The basic design of the HKS drift chamber (HDC1 and HDC2) is similar to the well established Jlab standard drift chambers used for the SOS spectrometer. The two chambers are identical and its effective area of the HDC is with xx' uu' vv' wire layers (figure 19). Anode wires (30 m gold-plated tungsten) are strung with a separation of 1 cm on each layer plate made of glass epoxy (figure 20). Layers are assembled with O-rings and cathode aluminum foils are inserted between layers. Signals from the anode wires are amplified and discriminated with the Nanometrics N277L boards mounted on the chamber frame(see section 9).