Try the nickel test also from his website. You may remember these posts.
Hi Eric,
.... Want you to perform a unique test. Install factory coil (probably 8" coil) on the CZ-3D,,,, and air-test about 50 nickels in the "enhanced" mode. Write down (and keep seperated) the nickels that register as 'nickel' and the ones that report as 'round pull-tab". Keep them seperated. NOW........ install the 5" coil on the detector. Perform the exact same test. If only 1 or 2 nickels read differently..... the coil may be okay. If 3 (or more) nickels read differently... the coil is confirmed defective.
..... It already sounds like you have a confirmed 'defective' coil. BUT.... try this test also.
-----------------------------------------------------------------------------------------------------------------------------------------
I took 50 Jefferson nickles just now and ran a couple tests.
Test 1: Stock 8" coil
While in Enhanced mode, ALL read round pull tab, no exceptions.
While in Salt mode, ALL read as nickle, no exceptions.
Test 2: 5" coil
While in Enhanced mode, ALL read round pull tab, no exceptions
While in Salt mode, 37 read consitantly as FOIL, 13 jumped between FOIL and Nickle!
That last part was surprising to me, I would have expected all to read as nickle like on the 8" coil, not most as FOIL. The ones that read FOIL were very consistant, not bouncing around. The ones that read as nickle would sometimes jump to FOIL, but pretty much stayed as Nickle. I did notice that the 13 were newer nickles with very little circulation, the rim of the coins were still sharp and well defined.
Given these test results, what would you say?
Thanks for your help.
------------------------------------------------------------------------------------------------------------------------------------------------------------------
Hmmmm...... Sounds like we have identified TWO problems. The 5" coil certainly does not match the consistent results you acquired with the 8" coil. Imped. mis-match w/5" coil. Also, your CZ-3D is not calibrated properly. One Hundred New nickels (never exposed to dirt) should read/ID as "Round-Tab" 20% - 35%. All of the other new nickels (65% - 80%) should ID as "Nickel". This is normal for a CZ-3D in the "enhanced" mode...... when calibrated properly.
.... This prompts another concern. IF, IF, IF you have access to a United States "Half-Eagle" (( $5.00 )) gold coin,,,,, it needs to ID as "Zinc Penny" in the enhanced mode. This test will only test the high-end of the Zinc window.... and leaves the lower end (transition point) of the Zinc window as untested/unknown.