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Bluetooth TNC Guide

Android Only: Bluetooth TNC connections are currently only available on Android devices.

Connect APRS Chat directly to a Bluetooth-enabled TNC for portable RF operations without needing a computer or network connection.

Supported TNCs

APRS Chat supports the following Bluetooth TNCs:

  • Mobilinkd TNC3

    Full-featured TNC with built-in Bluetooth. Recommended choice.

  • Mobilinkd TNC2

    Previous generation, still fully supported.

  • Other KISS-compatible Bluetooth TNCs

    Any TNC that presents a Bluetooth Serial Port Profile (SPP) with KISS protocol.

Step-by-Step Setup

  1. 1. Pair Your TNC

    Before using APRS Chat, pair your TNC with your Android device:

    1. Turn on your TNC and put it in pairing mode
    2. Go to Android Settings → Bluetooth
    3. Find your TNC in the available devices list
    4. Tap to pair (PIN is usually 1234 or 0000)

  2. 2. Grant Permissions

    APRS Chat needs Bluetooth permissions to connect to your TNC:

    • Bluetooth (required)
    • Nearby devices (Android 12+)
    • Location (may be required for Bluetooth scanning)

  3. 3. Configure APRS Chat

    Navigate to Settings → Connection → Bluetooth TNC

    • Tap Select Device
    • Choose your paired TNC from the list

  4. 4. Configure TNC Settings

    If your TNC requires specific settings, configure them in the TNC options:

    • TX Delay: Usually 300-500ms (adjust based on your radio)
    • TX Tail: Usually 50-100ms
    • Audio levels: May need adjustment for your specific radio

  5. 5. Connect

    Tap Connect. The app will establish a Bluetooth connection to your TNC. You should see the TNC's status LED change to indicate an active connection.

Mobilinkd TNC Configuration

For Mobilinkd TNCs, you can also configure audio levels directly from APRS Chat:

  1. Connect to your TNC
  2. Go to Settings → TNC Configuration
  3. Adjust input and output levels as needed
  4. Use the built-in audio test tone for calibration

Troubleshooting

  • TNC not appearing in device list:
    • Ensure Bluetooth is enabled on your phone
    • Verify the TNC is powered on and in range
    • Try re-pairing the device in Android settings
  • Connection drops frequently:
    • Keep the TNC close to your phone (within 10 meters)
    • Ensure TNC battery is sufficiently charged
    • Disable battery optimization for APRS Chat
  • Not receiving packets:
    • Check that your radio is tuned to an APRS frequency (144.390 MHz in NA)
    • Verify audio cable connections between TNC and radio
    • Adjust TNC input audio levels
  • Transmitted packets not heard:
    • Verify PTT is triggering on your radio
    • Adjust TX delay if packets are being cut off
    • Check TNC output audio levels

Still having issues? Submit a support ticket