Logic Circuits - Icom IC-706 Service Manual

While transmitting in FM or FM narrow mode, the BFO
circuit generates a 9.0115 MHz or 9.0100 MHz frequency
as the TX FM PLL reference frequency, respectively.
Mode
RX BFO/3rd LO TX BFO/FM PLL ref.
frequency [MHz] frequency [MHz]
USB 9.0130 9.0130
LSB 9.0100 9.0100
CW
9.0106 9.0106
( - CW pitch frequency) ( - CW pitch frequency)
CW-R
9.0106 9.0106
(+
CW pitch frequency)
(+
CW pitch frequency)
RTTY
9.008375
(2125 Hz
tone)
9.0105 (MARK)
9.008885
(1615 Hz
tone)
AM
No output 9.0100
FM
9.4665 (3rd LO) 9.0115 (PLL ref.)
FM nar.
9.4650 (3rd LO) 9.0100 (PLL ref.)
WFM
No output No output
IF shift: Center RTfY: Normal polarity
3·4 LOGIC CIRCUITS
3-4-1 BAND SELECTION DATA
(MAIN AND PLL UNITS)
To select the correct RFlow-pass filter, high-pass filter and
VCOs on the PLL unit, the CPU outputs the following band
selection data from the I/O expander (MAIN unit IC31,
IC32), the
NO
converter (MAIN unit IC35) or DDS IC (PLL
unit ICl 0) depending on the displayed frequency.
The
NO
converter output from IC35 pin 5 is doubled by 2 at
IC34a to obtain the band voltage for external equipment.
Band selection data
IC31,IC32 IC35
ICl0 (PLL)
Frequency
(MAIN) (MAIN)
(MHz)
HPF
LPF
1/2 band
VCO
LPF
BPF
. voltage
BPF
0.03-1.999
Ll L1 3.76 V
2.0-3.999
L2 L2 3.08 V
4.0-7.999 L3 L3 2.57 V
8.0-10.999 OV VCOl LOFl
L4 L4
11.0-14.999 2.06 V
15.0-21 .999 L5 L5 1.61 V
22.0-29.999 L6 L6 1.12V
30.0-39.999 B7W
L7 VC02 LOF2
40.0-59.999 B7
60.0-128.999 VC01 LOF3
B8W
0.61 V
129.0-143.999 LOF4
144.0-148.000 B8
L8
LOF5
VC02
148.000001-
BSW
LOF4
200.000000
3-8
3-4-2 MAIN CPU PORT ALLOCATIONS
(MAIN UNIT IC25)
Pin Port
Description
number name
9
SPS
Outputs a mute signal for AF power
(P52) amplifier according to the [PHONES]
jack.
13 DASH Input port for DASH signal of the
(P97) paddle to the internal keyer.
14 DOT Input port for DOT signal of the
(P96)
paddle to the internal keyer.
15 SNDL
Input port for transmit/receive
(P95) switching signals. This port becomes
"High" while transmitting.
16 TKEY Input port for the keying signal of
(P94) optional AT-180/AH-3 antenna tuners.
17 TCON Input port for the optional AH-3
(P93) antenna tuner.
19 PWK Input port for the [POWER] switch.
(P91)
20 POWS Outputs a power ON signal.
(P90)
21 ATST
Outputs start signal for the optional
(P60) AT-180 antenna tuner.
22
BEEP Outputs beep tone and CW side tone
(P61) signals.
23 AHST
Outputs start signal for the optional
(P62) AH-3 antenna tuner.
24
sass
Outputs a squelch control signal.
(P63)
30
SMV S-meter level input for squelch
(P70) control.
31 NSaV FM noise level input for squelch
(P71)
control.
32 FORV Forward RF power level input for Po
(P72) and SWR meter indications.
33 REFV Reflected RF power level input for
(P73) SWR meter indication.
34 ALCV ALC level input for ALC meter
(P74) indication.
37
TONE Outputs subaudible tone signals.
(P77)
39 BUSY Input port for the optional UT-1 02
(P40) busy signal. This port becomes
"High" during speech synthesis.
40 ETON Outputs tone burst signals for
(P40) European repeaters.
41 SPST Outputs a strobe signal for the
(P42)
optional UT-102.
42 lOT Outputs serial data for the I/O
(P43) expanders, optional AT-180/UT-102.
43 ICK Outputs a clock signal for the I/O
(P44)
expanders, optional AT -1801UT -1 02.