MIXER AND BUFFER AMPLIFIER A1400 (TRANSMIT MODE).

TM 11-5820-670-30

1-43. MIXER AND BUFFER AMPLIFIER A1400 (TRANSMIT MODE).

In transmit mode, mixer V1401 receives two signals:

Frequency modulated signals from isolation amplifier A6600.

The signal from local oscillator module A1500.

The mixer heterodynes the two signals and applies a modulated 11.5 MHz if. signal to if. attenuator

A4900 and first and second if. amplifier A8300 through buffer amp Q1401.

Buffer amp Q1401 operates only in the transmit mode. During transmission, +16 vdc is applied, for

biasing, to the buffer amp through relay K9603. The amplifier provides sufficient amplification to drive

first and second if. amplifier A8300.

The signals applied from mixer A1400 to A8300 are discussed in the master oscillator frequency

control loop in paragraph 1-34.

The mixer applies a modulated 11.5 MHz if. signal through the receiver circuits for the purpose of

allowing the radio set operator to hear what he is transmitting. This signal is applied from the mixer

through A4900 and A4100 to module A4200.

1-43