User's Manual
VOLTAGE CHART SST-442
24
Measurement Conditions
Supply voltage at 7.5 VDC, radio in operating mode,
volume control at minimum, power strobe enabled,
transmitter set for full power.
IMPORTANT: Because the SST-442 portable is
constructed with grounding sub-planes, use a system
ground in the same proximity as the circuit being
measured. All readings indicated as GND are true
system ground.
KEY: All measurements are in VDC unless indicated
otherwise.
NC = No connection
GND = Ground
* = Voltage is strobed in
Power Saver mode
→
= See note in right
column
REF PIN TX RX SB DESCRIPTION
CR101 1 0.7 0.0 0.0 TX/RX switching
2NCNCNC
3 GND GND GND
CR102 1 GND GND GND Voltage clamp
2 GND GND GND
30.00.0*
CR103 1 GND GND GND Noise detection
20.0→ * → amplified receiver
3 0.0 < 0.5 * noise
CR201 1 1.4 0.0 0.0 TX/RX switching
2NCNCNC
3 0.7 0.0 0.0
CR301 C 7.5 7.5 7.5 Over voltage protection
A GND GND GND
CR302 C 7.5 7.5 7.5 Reverse voltage
A 2.2 4.8 4.8 protection
CR303 1 6.8 6.8 6.8 Turn-on detection
2 4.2 4.2 4.2
3 6.1 6.1 6.1
CR304 1 2.0 4.7 4.7 PTT switching
2 2.2 4.7 4.7
3 2.4 5.0 5.0
CR305 1 GND GND GND Voltage clamp
2 5.0 5.0 5.0
3 0.0 0.0 0.0
CR306 1 2.4 2.4 2.4 Voltage clamp
2NCNCNC
3 2.4 2.4 2.4
CR307 C 7.5 7.5 7.5 Reverse volt protection
A0.0→ * → RX audio amp out
CR401 1 5.0 5.0 * Biasing
24.84.8*
3NCNCNC
REF PIN TX RX SB DESCRIPTION
CR402 1 GND GND GND VCO tuning
2NCNCNC
3 →→ * → 1.5 – 4.5 VDC
VCO tuning voltage
CR403 1 GND GND GND VCO modulation
2NCNCNC
32.42.4*
CR404 1 0.8 0.0 * TX/RX VCO switching
2NCNCNC
30.04.8*
IC101 1 0.0 4.7 * RX FM-IF subsystem
2NCNCNC
30.03.8*
40.04.7*
50.03.8*
60.03.8*
70.03.8*
80.04.7*
90.02.0*
10 0.0 0.6 *
11 0.0 2.4 *
12 0.0 0.0 *
13 NC NC NC
14 NC NC NC
15 GND GND GND
16 0.0 1.7 *
IC301 1 5.0 5.0 5.0 Microcontroller
20.05.05.0
35.00.00.0
40.00.00.0
50.00.00.0
60.00.00.0
70.00.00.0
80.00.00.0
9 →→→ → 0.0 V on Channel 1
10 0.0 0.0 * else 5.0 VDC
11 5.0 0.0 0.0
12 5.0 5.0 *
13 5.0 5.0 5.0
14 GND GND GND
15 5.0 5.0 5.0
16 4.2 4.2 4.2
17 5.0 5.0 5.0
18 2.4 2.4 *
19 0.0 0.5 *
20 5.0 5.0 5.0
21 → 2.4 * → 0-5 VDC tone
22 0.0 5.0 0.0 encode waveform
23 0.0 0.0 0.0
24 NC NC NC
25 0.0 0.0 0.0
26 NC NC NC
27 →→→ → 3.6 MHz clock signal
28 5.0 5.0 5.0
IC302 1 GND GND GND EEPROM
2 GND GND GND
3 GND GND GND
4 GND GND GND
50.00.00.0
60.00.00.0
7 GND GND GND
85.05.05.0
1
2
3
SOT-23