Circuit Description; Receive Circuits; Rf Circuits; Vhf Band - Icom IC-2730A Service Manual

Dual band transceiver

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Table Of Contents

Table of Contents

SECTION 4.

4-1 RECEIVE CIRCUITS

RF CIRCUITS

The received signal from the antenna connector passed

through the LPF (L90, L94, L96, C409, C418 and C428). The

ﬁ ltered signal is applied to either the VHF or UHF band's RF

circuit.

VHF BAND (118–174 MHz)

The received VHF band signal from the LPF (L90, L94, L96,

C409, C418 and C428) is passed through the LPF (L79, L83,

L87, C378, C386 and C394) and TX/RX SW (D66, D69 to

D71 and D77), and applied to the PRE-AMP (Q24).

• Left band

The ampliﬁ ed signal is passed through the attenuator (D34)

and tuned BPF (D28, D88, L31, L34, C119, C127, C128 and

C135), and applied to the RF AMP (Q20). The ampliﬁ ed sig-

nal is passed through the tuned BPF (D20, D87, L10, L18,

C60, C71, C74, C79 and C86), and then applied to the 1st

mixer (Q145).

• Right band

The ampliﬁ ed signal is passed through the attenuator (D33)

and tuned BPF (D27, D85, L23, L32, L33, C116, C125, C126

and C132), and applied to RF AMP (Q19). The ampliﬁ ed sig-

nal is passed through the tuned BPF (D19, D86, L9, L17,

C57, C69, C70, C77 and C84), and then applied to the 1st

mixer (Q143).

UHF BAND (375–550 MHz)

The received UHF band signal from the LPF (L90, L94, L96,

C409, C418 and C428) is passed through the HPF (L84, L88,

C392, C395 and C429), TX/RX SW (D68, D73, D75, D84,

L86, L92, C387, C396 and C413), and applied to the PRE-

AMP (Q23).

• Left band

The ampliﬁ ed signal is passed through the attenuator (D32)

and tuned BPF (D22, D24, D26, D30, L21, L28 and L101),

and applied to the RF AMP (Q18). The ampliﬁ ed signal is

passed through the tuned BPF (D12, D16, D91, D92, L4,

L12, L16, L102, C33, C65 and C67), and then applied to the

1st mixer (Q146).

• Right band

The ampliﬁ ed signal is passed through the attenuator (D31)

and tuned BPF (D21, D23, D25, D29, L22, L27 and L99), and

applied to the RF AMP (Q17). The ampliﬁ ed signal is passed

through the tuned BPF (D11, D15, D89, D90, L3, L11, L15,

L100, C32, C63 and C66), and then applied to the 1st mixer

(Q144).