The AF23C is a round-shaped 9" diameter Concentric coil for the Kruzer and Anfibio models.
The KR18C is a round-shaped 7" diameter Concentric coil for the Kruzer and Anfibio models.
I have owned them both and was very familiar with the 7" Concentric as it was my favorite 'General Purpose' coil on my Impact [size=small](that was stolen)[/size] as well as on the Racer 2. Even his day the 7" Concentric stays on my Racer 2 'full-time' as it is a very versatile search coil for day-to-day detecting, and especially when Coin Hunting in and around picnic sites and other places where I encounter a lot of Bottle Caps. It also helps in Relic Hunting type sites with a lot of rusty tin and tin shards.
Don't get me wrong, I am not against using Double-D coil and I have been since 1971 ... on certain makes and models that perform well with a DD coil based upon the detector's circuitry design and the type of site challenges encountered.
Most places I choose to hunt have very dense trash, especially ferrous-based junk, and I have favored smaller-size search coils since '71, and using them since '68. By 'smaller-size' I include coils of about 5" to 6½" diameter. My 2nd most-used search coils are those that are when I call 'mid-size' and those would be coils in the 7" round to 5X9½ elliptical or 9" round size range. I have a round 9" coil on one of my other make/model detectors, so I used that unit with 9" coil and my Racer 2 w/7" Concentric coil along with a 7" on a Kruzer and 9" on an Anfibio for comparisons for Coin Hunting urban sites as well as searching a more open WWII Internment Camp and another POW Camp. For comparison, since the 9" was a new coil offering from them, I
After a week of detecting time and comparisons, I found that I was just fine with what I already had for comfort and balance as well as performance. I didn't care for the 9" compared with two other 9" round coils due to the weightiness, and the rod-mount location being too far to the rear from center. That made the newer 9" Concentric feel too nose-heavy and poorly balanced, at least for me to enjoy making use of it. Also, I preferred the 7" Concentric coil's feel, and also liked the better handling of rusty washers, and Bottle Caps over the 9" Concentric.
I have generally found a round-shaped Concentric coil to handle Bottle Caps / Crown Caps a little easier than a common-size Double-D coil, but even that can vary based on the coil size and configuration combined with the individual metal detector brand / model circuitry design. While a smaller size to perhaps a mid-size Concentric coil might have some advantages handling ferrous challenged targets. I've also favored more of the older analog models over using some of the modern digital circuitry-design models. I reached my conclusions about a year ago and haven't had a desire to change.
So, I favor the 7" Concentric for the reasons mentioned: Lighter, better balanced, more comfortable. and does a better job, in my opinion, handling those Crown Caps. But, like I said, 'that's me' and I know some folks who like the 9" Concentric because it works for them.
Monte
