HDMI over Dual CAT5 Extender - HDMI Bus-Powered - 1080p

HDMI over CAT5 with IR Extension | 7.1 Audio Support | 30 m (100 ft.)

Product ID: ST121SHD30

3 stars (8 reviews) |
  • Hassle-free setup and no power adapter required with an extender kit that’s powered using the HDMI bus
  • Easily control your video source from a remote location with IR remote control extension
  • Crystal-clear picture quality with support for resolutions up to 1080p HD
Your price
€89.99 EUR excl. VAT
€109.79 EUR incl. VAT
Where to buy
Temporarily in short supply, see alternative item
HDMI Over CAT5e/CAT6 Extender with Power Over Cable - 165 ft (50m)
HDMI Over CAT5e/CAT6 Extender - 165 ft
Extend HDMI® up to 165ft (50m) over Cat5e/6 cabling with Power over Cable to Receiver

This HDMI® over dual CAT5 extender transmits your HDMI A/V signal with IR to a remote location up to 30 m (100 ft.) away over dual CAT5/CAT6 cables.

Simplify Your Setup with No Power Adapters Required

Unlike most 1080p HDMI extenders that can require up to two power adapters, this HDMI over CAT5 extender is powered using the HDMI bus and does not require external power. Power-free installation makes your digital-signage solution simple. Mounting hardware is built into both the transmitter and receiver to ensure a discreet, professional installation.

Control Your Video Source from the Remote Display

With IR extension built-in this HDMI transmitter and receiver kit offers remote infrared extension, enabling you to control your video source from the remote display, ensuring you can always see what you’re doing, even from a distance.

Crystal-clear 1080p Video

This HDMI extender maintains your 1080p picture quality, ensuring your remote picture is crystal clear. The extender also supports 7.1 audio for optimum sound quality. Support for HD video and 7.1 channel audio lets you create brilliant digital signage solutions that capture the attention of your audience.

The ST121SHD30 is backed by a 2-year StarTech.com warranty and free lifetime technical support.


  • Distribute HDMI in large buildings such as commercial shopping centers, stadiums, schools, and hospitals
  • Extend your HDMI audio/video signals to locations where power outlets are limited such as industrial sites
  • Integrators and system designers can use existing CAT5 or CAT6 infrastructure to create digital-signage solutions

The StarTech.com Advantage

  • Cost-effective HDMI extension through non-proprietary network cabling
  • Clean, professional installation, with built in mounting hardware, and no power adapters required

Partner Numbers

  • Ingram Micro Italy V932886
  • Esprinet Italy ST121SHD30
  • Tech Data - Italy 4428689
  • UPC 065030851718


Warranty Information Warranty 2 Years
Connector(s) 1 - Local Unit Connectors HDMI (19 pin)
2 - Local Unit Connectors RJ-45
2 - Remote Unit Connectors RJ-45
1 - Remote Unit Connectors HDMI (19 pin)
Environmental Operating Temperature 0°C to 40°C (32°F to 104°F)
Storage Temperature -10°C to 60°C (14°F to 115°F)
Humidity 0% - 80 %
Hardware Ports 1
Cabling Cat 5 UTP or better
Daisy-Chain No
Indicators 1 - LED Indicators Input
Packaging Information Package Height 5.5 cm [2.2 in]
Package Length 21.0 cm [8.3 in]
Shipping (Package) Weight 408.0 g [14.4 oz]
Package Width 15.0 cm [5.9 in]
Performance Max Distance 30 m / 100 ft
Maximum Digital Resolutions 1080p / 1920x1080
Wide Screen Supported Yes
General Specifications IR dongle frequency - 35 to 56 khz
Physical Characteristics Weight of Product 241.0 g [8.5 oz]
Color Black
Material Aluminum
Product Length 8.2 cm [3.2 in]
Product Width 4.5 cm [1.8 in]
Product Height 2.2 cm [0.9 in]
Special Notes / Requirements Note The extender does not work through Ethernet equipment, such as switches or routers
This extender requires two CAT5 cables for the entire distance of your cable run.
ST121SHD30 draws power from the HDMI source device, as a result a limited number of devices may not be capable of powering the unit, such as the Mac Mini or Samsung Chromebooks.
What's in the Box 1 - Included in Package HDMI over CAT5e/6 UTP Transmitter
HDMI over CAT5e/6 UTP Receiver
IR Extender Kit
Mounting brackets
User Manual
4 - Included in Package Foot Pad Set



6 ft HDMI to DVI-D Cable - M/M

Connect an HDMI®-enabled output device to a DVI-D display, or a DVI-D output device to an HDMI-capable display

Your price
€11.99 EUR excl. VAT
€14.63 EUR incl. VAT


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Frequently Asked Questions


There are a few things you'll want to take care of before you deploy your new video extender in your setup.

It’s important to make sure you have everything you will need ahead of time. These items are listed below.

  • Transmitter
  • Receiver
  • Video source
  • Display
  • Video cables
  • (Optional) Ethernet or fiber cables
  • (Optional) Power adapter(s)

It’s also important to test everything in a simplified setup ahead of time to make sure everything works and that you understand how it works. 

In order to set up your video extender, complete the following:

  1. Position your video transmitter near your video source.
  2. Connect the video output from your video source to the video transmitter.
  3. (Optional) Connect the power adapter to the video transmitter.

Note: Not all video extenders require external power, or require external power on both ends.  Refer to the manual for more information.

  1. Position your video receiver near your display.
  2. Connect the video output from your video receiver to your display.
  3. (Optional) Connect the power adapter to the video receiver.
  4. If using a wired video extender, connect your network cabling between the video transmitter and the video receiver.
  5. (Optional) If you are extending anything else supported by your video extender connect those devices to the transmitter and receiver.
  6. (Optional) If you are using a wireless extender, there may be a sync button you need to press to pair the transmitter and receiver.

Now that you have set up your video extender, you can check that everything is working.  You should be able to see your video source's output on the display connected to the video receiver.

If at this point you have further questions regarding a Startech.com video extender, contact our technical support team for further assistance. 

To get the highest quality signal from your source to your display when you use an HDMI extender, do the following:

  • Make sure that the HDMI versions of the source, extender, and destination are compatible. For example, if you require 3D support, make sure that all of the devices can support 3D over HDMI.

  • Use the least amount of adapters, splitters, or converters as possible. Each device that you use in your setup creates additional points of potential failure and creates more steps for an HDCP key to hop through, which may cause issues with older displays. For more information on HDCP, refer to the following FAQ: http://www.startech.com/faq/video_signal_converters_HDCP.

  • Use an HDMI extender that exceeds the requirements of the setup. For example, if you need to extend the signal 200 feet, it is best to use an extender capable of more than 200 feet.

  • Make sure that all of the CAT 5/6 runs are as straight as possible, with the least amount of coiling.

  • Make sure that all of the patches, wall jacks, and cables use the highest possible CAT specification, (for example, CAT 6), and were tested to conform to the standard.

  • Use patches, wall jacks, and cables with the same pin configuration. For more information on T568A versus T568B wiring, refer to the following FAQ: http://www.startech.com/faq/network_cables_a_vs_b_pinout.

  • Keep the cabling away from sources of high noise.

  • Make sure that you use adequate electrical grounding in your setup.


  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.

When you troubleshoot issues with a video extender, there are some quick tests that you can complete to rule out potential problems. You can test to make sure that the following components are working correctly and are not the source of the issue:

  • Video and Ethernet cables

  • Video extender

  • Video source (such as a DVD player or computer)

  • Video destination (such as a monitor or projector)

Note: When you are testing setup components, you should avoid using video adapters. For example, if you are converting a VGA source to HDMI for use with an HDMI extender, you should use an HDMI source when you test the components.

To test your setup components, try the following:

  • Use the cable, video extender, video source, and video destination in another setup to see if the problem is with the components or the setup.

  • Use a different cable, video extender, video source, and video destination in your setup to see if the problem persists. Ideally, you should test a component that you know works in another setup.

When you test your cables, it is recommended that you do the following:

  • Test each cable individually.

  • Use short cables when you are testing.

When you test the video source and video destination, it is recommended that you do the following:

  • Remove the video extender from your setup and test to make sure that the video source and video destination work together without the video extender.

  • Test to make sure that the video source and video destination work together at the resolution that you want to use.

Note: In order for your setup to work properly, the video source, extender, and destination all need to support the resolution that you are using.

Before You Buy

You should only use video converters and extenders if it is absolutely necessary to do so. In many cases, most video converters and extenders are not necessary if you purchase the correct cable.

The following table lists the maximum length of cable for common video standards.

Video standard Maximum length
DisplayPort 50 ft. (15.2m)
HDMI 50 ft. (15.2m)
DVI 50 ft. (15.2m)
VGA 200 ft. (71m)

Note: StarTech.com offers cables longer than what is listed above, including active cables, which typically include built-in active signal boosters that allow for longer cables. Active cables are specifically designed to exceed the suggested maximum lengths and are tested at the listed specifications (for example, the maximum listed resolution).

Video adapters

Video adapters passively adapt a cable from one connector type to another. Video adapters do not change the signal type, or change the video standard.

Examples of common applications for adapters include the following:

  • DVI-I to VGA

  • RCA to BNC

  • Mini DisplayPort to DisplayPort

  • Couplers (female to female, or male to male)

Note: You can use a coupler to extend a cable for a short distance. However, each coupler that you use can introduce signal loss, which degrades the signal quality.

Video converters

Video converters actively process and change the signal type from one video standard and convert it to another standard. They are typically used to convert digital to analog and vice versa, but can be used to convert a digital signal to another digital video standard (for example, HDMI to DisplayPort).

Video converters work over short distances from the source to the destination: up to 15 feet or 3 meters.

Video extenders

Video extenders convert an input signal to a higher voltage for transmission over longer distances and then convert the input signal back to the original video standard. The input and the output signal will match on a video extender, as the same video standard is maintained end-to-end. If a cable is extended with adapters or converters, the signal quality degrades.

Note: For more information on using a video adapter or converter with a video extender, see the following FAQ: http://www.startech.com/faq/video_signal_converters_convert_then_extend.

If you need to use a video extender with a video adapter or converter, you should position the adapter or converter as close to the video source as possible. For example, if you need to take a VGA signal from a computer and send it 200 feet to an HDMI® projector, you should convert the signal from VGA to HDMI and use an HDMI extender.

Note: For more information on when to use cables or extenders, see the following FAQ: http://www.startech.com/faq/video_signal_converters_when_to_convert.

Yes, this video extender works with set-top boxes, provided the set-top box meets the following requirements:

  • The set-top box must be High-bandwidth Digital Content Protection (HDCP) compliant.
  • The set-top box must support devices being connected between the video source and display. If the set-top box requires a direct cable connection between the video source and display, it won't work with this video extender.

No, this device is designed to be a point-to-point solution using networking cabling only. 

This device outputs HDMI video signals. If you have a display or video destination that uses another type of video connection, there are ways that you can convert the video signal or connection. These options are outlined below and organized by the target connection.


When you consider whether to convert an HDMI video signal to another connection type, it is important to know if the media that is being converted from the HDMI video connection is protected by High-bandwidth Digital Content Protection (HDCP). If the media is protected by HDCP, you cannot convert to analog video connections because they do not support HDCP. You may experience this issue when you use devices like Blu-ray players, DVD players, and certain gaming consoles.

Target connection Conversion
VGA HDMI to VGA: https://www.startech.com/AV/Converters/Video/?filter_AVINPUT=HDMI&filter_AVOUTPUT=VGA.

HDMI to DVI: https://www.startech.com/Cables/Audio-Video/HDMI/HDMI-to-DVI/.

DisplayPort HDMI to DisplayPort: https://www.startech.com/AV/Converters/Video/?filter_AVINPUT=HDMI&filter_AVOUTPUT=DisplayPort.


This device has an HDMI input port.  If you have a video source that uses another video connection, there are options available to convert the video signal or connection. These options will be outlined below for each video source connection.

Source Connection



VGA to HDMI: https://www.startech.com/AV/Converters/Video/?filter_AVINPUT=VGA&filter_AVOUTPUT=HDMI.


DVI to HDMI video converters: https://www.startech.com/Cables/Audio-Video/Video-Adapter/HDMI-Cable-Adapters/.

DVI to HDMI video cables: https://www.startech.com/Cables/Audio-Video/HDMI/HDMI-to-DVI/.


DisplayPort to HDMI passive converters: https://www.startech.com/AV/Displayport-Converters/DP-HDMI/?filter_CONVERTTYPE=Passive.

DisplayPort to HDMI active converters: https://www.startech.com/AV/Displayport-Converters/DP-HDMI/?filter_CONVERTTYPE=Active.

DisplayPort Passive and Active Conversions

The converter that you require depends on the type of DisplayPort video source that you are using. For more information about converting DisplayPort video signals, refer to the following FAQ: https://www.startech.com/faq/DisplayPort_Converter_DP_Multi_Mode.

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

(8 reviews)
3 out of 5 stars
  • 5 (3)
  • 4 (1)
  • 3 (0)
  • 2 (1)
  • 1 (3)
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1 - 8 of 8 Reviews
(5 Stars)
By: jamesmedia - 10/31/2014
| Helpful?
(1 Stars)

It wouldn't work over a 50 foot Cat6 cable.

By: Fred - 10/05/2015
It wouldn't work over 50 foot of Cat6 cable. So we went down to fry's and bought a different style and it worked fine.
| Helpful?
Customer Support, Customer Support on 10/8/2015 1:49:24 PM
Hello Fred, Thank you for taking the time to review our ST121SHD30 HDMI Extender. We are sorry to hear the extension was not working over the 50ft CAT6 cable and we would like to offer some help. With this model of extender it supports up to a maximum of 100ft of CAT5e or CAT6 cabling. Was the extender tested using two cables? It does require that two cables be used for the extension and both cables must be the same length. If two cables were used, are you able to try the extender in a “test bench” setup using two short Ethernet cables? Another potential issue is that not all HDMI video sources are able to provide the power required by this extender. A few examples are phones that use MHL adapters, and some models of cable or satellite box. If the video source used may be one that is unable to provide the required power we would recommend our ST121SHD50 model which comes with an external power supply. Please note the ST121SHD50 does not support any IR extension functionality. Here is our ST121SHD50: http://www.startech.com/AV/Extenders/HDMI/HDMI-over-Cat5-Cat6-Extender~ST121SHD50 For more troubleshooting steps, please refer to this article which can be found on the support page for the ST121SHD30: http://www.startech.com/faq/video_extenders_general#ST121SHD30 We are always here to help with our free lifetime technical support. If this did not resolve your issue, please get in touch with us and reference case #332-289136 so we can further assist you. You can also reply here and we will be sure to follow up. Thank You, Customer Support StarTech.com http://www.startech.com/support
(5 Stars)
By: Nick42 - 08/26/2016
It just works, when connected correctly. 1080p over 2 Cat-5e cables can be spotty (it drops out from time to time), but using dual Cat-6 works flawlessly. Just remember that port1 to port1, and port2 to port2. Getting them crossed will not work. The IR plugs work perfectly. And for the record: The runs were 78', direct from box to box.
| Helpful?
(2 Stars)

This product only works partially as advertised

By: AndersL - 03/09/2017
This product only works partially. The transfer of picture and sound over LAN works as advertised. The IR extender feature of this product however only works partially, and with some major drawbacks. Constantly when trying to use the IR extender feature, the transfer of the hdmi signal breaks and the LED light on the reciever unit dies, a few seconds later the LED lights up again and the picture returns. Over time when you use this IR extender feature theres a high chance of losing hdmi signal on the reciever unit, and this interruption of picture and sound renders this feature useless.
| Helpful?
(1 Stars)

Doesnt work

By: LithiumKid1976 - 12/19/2017
bought it, spent a day testing it. tried everything. it failed miserably.
| Helpful?
Sam, Customer Service on 12/22/2017 11:53:56 AM
Thank you for sharing your review of our ST121SHD30. I apologize for the issues you've had with setting it up! Please ensure that you are using 2 Ethernet cables between the transmitter and receiver as this unit will not function properly with only 1 cable. This extender is covered by a 2 year warranty and free lifetime technical support. Our Technical Advisors are available 24 hours a day, 5 days a week, to provide support. For further troubleshooting, I recommend reaching out to us at 1-800 265-1844 or www.startech.com/chat Sam, StarTech.com Support
(1 Stars)

Will not work at 20m

By: LRO333 - 01/19/2018
System simply refuses to work at my required distance of 20m. I've bench tested the equipment using 2m cables and it worked fine, but when connected to the 20m cables, there was no video transmission at all. I also tested the transmission over CAT5e and CAT6, but useless.
| Helpful?
Sam, Customer Service on 1/24/2018 11:43:30 AM
Thank you for your review of ST121SHD30. We apologize that it isn't working as desired yet. Are you using 2 Ethernet cables between the transmitter and extender at 20m? Both are required for operation. Please be sure that your cables are a direct connection between the transmitter and receiver. Equipment such as switches and routers will cause the traffic to not pass properly. Keystone jacks and patch panels can introduce more possible points of failure as well. Please also know that we have Technical Support Advisors available 24 hours a day, 5 days a week, to provide support. If you have any further problems, feel free to reach out to us using one of the contact links at the bottom of https://www.startech.com/support
(5 Stars)

HDMI Extender

By: Starr - 01/06/2019
Great product. Simple to configure. Low Cost. Work with CAT5e or 6. Great resolution. I like the screw down tabs for use in industrial situations.
| Helpful?
(4 Stars)

Quality extenders work quick and built to last

By: NickD_CA59 - 01/20/2019
I have been using this HDMI extender for a while now and it has been working well as intended. The extenders come in come in a box about the size of a box of cookies. In the box are the two extenders (sending side and receiving side) which are a little more narrow that a pack of cards, as well as two IR cables (sending side and receiving side). No power is required to use the extenders as they appear to receive power from the HDMI cable. Both ends of the extender are the same size, made of metal and with matching ports. Once all of the cables are connected properly the extender starts working in 1-2 seconds. You need to connect BOTH ethernet cables and BOTH HDMI cables for the extenders to start working. None of the cables need to match, as I tested with 1x 50ft ethernet, 1x 1ft ethernet, 1x 15ft HDMI & 1x 10ft directional HDMI cable at the same time with everything working. The only time I was able to made the extender not work is when I tried to use with 4k (there is nothing on the box that indicates it is only 1080p). The extenders work very well and quickly. I received this product in exchange for an unbiased review.
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