I have been using the NEL Thunder for the Racer 2 for the last few months. This is my first large coil so I am not sure if my experience is for all larger coils in general. What I expected based on research to larger coils in general was:
Greater Depth
Less sensitivity to small stuff
More prone to EMI
Heavier and harder to swing
I certainly got the greater depth. Exactly how much deeper than the stock coil I am not sure. But I was pulling out deeper targets at my usual spots that I have hit hard before. I think my deepest quarter sized coin was just shy of a foot in mild soil. This coil is definitely NOT less sensitive on smaller target! All all my usual sites I was finding small stuff all over the place that hit hard. On the first day out with the Thunder at one of my most hunted out sites (old soccer field; basically now cleaning up foil signals) I found 2 small chains and a bunch of other clad coins. All the targets were not very deep but they seem to be far more corroded than usual and at odd angles; slight off on edge at 10-15 degrees). The small silver chain's clasp was a very solid target and I thought I would end up digging yet another copper rivet. I was also digging a bunch of other small target like rivets and shoe lace eyelets. All this was done in a corner of the field I had hit the hardest. It's the area I enter the field, turn on my machine, ground balance and head off in one direction and when I finish for the day I return to the same place still swinging. I honestly though there was nothing left but low-mid foil signals. I have hit this patch with the stock coil and the 5" coil with various settings. The images below show the result of a 1.5 hour hunt in the small area. Not exactly hunted out....
The US dime is there for size comparison.
The second time out with the Thunder was a lunch time hunt at a house site with a small level lawn. House was built in 1848 and I have also hit the lawn hard using DI3, DI2 and ALL METAL. This is the place I go to to test any new detectors or coils I buy. Again as far as I was concerned, only a few low foil targets and iron was left. Takings for the day was few foil balls, 2 pull tabs, 2 modern clad coins, one small old bronze coin and one small silver 1945 King George VI Silver coin. The silver coin left me speechless. I had never recovered a silver coin from this lawn before! It was hiding among iron and one side of the coins was actually stained with rust. The VDI reading was lower than usual but the tone was solid with iron buzzing around.
My third site was a house built in 1925 of which I have also hit hard. This house is midway up a hill with two very large telecommunication towers at the top. EMI is terrible and even with stock coil you will find it difficult to use ALL METAL and DI2 mode unless GAIN is lowered to somewhere around the 60-70 mark. With DI3 I could crank the GAIN to 90 without too much problem but machine was sparky. The front lawn here is littered with rusty nails. Slowly griding the lawn I was rewarded with a few more clad coins, 2 buttons, one of them very rare and another silver coin, a 1915 C. Brooke Rajah 5 cent piece. Again I have not found any silver coins at this site before until now. I was running DI3 and the coin gave a tiny pip of a signal... like a rivet. It did not have large iron around it but it did have a lot of small rust fragment all over the bottom of the plug where the coin rested.
This coil seems to amplify mediocre targets to a more dig me signal. You get good target revealed but also trash. One of my sites is an old rugby pitch where there are lots of trash and good targets that can also be very deep. Honestly, it was more difficult to use the Thunder here. Not because there was a lot of solid trash target like pull tabs but because the ground is littered/contaminated with all sorts of smaller tiny fragments of metal that hit in the high iron to low foil section. Reducing the GAIN helps a lot but also looses depth where the old coins are in this field.
Weight, it was slightly heavier than the stock coil but honestly, it was not difficult to swing at all. Although my hunts on average lasts only between 1.5 - 2 hours.
EMI, no more worse than stock.
No problem ground balancing.
The coil creaks where it attaches to the rod when you swing. Not a problem for me but might drive others nuts.
Coil cover does not fit too snug with the coil. I used duct tape at four corners to secure the cover to the coil just in case the cover flew off with some over enthusiastic swinging.
VDI reading of known targets did not change, BUT there was a more noticeable bouncy VDI readings. For example with the stock coil a local small clad coin that normally reads 20 on the VDI near the surface would read 17-21 when deeper in the ground deeper. But with the Thunder, that same coin at depth might read 14-23! And that same coin at an extreme depth like 9" have tricked my Racer to give a choppy high tone!! But with the stock coil that happens as well at depth. Racer loves foil....
I also think that the additional items I found was caused by me overlapping my swings more as I was using a larger coil but was too set in my swing style of using the stock coil.
But there is no mistaking its ability to find small stuff. It's shocking.
