TW-42 ultra-short wave radio transmitter high frequency power amplifier circuit part

It is a high-frequency power amplifier circuit for ultra-short wave radio transmitter. This circuit uses the high-frequency integrated power discharge
circuit M57704H from Mitsubishi Corporation of Japan.
    The radio station uses frequency modulation, the operating frequency is 457-458MHz, and the transmitting power is 5w. As can be seen from the figure, after the input constant amplitude FM signal
is amplified by M57704H, one path is matched and filtered by the microstrip line, and then sent to the multi-section LC network through VT1, and then transmitted
out by the antenna; the other path is detected by VD2 and VD3 ． After VT2 and VT3 are DC amplified, they are sent to the VT1 adjustment tube, which is
used as a control voltage from the second pin of M57704H to adjust the collector power supply of the first-stage power amplifier, which can stabilize the output power of the entire integrated power amplifier. The collector power supply of the second and third stage power amplifiers
is fixed at 13.8V.