actually my quuestion was: Is it possible (by usting shielded cabling) to house the BU card in the joystick and connect the throtthe to it with a multi stranded cable (as the oldd school controllers) or i have to buy a card for each piece?
Yes, I usually re-use old gameport cables and your DB15 connector - since they have many internal wires (up to 15) and local market don offer similar one - for throttle button matrix.
For (throttle) axis I use shield cable when possible.
Note: In F16FLCS+TQS is possible hook throttle (TQS) into joystick base using just one original gameport cable.
For Suncon SFS you need two cables since they have more buttons (originally 19 buttons + 2 axis), unless find cable with ~20 internal wires.
If yes can use (just as example) a 2 meter cable between the throttle controls and the BU housed in the joystick base?
Considerations: Actually Windows recognize up to 8 axis, 32 buttons and (1) HAT.
Using one USB controller inside each (joystick, throttle..) you overcome this limit (G940 Warthog approach), and can use additional axis for rudder pedal, trim wheels, buttons for additional panels...
CON - Old games(1) don't recognize more than one USB controller, so if you still playing Red Baron...
(1)COTS HOTAS overcome this with programing software.