HDMI over CAT6 Extender Kit - 4K 60Hz

HDMI® Balun Kit | HDR | 4:4:4 | 7.1 Audio Support | 165 ft. (50 m)

Product ID: ST121HD20V

3 stars (1 reviews) |
  • Crystal-clear picture quality with support for resolutions up to 4K 60Hz
  • Compatible with HDR and 4:4:4 chroma subsampling for lifelike images
  • Hassle-free setup with long-distance transmission over a reliable connection
Your price

This HDMI over CAT6 extender lets you transmit your 4K 60Hz signal up to 165 ft. (50 m) over a single CAT6 cable, with the added benefit of a local HDMI output. The extender supports High Dynamic Range (HDR), providing high contrast images with enhanced video.

Astonishing 4K Picture Quality

This HDMI Ethernet extender supports a 4K 60Hz (3840 x 2160) resolution, providing four times the picture quality of high-definition (1080p). The extender supports HDMI 2.0 capabilities, offering 4:4:4 chroma subsampling. This ensures a crystal-clear picture that's ideal for delivering video content. With HDR support, you can enjoy increased contrast, color brightness and greater luminosity in your images.

Long-Distance Transmission

Extend an HDMI signal to up to 165 ft. (50 m) with the HDMI to CAT6 converter. Use your existing CAT6 cable infrastructure with a direct connection to the converter for an easy run through walls and ceilings, saving you on installation costs.

Compatible with HDCP 2.2 Devices

Connect your HDMI 2.0 devices and displays with confidence, knowing this extender is HDCP 2.2 compliant. This lets you harness the capabilities of HDMI-enabled devices such as Blu-ray players or online streaming devices in higher resolutions. It is also backward compatible with previous generations of HDMI and HDCP.

ST121HD20V is backed by 2-year StarTech.com warranty with free lifetime technical support.


  • Extend your HDMI signal in classrooms and boardrooms
  • Use existing CAT6 infrastructure to create digital signage
  • Distribute an HDMI signal to multiple displays at tradeshows
  • Extend your HDMI signals to locations that lack power outlets

Partner Numbers

  • UPC 065030880084


Warranty Information Warranty 2 Years
Connector(s) 2 - Connector A HDMI (19 pin)
1 - Connector A RJ-45
1 - Connector B RJ-45
HDMI (19 pin)
Environmental Operating Temperature 0°C to 40°C (32°F to 104°F)
Storage Temperature -20°C to 60°C (4°F to 140°F)
Humidity 0% - 80 % RH (non-condensing)
Hardware AV Input HDMI
AV Output HDMI
Cabling Cat 6 UTP
Audio Yes
Packaging Information Package Height 2.8 in [70.0 mm]
Package Length 8.7 in [22.0 cm]
Shipping (Package) Weight 27.4 oz [777.0 g]
Package Width 5.1 in [13.0 cm]
Performance Maximum Cable Length 165.0 ft [50.3 m]
Max Distance 50 m / 165 ft
Maximum Digital Resolutions 3840 x 2160 (4K) @ 60 Hz
Supported Resolutions 3840x2160 (4K) 60Hz
2560x1600 60Hz
1920x1200 60Hz
1920x1080 (1080p) 60Hz
1280x720 (720p) 60Hz

**Lower resolutions and refresh rates, not stated but below the maximum, may also be supported
Wide Screen Supported Yes
Audio Specifications 7.1 Surround Sound
Physical Characteristics Product Height 0.5 in [1.3 cm]
Product Length 3.8 in [97.0 mm]
Weight of Product 5.5 oz [156.0 g]
Product Width 2.8 in [70.0 mm]
Color Black
Power Power Source AC Adapter Included
Input Voltage 110V-240V AC
Input Current 0.3A
Output Voltage 12V DC
Output Current 1A
Center Tip Polarity Positive
Plug Type M
What's in the Box 1 - Included in Package HDMI over CAT6 Transmitter
HDMI over CAT6 Receiver
IR Blaster
IR Receiver
Quick-Start Guide
2 - Included in Package Universal Power Adapter (NA/JP, EU, UK, ANZ)



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Product Support

Talk to an Advisor

We are always ready to assist you with any questions you may have.

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Frequently Asked Questions


  1. The power adapter may not be connected at the correct unit or may not be connected at all.  Please check your product manual to see where your power adapter has to be positioned.
  2. An adapter to another video signal may be connected to the Transmitter or Receiver unit.  Please avoid any converters for the initial setup.
  3. The Cat 5 or 6 cable coming from the transmitter or receiver unit may be connected to a network switch.  Some of our video extenders will work in this configuration, but others will not. Please check your product manual to see if your model can be used connected to an IP network. For the initial setup, avoid connecting the Cat 5 or 6 cables to any network switch, hub, or router.
  4. The category of Unshielded Twisted Pair (UTP) cables may not meet StarTech.com’s requirements. Ensure at least Cat 5, 5e, or six cables are used, and they have eight wires. Some Cat 5 cables only have four wires. If using Cat 6 cables, be aware they have more twists per foot, so you may have to use shorter cable lengths if using Cat 6 cabling between your video extenders.
  5. Bundling up the UTP cabling connected to the extenders can cause crosstalk, which will prevent the video signal from showing on the display.  Unwrapping the cable should resolve this issue.
  1. Please check to see if your model has an adjustable Gain dial on the remote unit.
  2. If it does, use it to adjust the color until it is acceptable.
  3. Replace the VGA cable with a higher quality cable like StarTech.com’s MXT101MMHQ.

Compliance and safety

Compliance letters

Safety Measures

  • If product has an exposed circuit board, do not touch the product under power.
  • If Class 1 Laser Product. Laser radiation is present when the system is open.
  • Wiring terminations should not be made with the product and/or electric lines under power.
  • Product installation and/or mounting should be completed by a certified professional as per the local safety and building code guidelines.
  • Cables (including power and charging cables) should be placed and routed to avoid creating electric, tripping or safety hazards.
*Product appearance and specifications are subject to change without notice.

Customer Reviews

(1 reviews)
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1 - 1 of 1 Reviews
(3 Stars)

Small issues

By: silleeni - 10/25/2021
Plug and play install. Small issues. DTS-HD,Dolby plus,Dolby atmos bitstreaming does not work through this. Normal AC3 and dts bitstream works. PCM in 7.1 in 24bit and high khz works. 4k60Hz works. HDR works. I have CAT6a cable.
| Helpful?
Barrington, Customer Support on 10/26/2021 5:20:10 PM
We are sorry to hear that you experienced difficulty with ST121HD20V. One of our technical advisors will reach to gather information about your setup, and see if we can help resolve the issue you are seeing.
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