Solid State10kW Digital Amplitude Modulation MW Radio Transmitter

• Introduction                                                 

10kW solid-state digital AM transmitter is latest developed by BBEF. It introduces advanced digital amplitude modulation and power synthesizer technology that brings excilent specifications. Audio processor is added in audio channel that effectively improves the amplitude modulation capacity; the full efficiency is better than 84%. It is the ideal machine for customers because of its simple construction, perfect measurements of control, monitor and safety.

The modulation processes as follow: First, audio input signal is converted into data address code in A/D converter. Second, in modulation coders the data from A/D converter address and produce digital signal needed in PA.  Third, digital output from modulator and coders control the on-off of the RF amplifier. These independent RF amplifiers are series-wound in a PA combiner. The RF amplifiers and combiner make up of PA. The AM output is produced through turning on different number of independent RF amplifiers. 

High frequency channel: The carrier frequency signal produced by oscillator is amplified, excited in head stage. Then it is slipped into several in-phase high frequency output and the output is sent to every high frequency PA units.

Audio channel: Through Bessel filter after the audio processor had controlled signal level automatically, audio signal is added with a DC signal. In this course, modulation level is determined by audio signal, and the power of carrier is determined by DC signal. The analog compound signals (audio and DC) can be converted into 12-bit data signals. In modulation coders, as addressing codes, these data signals are converted into signals that control the on-off of every RF PA.

Output network: Output network includes a Butterworth BPF and a “T” network, the former passes carrier frequency and attenuates harmonic, the later matches the transmitter’s load.

• Technology Specification                                 

Carrier power                         10kW

Carrier frequency                    Any appointed frequency within 531~1602kHz

Frequency stability                 1Hz per day

Output impedance                  50Ω(unbalanced)

High frequency output port    1-5/8″EIA flange

Harmonic and spurious          Meet national standard

Carrier drop                             Less than 1%(1kHz,100% mod) ; Typically less than 0.5%

Audio frequency response     Better than ±1dB(40~7000Hz, 1000Hz as reference)

Audio harmonic distortion      Less than 1%( 95% mod, 40~7000Hz)

Noise and spurious                -65dB or better (at 1kHz,100% mod)

Audio input                              -10~+10dBm,600Ωbalanced

Mains power                            380V AC, 3 phase/4lines, 50Hz

Overall efficiency                     Better than 85% at 10kW

Power consumption                Power input 11.9kVA at 10kW carrier

Ambient temperature             0~40℃(debate 2℃ per 400m)

Humidity                                   0~90%, non-condensing

Cooling                                     Forced air cooling

Size                                          2000(h)×1830(w)×760(d)mm