Operating instructions

DMH Series VHF Radio General Information
BK RADIO Page 4-3
(3) Loop Filter – Smoothes the output of the Synthesizer IC to reduce undesired
modulation of the VCO frequency.
(4) VCO Coarse Tune Filter – When changing to a new frequency that requires a
different Coarse Tune voltage, a switch is closed for a short time to allow the VCO
control voltage to change to the new value rapidly. Otherwise the VCO Coarse Tune
Filter provides a low noise voltage for setting the range of the VCO frequency.
C. Voltage Regulators
Several voltage regulators provide power for the circuitry located on the System Board.
D. Baseband Signal Processor
(1) Baseband Signal Processor - Implements filters, tone generators, and other signal
processing algorithms required for analog and digital modes of operation.
(2) TCXO – Provides a stable oscillator frequency for the Baseband Signal Processor.
4.3.2 RX BOARD
A. Buffer
Q101 provides gain to supply the mixer and transmit buffer.
B. TX Buffer
Q102 and associated circuitry provide gain to drive the PA module.
BASEBAND SIGNAL PROCESSOR
TCXO
19.6608 MHz
MIC
DISC
AUDIO
SPEAKER
AUDIO
TX AUDIO
CONTROL /
DATA BUS
TO CORE
µ P