A JFET (Ql) serves as the oscillator. D2 helps to stabilize the transistor by limiting positive sinewave peaks and stabilizing the bias. Output from Ql is supplied to a class A buffer, Q2. It operates as a broadband amplifier by means of Tl, which is untuned. Output amplifier Q3 is also a class A stage. A low-pass, single-section filter is used at the output of Q3 to remove some of the harmonic currents generated within the system.
The filter output impedance is 50 ohms. The injection level to the mixer is 600 mV p-p.