Are BNC connectors still used for anything?

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Have you been doing home theater and A/V installations for a while? If so, you might remember the BNC connector that was used for component connections in the 2000s and before. It has been used for SD video and HD video, but it’s rarely seen in consumer electronics today. Is it dead?

A quick look at the BNC connector

First let’s talk about the BNC connector. The Bayonet-style Neill-Concelman connector was patented in the 1950s as a combination of the N(Neill) and C(Concelman) connector styles. While N-connectors are still around, the C connector is no longer used. The goal was to have a connector for TV use that connected easily but stayed connected, and to have a metal sheath over the center conductor (unlike the F connector that uses the center conductor as a point of contact.) This would make for cables that could be connected and disconnected easily but didn’t fall out. The center sheath would guarantee that the cable wasn’t damaged by repeated connections.

To call the BNC connector a success is an understatement. It took over the world of commercial broadcasting, replacing RCA connectors and UHF connectors in broadcast equipment. For a time it was even used for computer networks. Yet, today the BNC connector is used only for very specific tasks and isn’t often seen outside broadcast facilities.

It’s important to realize that at the time of its release, the BNC connector was seen as wonderfully compact. It was considerably smaller than any other connector except the F connector. It was more durable AND easier to attach than an F connector. This led to its widespread use, in both 50-ohm and 75-ohm installations. It’s one of the few connectors that can commonly be found on both kinds of cables.

Why don’t you see this connector in use today?

There’s a simple reason that we rarely see BNC connectors today. The design of the connector allows RF to “leak out” or “leak in” if the cable is used to carry a signal at a frequency higher than 2GHz. This means right away that satellite TV is out of the question and even some cable systems use those frequencies. Computer data needs to use those frequencies as well if the data rate exceeds 100Mbps. So, it really can’t be used in the most common video distribution scenario.

The BNC connector is still used for SDI video, but your average consumer won’t ever see SDI. SDI is a high-definition, video-only connection that sends uncompressed video over a coaxial cable. This video is totally unencrypted, and it’s the highest possible quality. However, due to agreements with content providers, consumer-grade equipment won’t ever have SDI connections. If it did, people could make pristine digital copies of things, and that’s the content companies’ worst nightmare.

Today, you’ll generally see HDMI and nothing else. HDMI was designed from the start to be friendly to both consumers and content companies. It’s compact, easy to connect, and carries encryption that means you can’t just use it for digital copies. At least that’s the standard line. The truth is that HDMI encryption just isn’t that easy to defeat, but if you want to know how you’ll need to look elsewhere. This isn’t that kind of blog.

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About the Author

Stuart Sweet
Stuart Sweet is the editor-in-chief of The Solid Signal Blog and a "master plumber" at Signal Group, LLC. He is the author of over 10,000 articles and longform tutorials including many posted here. Reach him by clicking on "Contact the Editor" at the bottom of this page.