The 3SK41 has been obsolete for decades. You will likely need a replacement. Based on direct electrical comparison, here are the best :
Back in the late 1970s and early 80s, amateur radio enthusiasts (hams) faced a constant battle with and "front-end overload"—where a strong nearby signal would drown out the faint, distant voices they were trying to catch. 3sk41 datasheet
When searching for a , you will often encounter suffixes: 3SK41A and 3SK41B . These are not interchangeable without design consideration. The 3SK41 has been obsolete for decades
Crucial for selecting and converting television and radio broadcast frequencies. Oscillators: 3sk41 datasheet