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Compact HDMI extender kit with USB-powered transmitter and rack-mountable receiver

STARTECH

STARTECH ST121HDBTDK 4K HDMI Extender 70m HDBaseT v extender

SKU CH-Q3GR-VK5W3 MPN ST121HDBTDK

Extend 4K HDMI up to 70 m or 1080p up to 230 m over a single CAT5e cable with a USB-powered transmitter and 7.1 audio support

  • Spec summaryHardware Audio: Yes Cabling: Cat 5e UTP or better Daisy-Chai
  • HighlightsExtend HDMI video over CAT5 or CAT6 cabling up to 230 ft awa
  • Product dimensions0.98 in × 2.68 in × 3.15 in
  • Product weight8.89 oz
  • Included items1 x HDBaseT transmitter 1 x HDBaseT receiver 1 x USB power c
  • Compact USB-powered transmitter simplifies discreet installation
  • Extends 4K UHD video up to 70 m over single Cat 5e cable
  • Maintains 4K quality at 40 m distance
  • Supports 7.1 surround sound for full audio fidelity
  • Includes mounting hardware for professional receiver setup

Compact 4K HDMI Extender Kit

This HDBaseT extender transmits HDMI video and 7.1 audio up to 70 m over a single Cat 5e or better cable. The transmitter draws power from a USB port on the source device and includes a built-in HDMI cable for a compact footprint. Mounting hardware for the receiver is supplied for a professional installation. Ideal for digital signage and remote display applications.

Suited for integrators needing long-distance 4K

The kit delivers UHD 4K at 40 m and 1080p at the full 70 m range, making it a fit for displays within those limits. It is not for buyers who require daisy-chaining multiple receivers or transmitting beyond 70 m. The single-cable design also means it cannot support installations that demand dual-cable redundancy.

HDBaseT range defines the use-case

At 40 m the extender maintains 4K UHD resolution, while 1080p and lower resolutions reach the full 70 m distance. This single specification determines whether the link length matches the required image quality.

How it compares

Measured against everything we stock in A/V Extenders & USB Hubs, at today’s prices. Recalculated every night.

Price $251.99
Pricier than about 76% of the 239 comparable items (median $132.99).

Specifications

Product
Brand nameStarTech.com
Model nameST121HDBTDK
Size & build
Product dimensions0.98 in × 2.68 in × 3.15 in
Product weight8.89 oz
Shipping weight1.13 kg
Package size254 × 203 × 152 mm
In the box
Included items1 x HDBaseT transmitter
1 x HDBaseT receiver
1 x USB power cable (transmitter) (1310 mm)
1 x universal power adapter (receiver) (NA / EU / UK / AU)
1 x mounting kit (receiver)
1 x screw kit for mounting
1 x footpad set (receiver)
1 x quick start guide

Questions about this item

Does the kit include both transmitter and receiver, or do I need to buy a cable separately?

The box contains one HDBaseT transmitter with a built-in HDMI cable, one receiver, a USB power cable for the transmitter, a universal power adapter for the receiver, mounting hardware and footpads. A Cat 5e UTP or better cable up to 70 m is required and sold separately.

When should I choose the 70 m reach versus the shorter 40 m figure?

The extender delivers 4K UHD resolution up to 40 m (130 ft). For 1080p or lower resolutions the signal reaches the full 70 m (230 ft) distance. Select based on the resolution you need at the far end.

What does the 4K claim mean when the unit is installed in a real setup?

At distances up to 40 m over a single Cat 5e or Cat 6 cable the extender passes UHD 4K video with 7.1 surround sound. Beyond 40 m it falls back to 1080p while still reaching 70 m.

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