Hi everyone....
I replaced both of the ZTX109 Transistors on my 1981 RD112-100.
I used a BC237B transistor..seemed like a good match and is working OK. Supposely the BC237B is a low-noise transistor for audio pre-aplification
Description:
BIPOLAR TRANSISTOR, NPN, 45V, TO-92
Transistor Polarity: NPN;
Collector Emitter Voltage V(br)ceo: 45V
Transition Frequency: 200MHz
Power Dissipation 350mW
DC Collector Current:100mA
DC Current Gain: 290 hFE
General purpose NPN silicon planar epitaxial transistors, best suited for use in driver
stages of audio amplifiers, low noise input stages of tape recorders. Hi-Fi amplifiers,
signal processing circuits of television receivers