Kenwood TH-77A Service Manual page 19

0211
TH-77A/E
Device Functions
Function
Mixer input selection switch
D212
Sub-UHF power line reverse-current prevention
D213
Receiver block high-input protection
D214
VCO output selection switch
360 input selection switch
VCO output selection switch
VHF PLL circuit
VHF FM IF system circuit
VHF RF power amplifier module
UHF PLL circuit
Daughter
Reference No.
Description
UHF FM IF system circuit
1 Unit (X58-3770-00)
Function
APC constant-current source
UHF mid-power setting voltage switch Jumpers VR1.
Jumpers R11 and VR1.
Turned on using 5TV and 5TU signals.
UHF low-power setting voltage switch
APC error amplifier power switch
Band selection switch (UHF) Turns the setting voltage on or off with a variable resistor.
Band selection switch (VHF) Turns the setting voltage on or off with a variable resistor.
Q?
VHF mid-power setting voltage switch Jumpers VR3.
Q VHF low-power setting voltage switch Jumpers R19 and VR3.
Q201
Q202
Sub-UHF RF amplifier
Sub-UHF mixer
; a
D High/Middle/Low selection
5TV/STU reverse-current prevention
UHF APC ATT pin diode
Amplifier high-input signal protection
Daughter
UHF noise detection
UHF power amplifier module
APC error amplifier
2 Unit (X59-3810-00)
Description
Reference No. Function
Qi 800 RF amplifier
Q2
Local oscillator doubler
Mixer
AGC level shift
Air band AF amplifier
FM discrete short-circuit
AM receiver circuit
19