I bought the Discovery 3300 right after it came out. I also purchased the 4" 'Gold Nugget' (sniper) coil and the 10" 'Magnum' coil. I was instructed by Maggie Lazo of First Texas (parent company to Bounty Hunter) to send in the unit with all three coils, then the coils and control box would be 'calibrated' by BH. When talking to the technician working on my machine, I found out that 'calibration' is matching the resistance value
(not sure which pin-to-pin locations are checked to determine values) of all 3 coils to each other and the machine. In short, they swap out 4" and 10" coils until they find one of each that matches the values measured on the 8" coil supplied with the detector. The service is free. All you have to pay for is the shipping to the factory and BH pays the shipping back to you. It's treated like warranty work.
The benefit to this is that the unit will ID correctly (TID, VDI, depth, etc.) with all three coils. For example, the 10" coil that I purchased when I bought the detector was almost unusable with the 3300. What I got back was a detector that was checked over by the technician and returned with 3 perfectly matched coils that perform equally well on the unit. The unit is very stable, all information on the display is very accurate down to 8" or 10" depending upon soil conditions, and is a joy to use. I have a lot of confidence in my 3300.
I also had the upper stem upgraded for $20 to the same one as found on the Land Ranger or Time Ranger with the locking collar. The locking collar keeps the lower stem from wiggling around inside the upper stem. This wiggling can cause the coil to be jolted around at the end of the swing, causing a false tone, something akin to bumping the edge of the coil on a hard surface which will also cause the unit to false. While I've always had a hankering for a fully kitted out Time Ranger, the 3300 has been good enough to put off an upgrade. Hope this helps. BBJ
