HDMI over CAT6 Extender - 4K 60Hz - 330 ft. (100 m)

4K HDMI® Balun | Visually Lossless Compression | IR Support

Product ID: ST121HD20L

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  • Maintains astonishing picture quality up to 330 ft. (100 m) away, with support for UltraHD 4K over non-proprietary CAT6 cabling
  • Also supports HD 1080p video resolutions at distances up to 460 ft. (140 m)
  • Hassle-free, professional installation with included mounting brackets
Your price
€653.99 EUR excl. VAT
€791.33 EUR incl. VAT

This HDMI® over CAT6 extender lets you transmit your HDMI signal over a CAT6 cable up to 330 ft. (100 m) away. The extender supports Ultra HD 4K with support for 3D and the accompanying digital audio.

Long-Distance Transmission

Extend your HDMI signal to up to 330 ft. (100 m) with this HDMI over Ethernet extender. 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.

The extender also works to extend an infrared (IR) signal, enabling you to control your video source from the remote location.

Astonishing 4K Picture Quality

This HDMI Ethernet extender supports a 4K 60Hz (3840 x 2160) UHD resolution, providing four times the picture quality of high-definition (1080p), ensuring a crystal-clear picture that's ideal for displaying your 4K video content in office buildings, airports, retail settings and more.

Plus, because the extender supports 1080p and lower resolutions at up to 460 feet away, you can comfortably use this extender to make any video source look great.

Compatible with HDCP 2.2 Devices

Connect your HDMI 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.

ST121HD20L is backed by 2-year StarTech.com warranty with free lifetime technical support.


  • Extend your 4K HDMI signal in offices, building lobbies, shopping centers, airports and more
  • Optimize placement of your demo stations at tradeshows and in auditoriums
  • Use existing CAT6 infrastructure to create digital signage

Partner Numbers

  • Ingram Micro España V934872
  • Esprinet ST121HD20L
  • UPC 065030882637


  • OS Independent logo


Warranty Information Warranty 2 Years
Connector(s) 1 - Connector A HDMI (19 pin)
3.5 mm Mini-Jack (3 Position)
3.5 mm Mini-Jack (3 Position)
3.5 mm Mini-Jack (3 Position)
1 - Connector B RJ-45
HDMI (19 pin)
3.5 mm Mini-Jack (3 Position)
3.5 mm Mini-Jack (3 Position)
3.5 mm Mini-Jack (3 Position)
Environmental Operating Temperature -5°C to 40°C (23°F to 104°F)
Storage Temperature -15°C to 55°C (5°F to 131°F)
Humidity 0% - 95 % RH (No Condensation)
Hardware AV Input HDMI
AV Output HDMI
Cabling Cat 6 UTP
Audio Yes
Chipset ID Norelsys NS 5730, NS5731
Indicators 2 - LED Indicators Power LED
Link LED
Packaging Information Package Height 9,5 cm [3,7 in]
Package Length 24,5 cm [9,6 in]
Shipping (Package) Weight 1,5 kg [3,2 lb]
Package Width 20,0 cm [7,9 in]
Performance Max Distance 140 m / 460 ft
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 Color Black
Product Height 26,0 mm [1,0 in]
Product Length 11,0 cm [4,3 in]
Weight of Product 537,0 g [19,0 oz]
Product Width 75,0 mm [3,0 in]
Material Steel
Power Power Source 2 AC Adapters Included
Input Voltage 110V-240V AC
Output Voltage 5V DC
Output Current 3 A
Center Tip Polarity Positive
Plug Type M
What's in the Box 1 - Included in Package HDMI Transmitter
HDMI Receiver
CAT6 Cable
IR Kit
Quick-Start Guide
2 - Included in Package Universal Power Adapters (NA/JP, EU, UK, ANZ)
3.5 mm to DB-9 RS-232 Adapters
4 - Included in Package Mounting Brackets


Your price
€14.99 EUR excl. VAT
€18.14 EUR incl. VAT
Your price
€37.99 EUR excl. VAT
€45.97 EUR incl. VAT
Your price
€55.99 EUR excl. VAT
€67.75 EUR incl. VAT

DC Power Adapter - 5V, 3A

Replace your lost or failed power adapter

Your price
€21.99 EUR excl. VAT
€26.61 EUR incl. VAT


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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.

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