Kenwood Comprehensive Guide to Marine Radio Features and Functions

TS-440S

CIRCUIT DESCRIPTIO N

VsF is compared with voltage from IC8 pin 6 (5 .5 V) . When SWR increases, VSF lowers and the voltage leve l of IC8 pin 8 rises . At IC7 pin 3, a triangular wave is moni - tored . The triangular wave is compared with the wav e from IC8 pin 8 and output . The triangular wave is con- verted to a square wave by IC10 and sent to switch Q 3 and Q4 . This voltage is used as the SWR control voltage .

Output voltage from IC8 pin 2 consists of the voltage com - pared with VsR/Vs F and + 5 DC voltage . It is distribute d to IC4 the level shift/meter amplifier to move the needl e in the SWR meter and IC5 the V-I convertor to control th e AT440 .

VR14 is used to adjust the SWR meter ZERO point . VR 13 is for SWR meter adjustmen t

3) FULL/SEMI BREAK-IN and VOX circuits

		RL TXB RX B
MICROPROCESSOR	STAND-B Y	CONTRO L
	CIRCUIT	POWER SUPPLY
CONTRO L
CIRCUIT
KEYIN G
CIRCUI T

VO X

CIRCUIT

Fig . 9-1 FULL/SEMI BREAK-IN block diagra m

When the standby switch, the key, or the VOX switchin g transistor are activated, a ground is applied to the input pi n of the control circuit, which causes a standby signal to b e fed to the microprocessor to determine if a valid transmit con - dition has been met . When that condition has been met, th e

KEYIN G

STAND-B Y

VOX

standby circuit in the IF unit will be turned on .

A keying signal is generated by the control circuit, wheneve r the key is depressed, to control the keying circuits in the I F unit . This keying signal is also used as the transmit/receiv e signal during break-in operations .

o KEYING (FULL)

o CONTROL( FULL )

o KEYING(SEMI )

0 CONTROL(SEMI )

Fig . 9-2 FULL/SEMI BREAK-IN timing chart

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