This general purpose signal source serves very well in signal-tracing applications. The output level is variable to more than 1 Vrms into a 50 O load. Almost any crystal in the 1 to 15 MHz range can be used. Ql forms a Colpitis oscillator with the output taken from the emitter. A capacitive voltage divider (across the 2.2 emitter resistor) reduces the voltage applied to the buffer amplifier, Q2.
The buffer and emitter follower, provides the low input impedance necessary to drive 50 O loads.