CZ coil question for Tom

Tom, some time back you explained to me that both the 8" and the 10.5" cz coils are very impedance stable/accurate. You also said that the impedance on the 5" cz coils is many times out of spec making them ID inaccurate.

My question is how common are bad 5" cz coils? Is there a significant chance that a new 5" cz coil would be out of spec?

Yes....... statistically ....... the 5" CZ coils are the most difficult to build 'impedance-matched'. Where you will notice it the most is: On a CZ-3D in particular........ see how the 5" coil ID's 'dug' nickel's........ as compared to 8" or 10.5" coils. I've had the ability to test a batch of 5" coils all at once. No two coils were alike (ID-wise). The delta/differential is not much; yet, really matters in the '3D' ID abilities.

I have not tested enough NEW 5" coils lately....... to be able to give a accurate answer!!!

Might add having limited use of several 5 inch coils they went deep as was able to raise sens. but depth readings were not always accurate and can give a large target alert on
large shallow coins...ID seemed to be accurate however only hunted for silver and pulled some 7-8 silver dimes near metal fences...Never used one with a CZ3D.

Thank you for that info, Tom. No two coils out of an entire bunch IDing alike is major inconsistentcy.

Apparently unit to unit quality variation is the hallmark of the cz-3d and the cz 5" coil.

CZ's are hand-built & hand-tuned....... and so are the CZ coils. When things are hand-built....... this condition is not uncommon.

Tom - IF you could get a set of coils (5", 8" and 10.5") "impedance-matched" from a supplier or factory, then had your tune up, would that address the problem? I had a detector I bought several years ago and sent my full suite of coils into the factory (not Fisher) along with the control box. They found/tested a suite of coils that were "impedance-matched" and made sure the control box was in calibration. It's depth is good for its class of detector, and the ID is consistent from coil to coil. Just wondering if that's too much to ask. Personally, I'd pay extra for that service on a CZ-3D. BBJ

Yes...... the problem would be addressed. Finding a pair of 8" and 10.5" that are impedance-matched..... is easy. It's that little 5" coil that has some variances. And...... once the 5" coil is built/set....... it can not be changed. (Same with the 8" and 10.5" coils........... once the potting epoxy has been poured...... the coil is 'fixed'..... and can no longer be tweaked).