UK Brian said:
Sold as the worlds most advanced detector back in 1985. Seven coils both Co-Planner and Co-Axial types. Bloodhound deep seeker hoard hunter attachment. Also coils with 9 to 50 feet of cable. Six 9 volt batteries to provide power. Automatic battery check. Semi-automatic tuning did away with the need for mercury cut out switches. Salt water mode and really deep all metal mode.
The ADS (automatic detection system) switch on the handle (if you haven't got the instruction booklet) is multipurpose. Press right and release for VLF discrimination mode, press right and hold and TR discrimination mode is activated. Each movement retunes the detector. If the VLF/TR panel switch is flipped the ADS handle switch swaps the VLF and TR operations over.
Still work better than many of the cheaper motion machines of today with the drawback of being fairly heavy on batteries and the weight which was going on 5 lbs even with the stock 7.5 inch coil.
The ADS 3 also had pin point and depth reading. You press the toggle to the left and hold for these two options.
You also see on the panel a screw head with no knob marked audio. It is your "NULL" set. That is what sets your threshold. You also have a knob that adjusts the tone too your ears liking.
I have forgotten the exact procedure for ground balancing. But you can get that from Garrett either on their web site or by phoning them. If I remember correctly, you hold the detector waist high, hold the toggle to either side getting the threshold and pump it like the current model detectors. It has a 10 turn ground balance switch. Be sure the tuning selector is in the manual position while you ground balance. The "NULL" or threshold is to be set only loud enough to hear. In the field you want to set it in VLF Disc. and semi auto tuning.
Once you learn this detector it will amaze you with what it can do. This was my main detector for 25 years. It was as good as it got for many years. I retired it when I got my MXT in 2011.