better off with the concentric coil. Interesting results, although I'm not inclined to add the 11" DD to my F5 from these findings. If one lived in an area with less hot soil, I suspect the tests would pan out much different.

How does one get on the Fisher test team?

hh,
Brian
 
Hi Cal,

Yep, you picked up on that. Traditionally I would expect to see less ground minerals with the DD coil. I too, was really expecting the ground mineral reading to drop with this coil. What I suspect is happening is that the increased transmit power of the F5 is overriding any advantage the DD coil in this size range provides. So if you typically hunt 4 bar FE ground you won't see much improvement other than ground coverage and target separation speed increases.

If you typically hunt 2 bar or less FE ground you will see improved depth, id at depth, as well as target separation speed increases. In 2 bar ground I regularly exceeded the stock coil performance.

What I really want to see is what the 5" DD does in 4 bar FE ground.

HH

Mike
 
I've been very impressed with the 5" DD on the F70. I tested it at a park with very tame dirt (one bar on the F70), and was able to run the sensitivity maxed out, and the threshold anywhere from 0 up and it was completely stable, killer on nickels, with great target seperation and better TID the the stock concentric. The only limiting factor I saw was that it maxes out around 6" of depth (for a 5" coil that's still good), and of course a large reduction in ground coverage, but perhaps not in a sense, as it's more stable with less falsing, so you spend less time examining erroneous targets.

I finally ordered the 11" DD for the F70 from Richard @ Backwoods, so I'm keeping my fingers crossed that I'll see similar improvements to the 5" DD but with much better depth. The stock concentric just sees too much soil, which in mineralized or trashy areas has been a problem.

hh,
Brian
 
Mike - As someone whose soil reads 2 FE bars the vast majority of the time with the F5, I'd be curious if you could give an idea of how much performance improvement you saw with the 11" in similar ground.

I'm not in a position to get both right now, so I'm wavering on whether I'm going to get the 5" or 11".

I do a lot of detecting in high iron areas, so target separation and unmasking capabilities are paramount, but the additional depth is a very important consideration too.
 
Don't you also have the F75 ? I was wandering what the difference in performance was between the two and also the F5 if you have used all three.
I was thinking of moving up to a f70 from my f5. If i can get the same punch from the f70 there would be no reason to lay out the extra bucks for the f75.
 
Terry in PA said:
Don't you also have the F75 ? I was wandering what the difference in performance was between the two and also the F5 if you have used all three.
I was thinking of moving up to a f70 from my f5. If i can get the same punch from the f70 there would be no reason to lay out the extra bucks for the f75.
Click to expand...

I don't have the F75, I have the F70 and F5 (and F4 & C$). So far I like the F70 more then the F5 as it goes deeper for me, but not by much. I also feel the TID on the F70 is better then the F5, the F5 is pretty wishy washy on nickels and pulltabs (effectively fisher has dumped them into the same TID zone IMHO). I do feel the F5 has a superior interface and is more ergonomic. I have the F75 11" DD on the way for the F70, which I hope will give me the depth I'm looking for and make the F70 more stable. The little 5" DD is a great coil, but due to the small size the depth on small coils seems to be limited to around 6". I recently an area that I know has been pounded by both Explorers and F75s and in hot little area they've pounded I was able to pull a 1912 wheatie, a 1910 Barber and an old Victorian era heart locket they missed with the F70. The wheatie I found with the small DD and the Barber and locket I found with the stock F70 coil.

If the F75 11" DD performs like 5" DD the F70 should do real well were I hunt. By all accounts I've read the F70 is on par with the F75 in depth, but the F75 does have a few more features and is a little more ergonomic (and you have to love the trigger, this should be standard on ALL metal detectors IMO).

hh,
Brian
 
Hi Marcomo

In the 2 bar sites I was finding deeper coins that I had walked right over before with the stock coil. They id'ed stable numbers with clear audio. There could be a couple of reasons for this:

It could have been I completely missed getting the stock coil over it because at that depth the sweet spot would be only the size of a golf ball using the stock coil. The larger ground coverage could have been the missing link.

It could have been the result of the settings. The stock coil and the 11" DD coil are not parafocal (to borrow a lense term). You can't just switch them out and keep the settings the same. They each have to be set up differently. I find myself wanting to run the 11" DD with a higher gain setting than I do the stock coil.

I focus mostly on the 4 bar results as that is what I'm hunting most in. Next time I get back there or another 2 bar site I'll do some more comprehensive testing so I can give a more detailed account.

Deepest coin recovered with the 11" DD in 2 bar ground was a clad quarter that was somewhere between the 8" and 10" mark. Nice high tone in the 4 tone mode and gave a pretty stable quarter id with numbers staying between 80 - 86.

HH

Mike
 
Mike Hillis said:
Deepest coin recovered with the 11" DD in 2 bar ground was a clad quarter that was somewhere between the 8" and 10" mark. Nice high tone in the 4 tone mode and gave a pretty stable quarter id with numbers staying between 80 - 86.

HH

Mike
Click to expand...

That Mike is very impressive :clapping:
 
Cal,

I was supprised to see a quarter come out of that hole. I thought I had a silver ring.

HH

Mike
 
Cal_Cobra said:
Mike Hillis said:
Deepest coin recovered with the 11" DD in 2 bar ground was a clad quarter that was somewhere between the 8" and 10" mark. Nice high tone in the 4 tone mode and gave a pretty stable quarter id with numbers staying between 80 - 86.

HH

Mike
Click to expand...

That Mike is very impressive :clapping:
Click to expand...

Yes he is! :rofl:

Seriously, thanks Mike for your response to my question and the info you've shared about this new coil.
 
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