Block diagram BA1404
Pin description
| Pin no. | Pin Name | Description |
| 1 | R-ch audio input | Connects to the pre-emphasis circuit |
| 2 | Input amplifier bypass | Connects to the bypass capacitor |
| 3 | GND | Low frequencies |
| 4 | 38 kHz oscillator bypass | Connects to bypass capacitor |
| 5 | 38 kHz oscillator | Connects to 38 kHz crystal oscillator |
| 6 | 38 kHz OSC | Connects to load capacitor of crystal oscillator |
| 7 | RF output | Connects to LC resonator |
| 8 | GND | High frequency |
| 9 | RF oscillator | Connects to bypass capacitor |
| 10 | RF oscillator | Connects to capacitor and LC resonator |
| 11 | Voltage Supply | Connects to variable capacitor |
| 12 | Modulation signal input | Connects to bypass capacitor and modulated signal source |
| 13 | Pilot signal output | Connects to RC mixer circuit |
| 14 | Multiplexer signal output | Connects RC mixer circuit |
| 15 | Vcc | Power supply |
| 16 | Multiplexer modulator balance | Connects to trimpot resistor |
| 17 | Multiplexer modulator balance | Connects to trimpot resistor |
| 18 | L-ch audio input | Connects to pre-emphasis circuit |