Pll Circuits; Power Supply Circuits; Voltage Lines; Vco Circuit - Icom IC-F1010 Service Manual

4.3 PLL CIRCUITS
4.$1 PLL CIRCUIT
A PLL circuit provides stable oscillation of the transmit
frequency and the receive 1st LO frequency. The PLL circuit
consists of the PLL lC (1C12), charge pump and loop filter and
employs a pulse swallow counter.
Signals from the VCO through butfer amplifiers (Q19, Q1 8) are
prescaled in the PLL lC (1C12) based on the divided-ratio (N-
data). The PLL lC detects the out-of-step phase using the
reference frequency and outputs it from pin 6. The output
signalis passedthrough thecharge pump (Q3GQ33) and loop
filters (R154/C181 , R153/C179), and is then applied to the
VCO circuit as the lock voltage.
The accelerator switch (lC13a/b) selects the effective loop
filter to accelerate the lock up speed.
The lock voltage is also used for the receiver tunable bandpass
filters to match the filter's center frequency to the desired
receive frequency. The lock voltage is amplified at the buffer
amplifier (Q29) and is then applied to the bandpass filters
(D8-D11).
4-3-2 VCO ClRCUlr
The VGO circuit contains a separate Rx VCO (Q21 , D19, D20,
D40, D41) and Tx VCO (Q23, D21,D22, D42, D43). The
oscillated signal is amplified at the buffer amplifiers (Q19, Q20)
and is then applied to the Tx/Rx s'lvitching circuit (D17, D1 8).
Then the Rx signal is applied to the 1st mixer (Q2) via the
amplifier (Q3) and the Tx signal to the driver (Q17).
A portion of the signal from Q19 is amplified at the buffer
amplifier (Q1 8) and is then fed back to the PLL lC (1G12 pin 1 1 )
as the comparison signal.
. PLL GIRGUIT BLOCK DIAGRAM
4.4 POWER SUPPLY CIRCUITS
4.4.1 VOLTAGE LINES
Rx VCO
Q21, D19, D20, D40, D41
To
Tx/Rx switch
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LINE DESCRIPTION
HV
The voltage from the extemal power connector.
vcc
The same voltage as the HV line which is controlled by
nPWONn signal from the CPU (1C20 pin 67) using a
switching FET (O12).
CPU5V Common 5 V converted from the HV line at the 5 V
regulator lC (1C17). This voltage is supplied to the GPU
regardless ol the power switch.
+5V Common 5 V converted from the VCC line at Q42, Q43
and D30 using the GPUSV line as the reference voltage.
{8V Common 8 V converted from the VCC line at 1C16.
R8V Receive 8 V controlled by "VRX" signal from the CPU
(1C20 pin 66). This voltage is converted from the VCG
line at Q36 andD27 using the +8V line as the reference
voltage.
T8V Transmit 8 V controlled by "VTX" signal from the CPU
(1C20 pin 65). This voltage is converted from the VCG
line at Q40 and D29 using the +8V line as the relerence
voltage.
MTSV Transmit 8 V controlled by 'TMUT'signal lrom the CPU
(1C20 pin 60). This voltage is converted from the VCC
line at Q38 and D28 using the +€V line as the reference
voltage.
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