14. Stop Detector Adjustment

Although this explanation is for the LA1137N, it is identical for the LA1136N, except that the pin numbers are different.

The LA1137N is designed for use with the following microcontrollers.

Stop detection method: LM7001 (Sanyo) (SD output only)

IF count method:

LM7000 (Sanyo)

LC7230 (Sanyo)

(1) Support for the LM7001

The search stop detector uses the active HIGH signal of pin18.

The IF signal from the IF amplifier is detected, on pin 16 the signal that determined the bandwidth characteristics through the

narrowband filter BFU450CN (BFU450CN is equivalent to the amplifier emitter load) is detected, and the S-meter output is

has the following relationship with the S-meter load R17.

In the above example, 3 k

Ω is changed to 4.5 kΩ, but the R ratio of the output is 1.5x. However, the meter output has an upper

comparing the S-meter output described above with the reference voltage Vref on pin 9 (400 µ

× R9). Using the

recommended constants, Vref = 400 µ

× 2.4 k = 1.0 (V).

The comparator compares the electric potential of pin 17 with that of pin 9 and detects when the electric potential of pin 17

is greater than that of pin 9, in which event the transistor is turned off and the SD output changes from LOW to HIGH (GND

Note that, in consideration of differences in circuit configurations, Vref should be at least 0.7 V.

Antenna input – dBµ

S-meter load

Unit (capacitance: F)

Ω

Ω

Ω

LA1136N, 1136NM, 1137N, 1137NM

No. 3507-18/28