Original sentence: A "heterodyne" receiver had an oscillator circuit, called a local oscillator, that produced a radio signal that was adjusted to be close in frequency to the signal being received, so that when the two signals were mixed the difference or "beat" frequency was in the audible range.Heterodyning was invented by Fessenden as a technique to make the Morse code radiotelegraph (CW) signals used during the wireless telegraphy era audible.Later, the superheterodyne receiver (superhet) was invented by Edwin Howard Armstrong in 1918, converting the incoming Radio Frequency (RF) to a fixed Intermediate Frequency (IF), using the heterodyne technique.The original heterodyne technique tried to accomplish all of this in one stage thus producing an unstable amplifier.The original heterodyne technique was pioneered by Canadian inventor-engineer Reginald Fessenden in 1901, but was not pursued very far because local oscillators were not very stable at the time.This technique is still used in radio telegraphy; the oscillator is now called a beat frequency oscillator
Edited sentence: He did not pursue it very far because his local oscillator was not sufficiently stable.Heterodyning was introduced to make the Morse code CW radiotelegraph signals used during the early wireless telegraphy era audible.Later, the superheterodyne receiver (superhet) was invented by Edwin Howard Armstrong, in 1918, converting the incoming Radio Frequency (RF) to a fixed Intermediate Frequency (IF), using the heterodyne technique.The "heterodyne" receiver or "beat receptor" had an oscillator circuit, called a local oscillator, that produced a radio frequency current that was adjusted to be close in frequency to the signal being received, so that when the two signals were mixed the difference or "beat" frequency was in the audible range.The heterodyne technique was first used by Tesla around 1896 to make continuous-wave (CW) wireless transmission test signals audible.The original heterodyne technique tried to accomplish all of this in one stage, thus producing an unstable amplifier.The term was coined by Canadian inventor-engineer Reginald Fessenden, who adopted the technique in 1901.This technique is still used in radio telegraphy, the local oscillator now being called the beat frequency oscillator