LA1805 Ver la hoja de datos (PDF) - SANYO -> Panasonic

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LA1805

AM/FM-IF/MPX Tuner System for Radio-Casette Recorders, Music Centers

SANYO -> Panasonic 

LA1805

2. VCO Stop

The VCO is so designed as to stop automatically at the

AM mode.

(when pin 11 and pin 21 are at the same potential)

There is no pin available for stopping the VCO at the

FM mode. However, the method shown right can be

used to stop the VCO at the FM mode, causing the

forced monaural mode to be entered.

Make the wiring as

short as possible.

3. Free-running frequency measurement and adjustment

Either of the following two methods is used to measure the

free-running frequency.

(1) Connect pin 13 to a frequency counter through the high

input impedance amplifier.

(2) Connect the connection point of the semifixed resistor

connected to pin 13 and the fixed resistor to a frequency

counter through the resistor of 240kΩ or greater.

Figure 4

Figure 5

Figure 6

How the error changes with the resistor value is

shown in Figure 7.

IF input 100dBµ

Nonmodulation

Resistor value, RX – kΩ

• When setting the free-running frequency, the following must be noted.

Figure 7

Apply a 10.7MHz 100dBµ nonmodulation carrier as IF input signal and set to 76kHz±50Hz with the tuning indicator

lighted.

4. Separation setting capacitor Cs

The separation characteristic for the LA1805 alone

(IF input) differs from that for the antenna input

with a front end. This difference is caused by the

characteristics of the front end and ceramic filter.

Shown right is how the separation characteristic

changes with the separation setting capacitor value

when the LA1186N is used as front end. Referring

to this separation characteristic, choose the

optimum separation for your set model.

Free-running frequency, fF – kHz

Figure 8

No.2887-4/13

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