I have aquired one of these from trademe.
It is a great machine, seems identical in circuitry to my QP-3201
which is this one…
My modification is to the lower part of the wand near the coil where the metal wand connects to the coil pivot. I have inserted a piece of plastic pipe so that the metal wand now stops about 100mm short of the coil, on both my old and mew machines. This increases the two machines sensitivity in a most gratifying way.
The MD-3005 is much easier to use than the old machine as it has a proper handle and armrest and is lighter too. They are not computerised dectors and make a constant tone in the headphones which increases for non ferrous targets and decreases for ferrous ones. They have a ground ballance pushbutton.
I have 2 more conventional machines as well, a GC-1038 and a LCD display one (manufact number i cant remember but currently sold on trademe as a Barska BE11642) which are both what i would call silent runners, that is they are silent until they beep when they detect something. I prefer using the more primitive circuitry of the cheaper machines as it provides a more involved experience which makes you aware of magnetic (quieter) and conductive (louder and tonally different) responses and of ground magnetic mineralisation.