1St Tx If Circuit (Main Unit); 1St Tx If Circuit - Icom IC-7100 Service Manual

1ST TX IF CIRCUIT (MAIN UNIT)

The 1st TX IF signal from the 2nd TX IF circuit is applied to
the 1st TX mixer (D3252 and D3253), then mixed with the 1st
TX LO signal, resulting in a signal at the TX frequency.
The converted TX signal is applied to the TX amplifi er circuit.
• While operating on the HF, 50 MHz and 70 MHz bands -
The TX signal is passed through the LPF (L3261 to L3263,
C3216 to C3267) and one of the BPFs, depending on the
operating frequency, to remove unwanted signals.
The fi ltered signal is applied to the TX power amplifi er cir-
cuit.

• 1st TX IF CIRCUIT

1st MIXER VUHF/HFTX
D3252,D3253
From the 2nd TX IF circuit
1LO
HF/VHF: 124.517-324.487MHz
UHF: 524.487-594.487MHz
D3272
f c=500MHz
430-450MHz
LPF BRF
VHF/UHF BAND ->
144-148MHz
fc=74.8MHz
LPF
MAIN UNIT
• While operating on the 144 MHz and 430 MHz bands -
The TX signal is passed through the LPF (L3261 to L3263,
C3216 to C3267) and BRF (D3272, L3271, L3272, C3271 to
C3273).
• 144 MHz band signal
The TX signal is passed through the 3 dB attenuator (R3035
to R3037) and 146 MHz BPF (MAIN UNIT: L3032 to L3035,
C3036 to C3046), and then amplifi ed by the RF AMP
(IC3031).
The amplifi ed signal is applied to the TX power amplifi er cir-
cuit.
• 430 MHz band signal
The TX signal is passed through the 3.5 dB attenuator (R3052
to R3054), and amplifi ed by the RF AMP (IC3051). The am-
plifi ed TX signal is sequentially passed through the BPF
(FI3052), LPF (L3052, C3053, C3054) and BPF (FI3051).
The fi ltered signal is applied to the TX power amplifi er cir-
cuit.
IC3051 FI3052
3.5dB
RF
ATT BP F
AMP
BW=20MHz
6dB f0=146MHz
ATT BP F
BW=10MHz
0.03-1.6MHz
LP F
1.6-2.0MHz
2.0-3.4MHz
HP F
3.4-6.9MHz
HP F
6.9-13.9MHz
HP F
13.9-20.9MHz
HP F
20.9-40.0MHz
HP F
40.0-60.0MHz
BPF
60.0-74.8MHz
HP F
3-6
FI3051
fc=500MHz
To the band filter circuit
LP F BPF
BW=20MHz
IC3031
RF
AMP
1.6-74.8MHz
HPF