Theory Of Operation: Major Assemblies 2-9
2.2.7 Power Supply
There are 4 voltage supplies in this radio: SWB+, 3.3 V, 5 V and 10 V.
SWB+ voltage is distributed to SW/Vol 1, Final PA (Q403 via R417) and APC circuit (U401).
The 3.3 V regulated supply (U506) is applied to CPU (U101), EEPROM (U104), DTMF IC (U103),
Audio processor IC (U102), microphone biasing circuit and LCD/keypad driver.
The 5.0 V regulated source (U505) is distributed to RX back end circuit, RX/TX audio filters,
1/2 VCC generator, VCO (Q705 and Q706), RX B+ (Q304), TXvB (Q407) and VCTCXO.
The 10.0 V regulated source (U507) is solely applied for Charge pump use.
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