Service Manual Part 1

  8+
  
8+ $3)6
The l0.7MHz signal from the RF PCB feeds Q104, passes through a crystal filter (Xl0l)
and is amplified by Q111 and Q112 before passing through a 10.7MHz ceramic filter to a
mixer/oscillator (Qll3). This 455kHz mixer output is further filtered and amplified by
CF102, CF103 and Q114, then passes back to the RF PCB where it is demodulated by
IC101. The RSSI function is internal to IC101.
The demodulated signal is filtered and compensated on the IF PCB before passing to the
logic PCB via the RF PCB. Narrow band or wide band response is determined solely by
the IF PCB.
      
The processed transmit audio passes to the RF PCB where it is split into a VCO modula-
tion path and a TCXO modulation path. The TCXO path passes through a potentiome-
ter to enable the dual point modulation to be correctly adjusted, and then returns to the
TCXO/Tx audio PCB.