If you're planning AM linear service from an amp, be prepared for 1) very low efficiency in the amp and 2) a 'scope will be necessary for tune-up. Tune-up is like no other mode except for screen-modulated AM. Not simply a matter of dipping the plate or peaking the output power. Just a for instance...I ran a 4-1000A in linear AM service. When tuned for 375 watts output, I was dissapating all of the tube's rating (1 KW) and then some. (Nice red color!) Found that that tube is darned rugged - it took it! (For how long, who knonws?).