8611 MECHANICAL STRUCTUREOperabilityThe keys and rotary knobs, which have a direct bearing on the operability, adopt a layout that allows their direct accessand are designed for intuitive operation.The TS-890S has 72 keys and 13 rotary knobs of various sizes, adjusted to internal and external shafts diameters.The TS-990S, which is the higher-end model, has 110 keys and a total of 28 rotary knobs of various sizes, adjusted tointernal and external shafts diameters.Although there are less keys on the TS-890S compared to the TS-990S due to the difference in the size of thetransceiver set, the TS-890S adopts a greater variety of key shapes (15 types) than the TS-990S (12 types). Having awider variety of shapes allows for more intuitive operation.Meanwhile, the TS-890S inherits the well-received design of the rotary knobs on the TS-990S, which are optimallyplaced apart from one another for enhanced operability.Fig. 90 TS-890S and TS-990SWhen determining the design layout of the TS-890S, the market evaluation and issues of the TS-990S have been takeninto consideration. At the same time, to ensure the optimal layout of the keys and rotary knobs, a 3D printout of the keyand rotary knob layout was created before mock-ups (dummy models with the actual dimensions) were manufactured toreview the size, shape, position and spacing of the individual parts.The well-received layout of the TS-990S, which allows direct access to the keys and rotary knobs, is also adopted onthe TS-890S. By actually trying out the TS-890S, you will be able to have a direct feel of the positioning of the keys androtary knobs, which are divided into separate functional blocks. Yet another design concept that the TS-890S takes afterthe TS-990S is the assignment of a single function to a key or rotary knob with little complexity in the structure and aminimal number of keys or rotary knobs with multiple functions.