Audio Troubleshooting
Edit on GitHubDiagnosing the beacon's audio: silent buzzer, distorted jack output, and the level checks for recording and radio bridging.
Audio Troubleshooting
The audio path has two ends: the buzzer inside the case and the jack outside it. Each has its own failure signature.
Buzzer faults
| Symptom | Likely cause |
|---|---|
| Totally silent | Wiring, or the tone feature disabled |
| Quiet | Series resistor too large, or low battery |
| Rattles | Buzzer touching the case wall |
| Works then stops | Cold solder joint on the buzzer leads |
Jack faults
| Symptom | Likely cause |
|---|---|
| No sound on the recording | Mono vs stereo plug mismatch, or the isolation diode |
| Distorted | Level too hot for the recorder input |
| Crackling | Dry solder at the jack lugs |
| Works with headphones, not a recorder | Recorder input expects line level, not speaker level |
The levels
The beacon’s audio is a 3.3 V square wave: far too hot for most recorder mic inputs. The honest fix:
- Use the jack into the mic input of a handheld radio with its gain turned down.
- Or record at a distance, not plugged in.
- Or add a fixed pad (two resistors) at the jack.
The Audio Tone Details page has the frequency and level specs.
The isolation diode
The jack circuit includes a diode so the buzzer still sounds when a plug is inserted. If the buzzer dies exactly when you plug in the cable, the diode is reversed or shorted. Check it with the multimeter’s diode test.
The capture test
- Plug into a recorder.
- Play a test burst (transmit or tone test).
- The recording should decode by ear or with software (see Reading CW by Ear).
- A recording that decodes on the bench but not through a radio means the radio’s mic gain is clipping: turn it down.
Related pages
- Audio Tone Details for the specs
- Audio Jack Wiring for the circuit
- Transmitter Testing for the full-path test