Complex sentence: By the 1930s, advances in vacuum tube manufacturing (the tetrode and, soon after, the pentode, both reducing the control grid to plate (Miller) capacitance) finally made Edwin Armstrong's Superheterodyne design practical for domestic receivers.
Split into simpler sentences: By the 1930s, advances in vacuum tube manufacturing had yielded the tetrode and, soon after, the pentode, both reduced the control grid to plate (Miller) capacitance. These advances finally made Edwin Armstrong's Superheterodyne design practical for domestic receivers.