KOA has extended the WK73 series by several sizes. For the WK73R (resistance ≥ 10 Ohm), three sizes are added, namely 0508, 0306 and 0204. The WK73S (resistance <10 Ohm) has been extended by size 0508. For size 0508 the rated power is spezified up to 1 Watt, for 0306 to 0.5 Watt and for 0204 to 0.33 Watt. The TCR is indicated with max. 100 ppm/K, the temperature range is given as -55 to +155ᵒC, the derating starts at 105ᵒC (terminal temperature). The series complies with the requirements of AEC-Q200.
Overall, the WK73R series now has 7 sizes available, from 0204 to 1225. There are 5 sizes in the low-ohm version WK73S, from 0508 to 1225. The resistance values range from 10 mOhm to 9.76 Ohm (WK73S) and from 10 Ohm to 1 MOhm (WK73R). Using the Terminal Temperature concept, nominal powers of 3 watts (1225), 2 watts (1020) and 1.5 watts (0612) are possible. All sizes are tested according to AEC-Q200. The complete series also exists in a special anti-sulfur version, designated as WK73-RT.
