Repeater & Satellite

A single RS-UV3A cannot transmit and receive simultaneously. However, two RS-UV3As can be combined to create a full-duplex system for repeater or satellite communications.

Full Duplex Configuration

Hardware Setup

You’ll need:

• Two RS-UV3A boards
• Two antennas (with sufficient isolation)
• Shared power supply
• Audio interconnection between boards

Basic wiring:

RX Board	TX Board
RX Audio Out (DE-9 pin 4)	TX Audio In (DE-9 pin 1)
COR Out (DE-9 pin 5)	PTT (DE-9 pin 2)
Ground	Ground

The COR-to-PTT connection automatically keys the TX board when the RX board hears a signal.

Frequency Configuration

Repeater example (2m input, 70cm output):

RX Board:

FS146940        # 2m input frequency
TF10000         # 100.0 Hz CTCSS (input tone)
TM2             # Require tone to open squelch
SQ4             # Moderate squelch

TX Board:

FS446100        # 70cm output frequency
TF10000         # 100.0 Hz CTCSS (output tone) - optional
TM1             # Encode tone on TX
PW1             # High power

Repeater Features

The RS-UV3A includes several features specifically for repeater operation.

Hang Time

Keep the transmitter keyed briefly after the input signal drops:

HT1000          # 1000 ms (1 second) hang time
HT2000          # 2 second hang time
HT0000          # No hang time (immediate drop)
HT?             # Query current setting

Range: 0–5000 ms

CW Identification

FCC requires repeaters to identify at least every 10 minutes. Configure automatic CW ID:

CLWA2EUJ        # Set callsign (15 characters max)
IT600           # ID every 600 seconds (10 minutes)
CS15            # 15 WPM CW speed
CF0750          # 750 Hz CW tone

The CW ID is sent after the current transmission ends, not interrupting conversations.

Timeout Timer

Prevent stuck transmitters from tying up the repeater:

TO180           # 3 minute timeout
TG TIMEOUT      # Message to send on timeout

When a user exceeds the timeout, the repeater sends the timeout message in CW and unkeys.

Courtesy Beep

Signal users that the repeater is ready for the next transmission:

CB0             # No courtesy beep (default)
CB1             # Low tone beep
CB2             # High tone beep
CB3             # High/low beep
CB4             # Two-tone beep

The courtesy beep sounds after the hang time expires.

COR Inhibit

Prevent receiver squelch noise from keying the transmitter after TX drops:

CO0200          # 200 ms inhibit after TX

Complete Repeater Example

RX Board Configuration:

# Frequency and tones
FS146940        # Input frequency
TF10000         # 100.0 Hz CTCSS
TM2             # Tone squelch (require tone to access)

# Squelch
SQ4             # Moderate squelch
TSM             # Medium tone sensitivity

# Audio
VU18            # RX audio level (to TX board)
AF1             # Audio filter on

# Save settings
ST0

TX Board Configuration:

# Frequency and tones
FS146340        # Output frequency (600 kHz down)
TF10000         # 100.0 Hz CTCSS
TM1             # Encode tone on TX

# ID and timeout
CLWA2EUJ/R      # Repeater callsign
IT600           # ID every 10 minutes
CS15            # CW speed
TO180           # 3 minute timeout
TGTIME          # Timeout message

# Hang time and courtesy
HT1500          # 1.5 second hang time
CB2             # High tone courtesy beep
CO0150          # COR inhibit

# Power
PW1             # High power

# Save settings
ST0

Satellite Communications

For satellite work, configure one RS-UV3A for uplink and one for downlink.

Example for a 2m uplink / 70cm downlink satellite:

Uplink Board:

FS145980        # Uplink frequency
TM1             # Encode any required tone
PW1             # High power for satellite

Downlink Board:

FS435800        # Downlink frequency
SQ2             # Sensitive squelch
VU20            # Good volume for weak signals

Doppler Considerations

Satellite frequencies shift due to Doppler effect. You’ll need to adjust frequencies during the pass:

• Use a tracking program to calculate Doppler
• Send frequency commands via serial as the pass progresses
• Or use an Arduino to automate frequency updates

# Example Doppler correction commands
FR435804        # Adjust downlink as satellite approaches
FR435800        # Nominal at TCA
FR435796        # Adjust as satellite recedes

Cross-Band Repeat

A simpler configuration where you repeat between two bands:

2m to 70cm:

2m Board:

FS146520        # 2m simplex
COR Out → TX Board PTT
RX Audio → TX Board TX Audio

70cm Board:

FS446000        # 70cm simplex
TX triggered by 2m board COR

This allows extending range between a 2m mobile and a 70cm HT, for example.

Important Considerations

Antenna Isolation

For full-duplex operation, the TX and RX antennas must have sufficient isolation to prevent the TX signal from desensing or damaging the RX:

• Physical separation: Different poles, opposite sides of building
• Frequency separation: Different bands provide natural isolation
• Filtering: Cavity filters or duplexers for same-band operation

Same-Band Full Duplex

Operating a repeater with input and output on the same band (e.g., both 2m) requires expensive cavity duplexers. The RS-UV3A alone cannot provide sufficient isolation.

Power Supply

Both boards can share a power supply, but ensure adequate current capacity:

• Two boards: ~3.5W maximum during TX
• If using RS-UVPA amplifiers: plan for up to 30W total

Cooling

Extended TX duty cycles may require additional cooling. The RS-UV3A will read its temperature:

TP              # Read PCB temperature

If temperatures exceed 60°C, consider adding airflow or heatsinking.

Controller Integration

For more sophisticated repeater control, interface both RS-UV3As to a repeater controller or Raspberry Pi:

1. Connect both boards via USB (each gets its own COM port)
2. Use serial commands for:
   • Frequency changes
   • Power control
   • Status monitoring
   • Remote programming

This enables features like:

• DTMF remote control
• Internet linking (EchoLink, IRLP)
• Weather announcements
• Scheduled operations