Venue 11 Pro 7140: Usage of K12A keyboard when 7140 is docked in dock station?

Hi

I only have a power adapter for the dock station, so for charging I must dock-in the 7140. But docked the K12A keyboard can bot ne attached and so I can not work. And no, I do not own an USB- or BT-keyboard nor I want to buy one. Isn't there any way to make usage of the not really cheap K12A keyboard? What kind is the electrical connection between 7140 and K12A - the 2 x 6 pins? Maybe USB or somewhat special or simple direct wird of the keyboard controller? Or does the K12A has a hidden feature for activating BT or the micro-USB also for data transfer?

Regards, Michael