3-2-5 RF CIRCUIT (MAIN, PA UNITS AND DRIVER BOARD)

The RF circuit amplifies operating (transmitting) frequency to obtain 150 W of RF output.

The signal from the 1st IF mixer is passed through one of the low-pass filter or bandpass filters (Refer to page 4-1 bandpass filters used), and then applied to the YGR amplifier (IC1, pin 1) after being passed through the attenuator (R5–R7). The amplified signal passes through the low-pass filter (L1–L3, C1–C7) and attenuator (R1–R3), and then applied to the PA unit via J1.

The signal applied from the MAIN unit is amplified at 2 amplifiers (PA unit; Q6101 and Q6801). A part of output signal from 2 amplifiers are applied to the amplifiers to improve the frequency characteristic by feedback. The amplified signal is applied to the drive amplifier (DRIVER board; Q6851) via the J6301 as “DRVI” signal. The signal from the DRIVER board passes through the impedance converter (PA unit; L6301), and then applied to push-pull amplifiers (PA unit; Q6401, Q6402) to obtain a stable 150 W of RF output power. A part of the RF output power returns to the amplifiers to obtain a stable gain between 1.6 MHz and 27.5 MHz bands by using feedback transformer (L6404). The output power is applied to the filter unit via the J6401 as “FLIN” sig- nal.

The amplified signal is applied to the one of the 8 low-pass filters which are composed chebychev type.

•1.6–1.9999 MHz signal

The signal is applied to the relay (FILTER unit; RL7031) which is controlled by the band control IC (MAIN unit; IC3602) as the “L1M” signal via the buffer amplifier (MAIN unit; IC1301, pin 11). The signal passes through the low- pass filter (FILTER unit; L7036–L7038, C7033–C7039, C7041–C7045, C7049), and then applied to the RL7032.

•2–2.9999 MHz signal

The signal is applied to the relay (FILTER unit; RL7061) which is controlled by the band control IC (MAIN unit; IC3602) as the “L2M” signal via the buffer amplifier (MAIN unit; IC1301, pin 12). The signal passes through the low- pass filter (FILTER unit; L7066–L7068, C7063–C7084, C7086, C7087), and then applied to the RL7062.

•3–4.9999 MHz signal

The signal is applied to the relay (FILTER unit; RL7091) which is controlled by the band control IC (MAIN unit; IC3602) as the “L4M” signal via the buffer amplifier (MAIN unit; IC1301, pin 12). The signal passes through the low- pass filter (FILTER unit; L7096–L7098, C7094–C7096, C7098–C7101, C7105–C7107), and then applied to the RL7092.

•5–6.9999 MHz signal

The signal is applied to the relay (FILTER unit; RL7121) which is controlled by the band control IC (MAIN unit; IC3602) as the “L6M” signal via the buffer amplifier (MAIN unit; IC1301, pin 14). The signal passes through the low- pass filter (FILTER unit; L7126–L7128, C7124–C7132, C7136, C7137), and then applied to the RL7122.

•7–9.9999 MHz signal

The signal is applied to the relay (FILTER unit; RL7151) which is controlled by the band control IC (MAIN unit; IC3602) as the “L8M” signal via the buffer amplifier (MAIN unit; IC1301, pin 15). The signal passes through the low- pass filter (FILTER unit; L7066–L7068, C7063–C7084, C7086, C7087), and then applied to the RL7152.

•10–13.9999 MHz signal

The signal is applied to the relay (FILTER unit; RL7181) which is controlled by the band control IC (MAIN unit; IC3602) as the “L12M” signal via the buffer amplifier (MAIN unit; IC1301, pin 16). The signal passes through the low- pass filter (FILTER unit; L7182–L7184, C7183–C7188, C7193), and then applied to the RL7182.

Antenna

• RF FILTER CIRCUIT

power

detector

Transmitter signals

LPF

Filter: L0

from the PA unit.

1.6—1.9999 MHz

 

 

LPF

Filter: L1

 

2—2.9999 MHz

 

 

 

LPF

Filter: L2

 

3—4.9999 MHz

 

 

 

LPF

Filter: L3

 

5—6.9999 MHz

 

 

 

LPF

Filter: L4

 

7—9.9999 MHz

 

 

 

LPF

Filter: L5

 

10—13.9999 MHz

 

 

 

LPF

Filter: L6

 

14—19.9999 MHz

 

 

 

LPF

Filter: L7

 

20—29.9999 MHz

 

 

low-pass filter control signals from the MAIN unit

(L1M, L2M, L4M, L6M, L8M, L16M, L22M)

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