I'm not personally opposed to aftermarket searchcoils, it's a simple fact that the economics of accessory searchcoil design and marketing tend to favor small independent producers provided that they know what the heck they're doing. Which doesn't come easy, half of what goes into an induction balance searchcoil is voodoo and black majick. What puts huevos rancheros on my breakfast table isn't accessory searchcoils anyhow, it's metal detectors. Factory accessory searchcoils are a very small part of our business. .
Sometimes an aftermarket accessory searchcoil is so good that people buy a particular make & model metal detector in part because of the specific aftermarket searchcoils available for it. Back when Karbowski was still alive, he made "bigfoot" and I think "littlefoot" searchcoils for certain White's models. And it helped sell those models. White's had their own reasons for not wanting to make those same searchcoils, and (without saying why), I agree with their reasoning on that. It was not and should not have been a factory searchcoil. ...... I tried to twist their arm to stop thinking of Karbowski as a competitor and start regarding him as an ally. To my amazement, White's wasn't having any. Jimmy Sierra, bless his opinionated and stubborn heart (love the guy, but there were moments it wasn't easy) was a smarter fellow, and behind the scenes did his best to make sure that the things that needed to happen for everyone's benefit did happen.
In general I don't comment on specific aftermarket searchoils for several reasons.
1. I don't know anything about the specific searchcoil in question.
2. If I do know a thing or two about it, and like it, saying that I like it could look like an endorsement of the product, which amounts to an endorsement of the company that makes it. Then if someone buys it and runs into a problem, they blame me for misleading them. It just ain't worth the grief.
3. If I do know a thing or two about it, and don't like it, then I'll be accused of dissing the product because "it's a competitor". Another "It just ain't worth the grief" situation.
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And, on that other subject, time for a fogey reminisce. I really miss working with Jimmy Sierra. One of the smartest people I've ever known, and most of the time kycke-arse fun. And when things had to be nuts-and-bolts serious, he was all business, a very good trait as well. This industry has been remarkably good to me, and working with Jimmy Sierra was a several-years high point. The GMT/MXT platforms Jimmy and I developed about 15 years ago are still among White's biggest sellers.