Kenwood TK-90 Service Manual page 39

COMPONENTS DESCRIPTION /
Ref. No. Use / Function
D252 Switching 1/2: ON when AM mode is selected
2/2: ON when 2.4kHz SSB filter is
D253 Switching ON when option filter is selected
D254 Switching ON when AM mode is selected
D255 Switching ON when AM mode is selected
IF path transmission/reception
changeover
D256 Switching ON when SSB mode is selected
IF path transmission/reception
changeover
D257 Switching ON when option filter is selected
IF path transmission/reception
changeover
D258 Switching ON when option filter is selected
D259 Switching ON during transmission
D260 Reverse current AM mixer balance
prevention
D261 Temperature AM mixer balance
compensation
D321 Rectification NB voltage generation
D361 5.1V zener diode Over input protection
D362 5.6V zener diode Voltage shift
D363 Reverse current Over input protection
prevention
D364 5.6V zener diode Over input protection
D365~369 Reverse current Reverse current prevention
prevention
D370 3.9V Zener diode Voltage shift
D371,372 Reverse current Reverse current prevention
prevention
D373 Temperature Temperature compensation
compensation
D374 Reverse current Reverse current prevention
prevention
D451 Reverse current RBK signal
prevention
D452 PIN diode IF gain control
D453 Rectification AGC control voltage generation
D454 Rectification AM detection
D521,522 Reverse current Time constant
prevention
Operation / Condition
selected
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