544
The Type 544 is a 50MHz scope with tunnel diode triggering. It has only one timebase. A factory modification, MOD 108G, was available that increased the accelerating voltage to 24kv. The 1968 catalog lists an RM544 Mod 720 which has a direct-access plug-in and has 1ns risetime.
The vertical amplifier of the 544 is the same as the vertical amplifier of the 546 and 547.