OK - I finally found a micro-usb 3 to USB adapter with the correct pin grounded (connection between ground and adjacent 'I/O' pin, NOT the center pin)
With this usb pin connection, the TAB 8 reads memory sticks on the usb port without system setting adjustments. It just recognizes the connecting - flags a notice to the user and opens the drive when the notice is tapped (maybe tapped a few times - hard to tell with this screen).
All the other micro-usb hardware I had was missing this connection. I asked Mohamed at the cell phone shop next door to keep an eye out for one. His supplier had just that - one adapter. Now it's mine. Nobody else can have it.
I actually went through a couple of places checking to see if ANY of their micro-usb connectors or peripherals had this connection. (have socket with pin sensors attached) NADA.
So when someone says it's USB OTG, measure it.
Might be worth kludging the contact permanently if ever the TAB 8 is in the shop for battery, screen or other repairs.
RL