RJ Connector

Connectors are a vital component of electronic devices and systems, providing a secure and stable connection. RJ connectors are no different. These sockets are used to connect telecommunications equipment such as telephones, modems and computers. Why is this version called an RJ connector? RJ stands for registered jack. Today, the best known type of socket is RJ-45, which is used for computers and is mainly referred to as an Ethernet socket by the industry. Read more...

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How to choose the right RJ connector?

RJ sockets are part of a family of modular connectors that used to be developed for telephones, which is why they are sometimes referred to as telephone connectors. Today, landline telephone handsets still use 4P4C or RJ-9 versions to connect to the handset. But RJ-11 and 12 plugs are used for analogue telephones. These types of sockets are used to connect a conventional telephone to the telephone network. And the RJ-45 socket is used to connect computers.

What are the differences between the different types of RJ connectors?

One of the most important differences between the types of RJ sockets is the type of device they are used for, and the other difference is in their design. The RJ-11 has a 4/4 contact, the RJ-12 has a 6/6 contact, the RJ-45 has an 8/8 contact and the RJ50 has a 10/10 contact.

What cables should be used for RJ connectors?

The RJ-11 and 12 versions can be used to connect telephone cables, which can be flat, twisted or round. The telephone cable has 4 or 6 wires, which are colour coded. When choosing a telephone cable, care should be taken to ensure that it is shielded, particularly in areas with high levels of electromagnetic interference, so that the call quality is clear and sufficiently loud. In the world of mobile telephony, analogue telephones are used less and less. Therefore, of all the RJ connectors, the RJ-45 type is the most commonly used.

This plug can be connected to any cable from Cat5 and Cat6 to Cat7 and the new Cat8. Each cable is made up of 8 wires, or 4 twisted pairs of wires, which conforms to the 8P8C design of the RJ-45 standard. Each strand is protected by plastic insulation. The twisting of the pairs of wires with different thread pitches ensures noise suppression. However, they differ greatly in performance. These cables are often referred to as RJ-45 cables, but there is another name for them: UTP cables.

How to connect an RJ connector to an existing network or device?

There is a tab on the RJ plug that allows you to insert the plug into the device or network socket in only one way. This innovative solution prevents incorrect connection.

For a quality connection, what features should you look for when choosing RJ plugs?

These types of cables have adequate shielding, which means they protect the signal from electromagnetic and radio frequency interference. The connector design features a tab to ensure that the connector can only be plugged in one way. Built-in magnetic parts allow for overcurrent protection.

Thanks to these features, RJ connectors guarantee high reliability, which greatly protects the devices and equipment connected to them. In addition, RJ-45 connectors and cables are able to transmit power to the devices they are connected to, in addition to transmitting data by exploiting the unused twisted pair of wires. This is called Power over Ethernet (PoE) technology, which can transmit up to 15.4 W of power. But Poe++ can transmit up to 100 W.

What speeds do RJ connectors and cables support and how do they affect network performance?

It depends on what kind of cable is connected to the RJ socket. The Cat5 cable allows 100 Mb/s bandwidth and 100 MHz throughput. The Cat6 version allows 1,000 Mb/s bandwidth and 250 MHz throughput, but if you connect the Cat7 cable to the RJ-45 socket, this increases to 10,000 Mb/s bandwidth and 600 MHz throughput.


RJ jacks are available in a variety of sizes and shapes in DND Telecom Center's web store, including RJ-9, RJ-11, RJ-12 and RJ-45 plugs. RJ-11 and RJ-12 sockets are commonly used for telephones. Each type has specific characteristics that make it suitable for a particular application.