Quick install guide
DE: Bedienungsanleitung - de.startech.com
FR: Guide de l'utilisateur - fr.startech.com
ES: Guía del usuario - es.startech.com
IT: Guida per l'uso - it.startech.com
NL: Gebruiksaanwijzing - nl.startech.com
PT: Guia do usuário - pt.startech.com
Manual Revision: 01/08/2016
For the latest information, technical specications, and support for 
this product, please visit www.startech.com/ST121USBHD.
Packaging contents
•  1 x HDMI over CAT6 transmitter 
•  1 x HDMI over CAT6 receiver 
•  2 x Ethernet cables 
•  2 x USB to Mini-USB cables 
•  1 x universal power adapter (NA/EU/UK/AU) 
•  1 x mounting kit 
•  1 x quick install guide 
System requirements
•  1 x HDMI® enabled video source device with cabling (i.e. computer, 
Blu-ray Player)
•  1 x HDMI enabled display with cabling (i.e. television, projector)
•  2 x available USB power source or AC electrical outlet at the 
location for the transmitter and receiver
•  (Optional) 4x USB peripheral devices
ST121USBHD
HDMI® over CAT6 extender with 4-port USB hub - up to 165 ft (50m)
*actual product may vary from photos
Preparing your site
1.  Determine where the local video source (i.e. computer, Blu-ray 
Player) will be located and set up the device.
2.  Determine where the remote display will be located and place or 
mount the display appropriately. 
Notes: Please ensure that the transmitter and receiver units are 
situated near an available AC electrical outlet or a USB power source.  
Make sure all devices are turned o before beginning installation.   
Hardware Installation
1.  Install Transmitter Unit 
a) Position the transmitter unit near the video source (i.e. 
Computer, Blu-ray Player). 
b) Connect an HDMI cable from the video source device (i.e. 
computer, Blu-ray Player) to the HDMI in port on the transmitter 
Unit. 
c)   If you’ve chosen to connect USB peripheral devices (Optional)
using the USB hub, please connect a USB to Mini-USB cable (not 
included) from the USB host connection port on the transmitter 
to an available USB port on your source device (i.e. computer). 
 
Note: All USB ports on this extender are USB 2.0 
 
Note: While two USB to Mini-USB cables are included, these are 
required to provide power to the extender and receiver. A third 
cable that is not included is required for console support. 
 
Product overview
Front view
Rear view
Transmitter Unit Receiver Unit
Transmitter Unit Receiver Unit
HDMI 
input
USB host 
connection 
(Mini-USB)
HDMI 
output
USB hub 
ports
power 
source 
(Mini-USB)
link out A (RJ-45 
Connector)
3. link out B
(RJ-45 Connector)
power 
source 
(Mini-USB)
3. link out B
(RJ-45 Connector)
link out A (RJ-45 
Connector)
USB hub ports