Voice Operation

This guide covers setting up the RS-UV3A for voice communications, including simplex operation, repeater access, and tone squelch configuration.

Basic Voice Setup

For voice operation you need:

Antenna connected to SMA jack
Power via USB or VIN
Speaker connected to SPKR pads or SPK/MIC jack
Microphone (electret) connected to MIC pad
PTT switch connected to PTT pad

Setting Frequencies

Simplex Operation

For simplex (same frequency TX and RX), use the FS command:

FS146520        # 146.520 MHz (2m FM calling)
FS223500        # 223.500 MHz (1.25m FM calling)
FS446000        # 446.000 MHz (70cm FM calling)

Repeater Operation (Split Frequencies)

Use the FD (down) or FU (up) commands for standard repeater offsets:

FD146940        # RX 146.940, TX 146.340 (600 kHz down)
FU147060        # RX 147.060, TX 147.660 (600 kHz up)

Standard offsets by band:

2m: ±600 kHz
1.25m: ±1600 kHz
70cm: ±5000 kHz

For non-standard splits, set TX and RX separately:

FR146940        # Set RX frequency
FT146340        # Set TX frequency

Volume and Audio

Receiver Volume

The volume can be adjusted two ways:

Hardware: Turn VR1 potentiometer on the board
Software: Use the VU command (0–39, in 1 dB steps)

VU15            # Set volume to 15 (recommended for DTMF decode)
VU20            # Increase volume
VU?             # Query current volume

Audio Filters

The RS-UV3A has switchable audio filters:

Command	Filter	Passband
`AF1`	Low-pass ON	300–2500 Hz
`AF0`	Low-pass OFF	300–5500 Hz
`HP1`	High-pass ON	Higher low corner
`HP0`	High-pass OFF	Lower low corner

For natural-sounding voice, use the defaults (AF1, HP1). For data modes, you may want wider audio (AF0).

Microphone Gain

Adjust microphone sensitivity with the GM command:

GM10            # Default gain (10)
GM15            # Maximum gain
GM05            # Lower gain for hot mics
GM?             # Query current setting

Range is 0–15 in 2 dB steps.

Squelch Settings

RSSI Squelch

The basic squelch uses received signal strength:

SQ3             # Default, opens on moderate signals
SQ0             # Always open (listen to noise)
SQ9             # Very tight (strong signals only)
SQ?             # Query current level

For extended range (weak signal work), enable high squelch range:

SR1             # Add 30 dB to squelch setting
SR0             # Normal range (default)

Checking Squelch Status

Query whether the squelch is currently open:

SO              # Returns SO: 0 (closed) or SO: 1 (open)

Tone Squelch (CTCSS/PL)

Many repeaters require CTCSS (Continuous Tone-Coded Squelch System) tones.

Setting the Tone Frequency

TF10000         # 100.0 Hz (multiply desired Hz by 100)
TF13180         # 131.8 Hz
TF08850         # 88.5 Hz
TF?             # Query current tone

Common CTCSS frequencies: 67.0, 71.9, 74.4, 77.0, 79.7, 82.5, 85.4, 88.5, 91.5, 94.8, 97.4, 100.0, 103.5, 107.2, 110.9, 114.8, 118.8, 123.0, 127.3, 131.8, 136.5, 141.3, 146.2, 151.4, 156.7, 162.2, 167.9, 173.8, 179.9, 186.2, 192.8, 203.5

Tone Mode

Control when tones are transmitted/required:

TM0             # Off (default)
TM1             # TX only (encode tone on transmit)
TM2             # TX and RX (encode + tone squelch)

TM1: Use when the repeater requires a PL tone to access but you want to hear all traffic
TM2: Use when you only want to hear stations with your tone (tone squelch)

Tone Squelch Sensitivity

If tone squelch is unreliable:

TSL             # Low sensitivity (default)
TSM             # Medium sensitivity
TSH             # High sensitivity

Transmitting

Manual PTT

Ground the PTT pad or press the button on a speaker-mic. The TX LED illuminates during transmission.

Software Control

Transmit via serial command:

TX1             # Transmit with 1 minute timeout
TX2             # Transmit with 2 minute timeout
TX5             # Transmit with 5 minute timeout
TX0             # Stop transmitting immediately

Timeout Timer

Prevent excessive transmissions with the timeout timer:

TO120           # 120 second (2 minute) timeout
TO300           # 5 minute timeout
TO000           # Disable timeout
TO?             # Query current setting

When timeout occurs, the RS-UV3A sends a configurable CW message and unkeys:

TG TO           # Set timeout message to "TO"
TGTIME          # Set timeout message to "TIME"

TX Power

The RS-UV3A has two power levels:

PW1             # High power (~200 mW, 23 dBm)
PW0             # Low power (~10 mW, 10 dBm)
PW?             # Query current setting

VOX Operation

The RS-UV3A includes voice-operated transmit (VOX):

VX1             # Enable VOX
VX0             # Disable VOX (default)
VL0             # High sensitivity
VL1             # Medium sensitivity (default)
VL2             # Low sensitivity

Don’t use VOX with speaker-mic

VOX will key the transmitter when it hears audio from the speaker. Only use VOX with headphones or when the speaker is isolated from the microphone.

Pre/De-emphasis

For standard FM voice, keep pre-emphasis and de-emphasis enabled:

DP1             # Enabled (default)
DP0             # Disabled (for some data modes)

Signal Monitoring

Read current signal conditions:

SS              # Signal strength in dBm
SN              # Noise level (lower = cleaner signal)
SO              # Squelch state (0 = closed, 1 = open)

Complete Voice Setup Example

Setting up for a typical 2m repeater (146.94 MHz, -600 kHz offset, 100.0 Hz PL):

FD146940        # 146.94 RX, 146.34 TX
TF10000         # 100.0 Hz CTCSS
TM1             # Encode tone on TX only
SQ4             # Moderate squelch
VU18            # Comfortable volume
PW1             # High power
TO180           # 3 minute timeout
ST0             # Save as power-on default

Then to recall these settings after power-up:

RC0             # Not needed if saved as defaults

Or save to a memory channel:

ST1             # Save to channel 1
RC1             # Recall channel 1