Operating instructions

1892 1236 - SX500 Transmitter Operator Note - v1.6.1 / Apr 2005 5

PL3

NAME FUNCTION REMARKS

1 Transmit Enable < 0.5V = Transmit ON

(internal 20kO pullup)

2 DI Data Input Digital: DC coupled TTL compatible

3 AI Analogue Input Analogue : 750 mV p-p nominal

4 RSSI Received Signal

Strength Indication

RSSI: 0.5 - 2.0 V, 60dB dynamic range

(<33kO output impedance)

5 Squelch Open drain to <0.4V with 10kO load.

Low = No Signal

6 AF Audio Output 250mV p-p nominal

(~1kO output impedance)

Note inversion of audio from TX input to RX

output

7 DATA

O/P

Data output Open collector digital output

Note inversion of data from TX input to RX

output

8 +VOUT + 5 volt supply output VOUT= 50mA maximum current drain

9 0V 0 volts common ground

10 RS232

I/P

serial

programming

i/p

RS232 programming input

Note inverted TTL level data can also be

used.

If not used, leave not connected, or connect to

ground.

11 RB1

parallel frequency

select

internal pull-up to +5V, active low12 RB2

13 RB3

Table 3 PL3 Pin Connections