Icom IC-7800 Service Manual Addendum page 367

3-7-22 BUFFER IC (MAIN UNIT; IC251)
Pin Port
number name
Outputs the bandpass filter (B7)
selecting signal during transmit.
11 TXB7
High : While
Outputs the bandpass filter (B6)
selecting signal during transmit.
12 TXB6
High : While
Outputs the bandpass filter (B5)
selecting signal during transmit.
13 TXB5
High : While
Outputs the bandpass filter (B4)
selecting signal during transmit.
14 TXB4
High : While
Outputs the bandpass filter (B3)
selecting signal during transmit.
15 TXB3
High : While
Outputs the bandpass filter (B2)
selecting signal during transmit.
16 TXB2
High : While
Outputs the bandpass filter (B1)
selecting signal during transmit.
17 TXB1
High : While
Outputs the bandpass filter (B0)
selecting signal during transmit.
18 TXB0
High : While
3-7-23 BUFFER IC (MAIN UNIT; IC261)
Pin Port
number name
Outputs the transmit output power
control signal.
12 AMS
High : Transmitting in AM mode.
Outputs the transmit output power
control signal.
13 50MS
High : Transmitting in 50 MHz band.
Outputs the HF band transmitting
14 HFS
power control signal.
Outputs the bandpass filter (B10)
selecting signal.
16 TXB10
High : While
Outputs the bandpass filter (B9)
selecting signal.
17 TXB9
High : While
Outputs the bandpass filter (B8)
selecting signal.
18 TXB8
High : While
Description
transmitting
11–15 MHz.
transmitting
8–11 MHz.
transmitting
6–8 MHz.
transmitting
4–6 MHz.
transmitting
3–4 MHz.
transmitting
2–3 MHz.
transmitting
1.6–2 MHz.
transmitting
0.03–1.6 MHz.
Description
transmitting
30–60 MHz.
transmitting
22–30 MHz.
transmitting
15–22 MHz.
3-7-24 SERIAL/PARAMETER IC
(RXPLL-A UNIT; IC1)
Pin Port
number name
on 4 PST2A
5 PST1A
on
6 PST3A
7 PST4A
on
3-7-25 SERIAL/PARAMETER IC
(RXPLL-B UNIT; IC1)
on
Pin Port
number name
4 PST2B
on
5 PST1B
on
6 PST3B
7 PST4B
on
3-7-26 DDS IC (RXPLL-A UNIT; IC101)
Pin Port
on
number name
67 MUTA
68 VA6S
70 VA5S
71 VA4S
73 VA3S
74 VA2S
on
75 VA1S
on
on
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Description
Outputs the strobe signals to the 1st
LO PLL IC on the RXPLL-A unit.
Outputs the strobe signals to the 1st
LO DDS IC on the RXPLL-A unit.
Outputs the strobe signals to the 2nd
LO DDS IC on the RXPLL-A unit.
Outputs the strobe signals to the T3
LO DDS IC on the RXPLL-A unit.
Description
Outputs the strobe signals to the 1st
LO PLL IC on the RXPLL-B unit.
Outputs the strobe signals to the 1st
LO DDS IC on the RXPLL-B unit.
Outputs the strobe signals to the 2nd
LO DDS IC on the RXPLL-B unit.
Outputs the strobe signals to the T3
LO DDS IC on the RXPLL-B unit.
Description
Outputs the 1st LO muting signal to
the RXPLL-A unit.
High : While muting.
Outputs the 1st LO VCO (VCO6) con-
trol signal to the RXPLL-A unit.
High : While receiving on 45–60 MHz.
Outputs the 1st LO VCO (VCO5) con-
trol signal to the RXPLL-A unit.
High : While receiving on 30–45 MHz.
Outputs the 1st LO VCO (VCO4) con-
trol signal to the RXPLL-A unit.
High : While receiving on 22–30 MHz.
Outputs the 1st LO VCO (VCO3) con-
trol signal to the RXPLL-A unit.
High : While receiving on 15–22 MHz.
Outputs the 1st LO VCO (VCO2) con-
trol signal to the RXPLL-A unit.
High : While receiving on 8–15 MHz.
Outputs the 1st LO VCO (VCO1) con-
trol signal to the RXPLL-A unit.
High : While receiving on 0.03–8 MHz.