1sec

LINEAR AFT

DEFEAT OUTPUT

MAN UP/DOWN

KEY PRESSED

MAN UP/DOWN

KEY RELEASED

Figure 12

PIN 16 : LINEAR AFT DEFEAT OUTPUT

This output is normally High and goes Low when a

Manual Up/Down command is issued.

It returns High with a 1 second delay from the

release of the key, in order to give the user the

possibility of the tuning adjustment without the AFT

intervention. It goes Low for 0.5s during program

change.

20

MEMORY

UP

DIGITAL

AFT ON

BAND

SEQ.

BAND

I

MEMORY

DOWN

AUTOMATIC

SEARCH

POWER

ON/OFF

BAND

III

VOLUME

UP

BAND

UHF

MAN SEARCH

DOWN

MAN SEARCH

UP

FT.

DOWN

FT.

UP

VOLUME

DOWN

BAND

CATV

19

18

AUTOMATIC

PRESET

MEMORY

ADDRESSING

STORE

MUTE

23

22

21

24

V1

V2

V3

X1

X2

X3

X4

Figure 13

PIN 17 : DIGITAL AFT ENABLE INPUT

AFT loop is always disabled. If pin 17 is left open

ically enabled at po wer on. When a manual

up/down search commandis issued, the digitalAFT

loop is disabled and the digital AFT status output is

inhibited.

The digital AFT loop is restored by the commands:

Digital AFT on/Automaticsearch/Automatic preset.

PINS 18-19-20-21-22-23-24 :

KEYBOARD MATRIX (see Figure 13)

A command is accepted if the corresponding con-

tact has been closed for a minimum time of 30ms.

Local input commands and I.R. commands have

the same priority.

If a complete I.R. command has been received, the

local inputs are blocked until the command has

been executed and the ”end of transmission code”

generated.

Viceversa an I.R. signal cannot be decoded until

an issued local command has been executed.

MEMORY UP/DOWN

Depressing one of these two commands, the mem-

ory position is stepped in the UP or DOWN direc-

tion.

If the key is kept closed, the channels are stepped

UP/DOWN every 0.5 second or every 5 commands

from the transmitter.

The memory locations 9 to 16 are jumped if pin 31

is at GND level.

BAND SELECTION

The bands can be selected either directly or with a

step-by-step command in the following sequence :

VHF I

CATV

VHF III

UHF

VHF I and so on

Only one band change is performed at each ac-

cepted command.

Disabled bands are automatically skipped. A band

can be disabled connecting the corresponding out-

M491B

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