F2 8" Coil compared to 10"

[msobeski]

Can anyone tell me if it's worth the change to go to a 10" coil? Is there any depth difference, I have read that there is less emi interference with the 10" Wanting to upgrade gradually due to still learning.

 

[salmonriverhotrock]

This is about the best way I have seen it explained below. A 10" used hunting some of my area along the Salmon River would be a disaster. For the over 50+ years people have put aluminum cans and foil into camp fire rings and pits, the millions of melted blobs and tiny beads have unfortunately migrated out from them and are all over, even in the river bottom. I don't even bother to pick the stuff up because you would insanely be there forever trying to find and throw it all away. Keep in mind that a concentric (round) coil the larger it is, will be more surface area effected by ground iron or mineral content where an elliptical DD coil being more long than wide only searches in effect, an area something like a long slice so is less effected by ground. They both have their day in the light and then have their failings depending on use. If a guy has a wallet thick enough, I would have one of each coil for my F2 but right now, the 10" is the only I don't have and mainly because most areas here are so trashed out, it would be very difficult to use without Notching or discriminating out a lot of stuff. Something else, the larger the concentric coil and the more ground iron or mineral content, the less effective the coil. A lot of Gold Nugget hunters have gone to Pulse Induction machines with large coils because the VLF hunters have pretty much cleaned out the detectable depths they are limited to because of ground effects.

The "rule of thumb" governing larger search coil use is as follows: "as the size and depth of the target you seek increases, and the concentration of junk targets in the search area decreases, the size of your search coil should increase."

 

[msobeski]

Thank You for saving me 60.00, it is really appreciated. I will wait till next spring and buy a butterfly one. Thanks again, very well said.

 

[REVIER]

In areas that are wide open I have used my 10" coil and even though I don't have that many hours with it, it does seem to go a little deeper than that 8", and get a little clearer signals and targets 4, 5, 6 inches or little bit more.
In my experience, mine does seem to be a little bit less susceptible to EMI, although it still is affected, some, and the area of pinpointing does seem to be a little bit bigger but that is really no big deal.
I already have a very large DD coil on my the Vaq so I never saw the need to buy one for my F2.
I I also don't like the fact that all DD coils seem to have a problem with the bottle caps, that is something you have to deal with no matter what brand or detector you use.
I prefer to use concentric coils for the most part, and since I hunt trashy areas more often than not, the small sniper coral is my favorite coil and is mounted about 98 percent of the time.
That small hockey puck oil is one that I would suggest everyone have in the arsenal when they own an F2.
Great target separation is a given and fantastic with the F2 and any coil, but the best one to use when you need surgical precision is going to be that sniper.

 

[salmonriverhotrock]

Now I would not ditch the 10" concentric coil all so quickly. There is an old trick you can use with coils being overwhelmed by ground and or multiple targets. Envision a cone shape detection field under your concentric coil. The rule of thumb is your detection depth is at or around what ever the diameter of the coil. The detection field will be widest at the coil and come to something like a point lets just say 10" down towards it's end. Now, If you encounter multiple targets with the coil about an inch or two off the ground, simply raise it how ever much required and your detection field becomes smaller or in effect, a smaller coil. This can also be used if the ground conditions are overwhelming the detector ground balance and Gain/Sensitivity (power). I myself do plan to buy a 10" coil for my F2 because there are other places it would be more practical and beneficial to use and would get a little more depth than a DD coil as long as the ground interference is not too bad. Heck, I have used a BH Pioneer 505 with a stock concentric coil to find buried or missing highway culverts a good 5 or so feet deep but I knew how to trick the machine into doing it.