BLE TNCs

Newer TNCs — the Mobilinkd TNC4 in LE mode, the B.B. Link — speak KISS over Bluetooth Low Energy. APRS Connect supports them as their own channel type, and the setup is genuinely different from Bluetooth Classic: there is nothing to pair.

BLE is not the paired list

A BLE TNC is connected to directly, so there is nothing to pair — and it never appears in Android's Bluetooth settings at all. An empty paired list does not indicate a problem. The way to find one is to listen for it advertising, which is what the app's scan does.

A Mobilinkd TNC4 does both Classic and LE: it has to be switched into LE mode (in the Mobilinkd configuration) to be found here. In Classic mode, use the Bluetooth TNC channel type instead.

Add the channel

1. Open the Radio screen (under More on the tab bar) and tap Add channel.
2. Pick Bluetooth LE TNC — "A BLE KISS TNC — Mobilinkd TNC4 in LE mode, B.B. Link".
3. Switch the TNC on and keep it nearby. The Nearby devices section starts listening; a scan runs for about 20 seconds, and SCAN starts another whenever you want one.
4. Devices appear as the scan hears them, each with its address and signal strength. Likely TNCs — recognised by the BLE KISS service they advertise, or by name — are sorted first and tagged LIKELY TNC; among the rest, the strongest signal sorts first, which is usually the device next to the phone.
5. Tap your TNC. The channel connects, and if you haven't named it yet it adopts the device's name.

The first time through, Android asks for the nearby-devices (Bluetooth) permission. On phones below Android 12 there's an extra system quirk: Location has to be switched on for any BLE scan to return results — Bluetooth on its own is not enough, and the app tells you when this is the problem rather than showing an empty list.

As with the other radio types, one BLE link is live at a time — choosing a device stands down any other BLE channel. A BLE channel runs happily alongside a Bluetooth Classic channel, though: they are separate radios' links.

When the TNC doesn't appear

"Nothing heard. Switch the TNC on and bring it close, then scan again." — and if that doesn't do it:

• It may be connected to something else. A BLE device stops advertising while it is connected, so a TNC4 still linked to another app or another phone is invisible to a scan. Disconnect it there (or power-cycle the TNC) and scan again.
• Check it's in LE mode. A TNC4 in Classic mode advertises nothing a BLE scan can see.
• Already yours? The device this channel is pointed at stays in the list — marked CHOSEN — even when a scan doesn't hear it, precisely because a TNC that's off, out of range, or already connected to this phone doesn't advertise. A working channel isn't made to look unconfigured by a silent scan.

Settings and status

The channel gets the same Transmit delay setting as every channel that keys a radio — the tone sent before the data. A hardware TNC with its own transmit-delay setting may use that one instead of the app's.

Once connected, the channel row on the Radio screen reports honestly: received and sent counters, CONNECTED · QUIET when the link is up but the frequency is silent, and "check the radio is in KISS mode" advice when it connects but never hears anything. See Connect a radio for how channel status works everywhere.

Next steps

• Send your first beacon — over RF, through the TNC4.
• Background & battery — keep the link up with the screen off.
• Connect a radio — all six channel types compared, including USB for the same TNC4 on an OTG cable.

Last updated 31 August 2026