Icom IC-730 Instruction Manual page 24

13.2MHz ~ 13.9MHz signal with 1KHz steps, and sent to the
PREMIX unit.
The local oscillator is a VXO, and its frequency is varied few
KHz by the RIT control and the FREQUENCY SET control
for calibration.
6 - 10 PREMIX UNIT
The 13.2MHz ~ 13.9MHz signal from the PLL unit, is fed to
a mixer with a local oscillator frequency which is selected by
the BAND switch, and the mixer puts out the respective 1
local oscillator frequency. This output signal is fed to the
BPF unit to suppress spurious signals.
The local oscillator frequency (X) can be calculated as
follows:
X (MHz) = 39.7315MHz + (low edge frequency of the
band) MHz - 13.2MHz
This unit has a diode matrix circuit which convert the band
signal into the control signals for the CPU.
6 - 11 BPF UNIT
Consists of a band-pass filter for each band and buffer
amplifier.
st
The 1 local oscillator signal from the PREMIX unit, is
applied suitable band-pass filter which is selected by the
BAND switch.
st
The filtered signal is amplified and sent to the 1
the RF unit.
6 - 12 REG UNIT
Composed of a voltage regulator IC and a current booster
transistor. These provide regulated 8V for receive, for
transmit and for common circuits.
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st
mixer in