1. Introduction
This manual provides comprehensive instructions for the installation, operation, and maintenance of your BAFOVY HDM66 HD Modulator. The HDM66 is designed to convert HD multimedia interface signals into RF signals for distribution within a local CATV system, allowing older televisions to display modern HD sources. It features PLL control for stable VHF operating frequency, HD input, and A/V output, ensuring reliable performance and compatibility with NTSC and PAL TV formats.
2. Product Overview
The BAFOVY HDM66 HD Modulator is a compact and durable device constructed from ABS material, ensuring a long service life. It offers high-definition output with support for 1080p, 1080i, 720p, 576p, 576i, and 480p resolutions. The modulator is designed for ease of use, requiring no driver installation, making it portable and flexible for various home setups.

Figure 2.1: Front view of the HDM66 HD Modulator, showing the A/V output ports (yellow for video, white for left audio, red for right audio) and the RF modulator switch (CH3/CH4, ON/OFF).

Figure 2.2: Angled view of the HDM66 HD Modulator, highlighting the RF IN and RF OUT coaxial ports, along with the A/V output and RF modulator switch.
3. Specifications
| Model | HDM66 |
| Material | ABS |
| TV Standard Format | PAL/NTSC |
| Frequency Range (PAL) | 55.25MHz / 62.25MHz |
| Frequency Range (NTSC) | 61.25MHz / 67.25MHz |
| Output Level | 80±5dBuV |
| Sound System | M=4.5MHz, B=5.5MHz |
| Input Port | HD Multimedia Interface |
| Output Port | Female Header (A/V) |
| RF Input | F Female |
| RF Output | F Female |
| Input Resolution Support | 1080P / 1080I / 720P / 576P / 576I / 480p |
| HD Multimedia Interface Version | 1.3 |
| HDCP Version | 1.3 |
| Input Voltage/Current | DC 5V/500mA (min) |
| Operating Temperature | 0°C ~ +40°C |
| Product Dimensions | 7.87 x 5.51 x 1.57 inches |
| Item Weight | 4.9 ounces |
4. Setup Instructions
4.1. Package Contents
Before proceeding with the setup, please ensure all items are present in the package:
- 1 x HDM66 Modulator
- 1 x Power Cord (USB)
4.2. Connection Guide
Follow these steps to connect your HDM66 HD Modulator:
- Connect the USB power adapter: Plug the provided USB power cord into the DC 5V INPUT port on the modulator and connect the other end to a suitable USB power source (e.g., a wall adapter or TV USB port).
- Set the RF Modulator switch: Locate the RF MODULATOR switch on the device. Set the channel to either CH3 or CH4, and ensure the switch is in the ON position. If set to OFF, the RF output will not function.
- Connect RF input and output: Connect your antenna or cable TV RF input to the RF IN port. Connect the RF OUT port to your television's RF input using a coaxial cable.
- Connect HD Multimedia Interface device: Power on your HD Multimedia Interface source device (e.g., DVD player, game console, set-top box) and connect its HD Multimedia Interface output to the HD Multimedia Interface INPUT port on the modulator.
- Turn on the TV: Power on your television and tune it to the corresponding channel (CH3 or CH4) that you selected on the modulator.

Figure 4.1: Rear view of the HDM66 HD Modulator, showing the DC 5V INPUT for power and the HD Multimedia Interface INPUT port.

Figure 4.2: Angled view of the HDM66 HD Modulator, illustrating the DC 5V INPUT and HD Multimedia Interface INPUT ports for connecting source devices and power.
5. Operating Instructions
Once the HDM66 HD Modulator is correctly set up and connected, operating it is straightforward:
- Power On: Ensure the modulator is powered on via the USB connection and the RF MODULATOR switch is set to ON.
- Source Device: Turn on your HD Multimedia Interface source device (e.g., DVD player, game console).
- Television Channel: Tune your television to the channel (CH3 or CH4) that matches the setting on the modulator. The video and audio from your HD Multimedia Interface source should now be displayed on your TV.
- A/V Output: If you are using the A/V output, connect the yellow (video), white (left audio), and red (right audio) RCA cables from the modulator's A/V OUT ports to the corresponding input ports on your display device or audio receiver.
6. Maintenance
To ensure the longevity and optimal performance of your BAFOVY HDM66 HD Modulator, follow these simple maintenance guidelines:
- Cleaning: Use a soft, dry cloth to clean the exterior of the device. Avoid using liquid cleaners, aerosols, or harsh chemicals, as these can damage the casing or internal components.
- Ventilation: Ensure the modulator is placed in a well-ventilated area to prevent overheating. Do not block any ventilation openings.
- Storage: When not in use for extended periods, store the device in a cool, dry place away from direct sunlight and extreme temperatures.
- Connections: Periodically check all cable connections to ensure they are secure and free from damage.
7. Troubleshooting
If you encounter issues with your HDM66 HD Modulator, refer to the following common problems and solutions:
- No Picture/Sound on TV:
- Ensure the modulator is powered on and the power cord is securely connected.
- Verify that the RF MODULATOR switch is set to ON and the correct channel (CH3 or CH4) is selected.
- Check that your TV is tuned to the same channel (CH3 or CH4) as the modulator.
- Confirm that the HD Multimedia Interface source device is powered on and outputting a signal.
- Inspect all HD Multimedia Interface and RF cable connections for looseness or damage.
- Poor Picture Quality:
- Ensure all cables are securely connected and not damaged.
- Minimize interference from other electronic devices.
- If using a long coaxial cable, consider using a higher quality, shielded cable.
- No Audio:
- Check the audio settings on your HD Multimedia Interface source device.
- Ensure the A/V output cables (white and red RCA) are correctly connected if you are using them.
- Verify the TV's volume is not muted or set too low.
8. Warranty and Support
BAFOVY products are manufactured with quality and reliability in mind. For specific warranty information, please refer to the documentation provided at the time of purchase or contact your retailer. For technical support or further assistance, please reach out to the BAFOVY customer service team through the contact information provided on the official BAFOVY website or your purchase platform.