1. Introduction
This manual provides detailed instructions for the safe and efficient operation of your CASTOR iBELL FM820BT Portable FM Radio. This device features a Bluetooth speaker, a rechargeable battery, and supports USB and SD card MP3 playback. Please read this manual thoroughly before use and retain it for future reference.
2. Product Features
- Portable Table Top FM Radio with 3-Band tuner (FM/AM/SW).
- Integrated Bluetooth Speaker for wireless audio streaming.
- USB port and SD Card Slot for MP3 audio file playback.
- Built-in dynamic speaker for clear audio output.
- Telescopic antenna for enhanced radio reception.
- High sensitivity receiver for improved signal capture.
- Built-in rechargeable battery for portable use.
3. Package Contents
- CASTOR iBELL FM820BT Portable FM Radio Unit
- Rechargeable Battery (pre-installed or separate)
- C-Type Charging Cable
4. Controls and Components

Figure 4.1: Front Panel Controls
This image displays the front of the radio, highlighting the mode button, previous/next track buttons, and the tuning knob. The frequency display for FM, AM, and SW bands is also visible.

Figure 4.2: Side Panel Ports and Controls
This image shows the side of the radio, detailing the Volume knob, Power ON/OFF switch, DC 5V IN (C-Type Charging Port), Charge Indicator, Mode Selector (Music/FM/AM/SW), USB Port, and SD Card Slot.
- Power ON/OFF Switch: Located on the side, slides to turn the unit on or off.
- Volume Knob: Rotates to adjust the audio output level.
- Mode Button: Cycles through available modes: FM, AM, SW, Bluetooth, USB, SD.
- Previous/Next Buttons: Used for navigating tracks in MP3 mode or scanning stations in radio mode.
- Tuning Knob: Rotates to manually tune radio frequencies.
- Telescopic Antenna: Extends for improved radio signal reception.
- USB Port: For connecting USB flash drives to play MP3 files.
- SD Card Slot: For inserting SD cards to play MP3 files.
- DC 5V IN (C-Type Charging Port): Connects the charging cable for battery recharge.
- Charge Indicator: LED light indicating charging status.
5. Setup
5.1. Initial Charging
Before first use, fully charge the radio's built-in rechargeable battery. Connect the provided C-Type charging cable to the DC 5V IN port on the side of the radio and the other end to a compatible USB power adapter (not included). The charge indicator light will illuminate during charging. Once fully charged, disconnect the cable.
5.2. Powering On/Off
Slide the Power ON/OFF switch located on the side of the unit to the 'ON' position to power on the radio. Slide it to the 'OFF' position to power off.
6. Operating Instructions
6.1. Radio Mode (FM/AM/SW)
- Power on the radio.
- Press the 'MODE' button repeatedly until the desired radio band (FM, AM, or SW) is selected.
- Extend the telescopic antenna for optimal FM and SW reception. For AM, the internal antenna is generally sufficient.
- Rotate the 'TUNING' knob to scan for radio stations.
- Adjust the 'VOLUME' knob to your preferred listening level.
6.2. Bluetooth Mode
- Power on the radio.
- Press the 'MODE' button until 'Bluetooth' mode is announced or indicated. The radio will enter pairing mode.
- On your mobile device, enable Bluetooth and search for available devices.
- Select 'FM820BT' from the list of devices to pair. A confirmation sound will indicate successful pairing.
- You can now play audio from your device through the radio's speaker. Use the radio's Previous/Next buttons or your device to control playback.
6.3. USB/SD Card MP3 Playback
- Power on the radio.
- Insert a USB flash drive into the 'USB' port or an SD card into the 'SD CARD SLOT' with MP3 audio files.
- The radio should automatically switch to USB or SD mode and begin playing the MP3 files. If not, press the 'MODE' button to select the correct source.
- Use the Previous/Next buttons to skip tracks.
7. Maintenance
- Keep the unit dry. Avoid exposure to water or high humidity.
- Clean the exterior with a soft, dry cloth. Do not use abrasive cleaners or solvents.
- Do not attempt to disassemble the unit. Refer all servicing to qualified personnel.
- Store the radio in a cool, dry place when not in use for extended periods.
8. Troubleshooting
| Problem | Possible Cause | Solution |
|---|---|---|
| No power | Battery discharged; Power switch off. | Charge the battery; Slide power switch to ON. |
| Poor radio reception | Antenna not extended; Weak signal; Interference. | Extend the telescopic antenna; Reposition the radio; Try tuning manually. |
| Bluetooth not connecting | Radio not in Bluetooth mode; Device too far; Already paired with another device. | Ensure radio is in Bluetooth mode; Move device closer; Disconnect from other devices. |
| USB/SD playback not working | Incorrect file format; USB/SD card not inserted correctly; Corrupted files. | Ensure files are MP3 format; Reinsert USB/SD card; Try a different USB/SD card. |
9. Specifications
| Feature | Detail |
|---|---|
| Brand | CASTOR |
| Model Number | FM820BT |
| Color | BLACK |
| Connectivity Technology | Bluetooth, USB |
| Product Dimensions (L x W x H) | 18.5L x 7W x 12.5H Centimeters |
| Weight | 800 Grams |
| Tuner Type | AM, FM |
| Radio Bands Supported | 3-Band (FM/AM/SW) |
| Power Source | Battery Powered (Rechargeable) |
| Display Type | LED |
| Hardware Interface | USB |
10. Warranty and Support
The CASTOR iBELL FM820BT comes with a 1-Year Warranty. This includes a 6-month standard warranty and an additional 6-month warranty upon free registration. Registration should be completed within 30 days from the date of purchase.
For warranty claims or technical support, please contact the manufacturer at:
- Manufacturer Contact: 1800-2020-860
- Warranty Support: 1800-2020-260




