3-9
1ST RX/TX LO CIRCUIT
The 41.344 MHz reference signal from the crystal oscillator
(X2001) is amplifi ed by the buffer (Q2001 and Q2002), and
then applied to the frequency multiplying circuit (Q2101),
which extracts the 3rd harmonic component, resulting in the
124.032 MHz signal.
The 124.032 MHz signal is passed through two HPFs (L2103,
C2105, C2106 and C2108), splitter (L2104, L2105, C2110
and C2111), 4 dB attenuator (R2151 to R2153) and LPF
(L2152, C2151 to C2153), and then applied to the frequency
multiplying circuit (Q2151), which extracts the 3rd harmonic
component, resulting in the 372.096 MHz reference clock sig-
nal.
The clock signal is amplifi ed by the clock AMP (Q2152), and
passed through the 2 dB attenuator (R2164 to R2166) and
SAW fi lter (FI2151), and then applied to the DDS (IC2202).
Using the 372.096 MHz reference clock signal, the DDS
(IC2202) directly generates the 38.62 to 77.24 MHz 1st TX/
RX LO signal.
The 1st TX/RX LO signal is passed through the LPF (L2241,
L2242, C2241 to C2243) and 6 dB attenuator (R2262 to
R2264), and then applied to the LO AMP (IC2203).
When the operating frequency is 400 to 470 MHz, the 1st TX/
RX LO signal is passed through the BPF (L2251 to L2253,
C2252 to C2254), instead of the 6 dB attenuator (R2262 to
R2264).
The amplifi ed signal is passed through the LPF (L2208,
L2210, C2228, C2231 and C2233), and applied to the fre-
quency multiplying circuit (D2202 and L2211), which ex-
tracts the 2nd harmonic component, resulting in the 77.24 to
162.24 MHz signal. The 1st TX/RX LO signal is then passed
through either BPF.
When the operating frequency is 30 to 107.999 MHz, the
1st TX/RX LO signal is fi ltered by the BPF (L2322 to L2327,
C2321 to C2334).
When the operating frequency is 0.03 to 29.999 MHz and 108
to 470 MHz , the 1st TX/RX LO signal is fi ltered by the BPF
(L2303 to L2308, C2302 to C2314).
The fi ltered signal is passed through the 6 dB attenuator
(R2324 to R2326), and then applied to the LO AMP
(IC2351).
The amplifi ed signal is passed through the LPF (L2352,
C2354 and C2355), and then applied to the frequency multi-
plying circuit or LPF.
When the operating frequency is 30 to 470 MHz, the 1st TX/
RX LO signal is passed through the BPF (L2402, L2403,
C2405 to C2411), and applied to the frequency multiplying
circuit (D2403 and L2404), which extracts the 2nd harmonic
component, resulting in the 154.487 to 324.487 MHz signal.
The 1st TX/RX LO signal is passed through the HPF (L2407,
C2416, C2418 and C2419).
When the operating frequency is 29.999 MHz and below,
the 1st TX/RX LO signal is passed through the LPF (L2405,
C2414, C2415 and C2417).
The fi ltered signal is passed through the 6 dB attenuator
(R2414 to R2416), and applied to the LO AMP (IC2401). The
amplifi ed signal is passed through the 360 MHz LPF (L2414,
and C2429 and C2430), 120 MHz HPF (L2412, C2425 and
C2426) and one on the BPFs, depending on the frequency,
to remove unwanted signals. (See the 1ST LO BPF TABLE
below.)
When the operating frequency is 30 to 470 MHz, the 1st TX/
RX LO signal is passed through the LPF (L2754, C27532
and C2755) and applied to the frequency multiplying circuit
(D2752 and L2756), which extracts the 2nd harmonic com-
ponent, resulting in the to 594.487 MHz signal.
The fi ltered 1st LO signal is amplifi ed by the LO AMP
(IC2801), and passed through the HPF (L2802, C2805 and
C2806), and then applied to the 1st IF mixer.
• While receiving on the HF band
The 1st LO signal is applied to the 1st IF mixer (Q3231 and
Q3232).
• While operating on the VHF/UHF band
or transmitting on the HF band
The 1st LO signal is applied to the 1st IF mixer (D3252 and
D3253), through the LPF (L3256, C3244 to C3246) and 3 dB
attenuator (R3254 to R3256).
Reference
frequency
41.344 MHz
X3
124.032 MHz
X2001(TCXO)
Q2101
Q2151
IC2202
IC2002
IC2003
D2202, L2211
D2403,
L2404
D2752,
L2756
1/4
X3
372.096 MHz
HF: 62.24 to 77.24 MHz
VHF: 38.62 to 81.12 MHz
UHF: 65.56 to 74.31 MHz
HF: 124.517 to 154.487 MHz
VHF: 77.24 to 162.24 MHz
UHF: 131.12 to 148.62 MHz
X2
X2
X2
1st LO DDS
HF 1st LO frequency:
142.517 to 154.487 MHz
Operating frequency:
0.03 to 29.999 MHz
Operating frequency:
30 to 199.999 MHz
Operating frequency:
400 to 470 MHz
VHF 1st LO frequency:
154.487 to 324.487 MHz
UHF 1st LO frequency:
524.487 to 594.487 MHz
2nd LO:
124.032 MHz
3rd LO:
419 kHz
3rd LO DDS
10.336 MHz
• FREQUENCY CONFIGURATION DIAGRAM
• 1ST LO BPF TABLE
Filter
Operating fre-
quency
(MHz)
Filter
switches
Components
Control line
(Active
High)
BLF1
0.03 to
29.999999
D2501
D2502
L2502 to
L2506, C2501
to 2511
BLF1
BLF2
30.0 to
59.999999
D2551
D2552
L2552 to
L2557, C2551
to C2565
BLF2
BLF3
60.0 to
115.512999
D2601
D2602
L2602 to
L2607, C2601
to C2613,
C2615
BLF3
BLF4
115.513 to 148.0
D2651
D2652
L2652 to
L2657, C2652
to C2665
BLF4
BLF5
148.000001 to
199.999999
D2701
D2702
L2702 to
L2707, C2701
to C2714
BLF5
BLF6
400.000000 to
470.000000
D2751
D2753
L2755, L2757
to L2759,
L2761
BLF6
