... input directly, microstrip combiner. ZHC618F-3KW FM TransmitterInnovative digital fm stereo transmitter for professional radio stationInput audio: Analog and digital (AES ... : 0.05dB, 10Hz~15000MHz14. Distortion: 0.1%, 30 Hz ~15KHz15. Stereo FM transmitter Separation: 55dB, 30Hz~15KHz16. Pilot frequency: 19kHz