Receiver Circuit; Transmitter Modulation Circuit; Transmitter Amplifier Circuit - Ranger RCI-6900F HP Manual

Q25, Q27, Q28, Q29 and Q61. The PLL circuit is programmed by the rotary channel switch GPS-0501.
The GPS-0501 communicates the correct binary data information to the programmable divider inside
of IC3. IC3 then controls the VCO (Voltage Controlled Oscillator), to oscillate on the correct
frequency. This signal is fed either into the receiver's first mixer (for receive operation) or the
transmitter's mixer (for transmit operation).

3.2 RECEIVER CIRCUIT

The incoming RF signal comes into the radio via the antenna and into the front-end pre-amp, Q17. The
RF signal is fed into the mixer circuit of the Q18 & Q19 and then into the AM IF section of the
receiver (depending on the mode of operation). The signal is then detected by either the AM detector or
product detector or then fed to the audio amplifier section of the receiver and finally out to the speaker.

3.3 TRANSMITTER MODULATION CIRCUIT

(i) The transmitter modulation circuit modulates the low-level RF signal from the PLL exciter circuit
with the user's audio voice signal from the microphone. The audio from the microphone is then
amplified and fed into the transmit amplifier circuit.
(ii) If the transceiver is in the AM mode, the AF Power amplifier modulates the last RF amplifier,
which produces a true amplitude modulated RF signal.

3.4 TRANSMITTER AMPLIFIER CIRCUIT

The transmitter takes the basic exciter signal from the TX mixer and amplifies it through a series of
amplifiers consisting of Q50, Q51, Q49, Q47, Q48 and EPA010010B (only for RCI-6900F TB) where
it is sent out to the antenna connector.
- 9 -