Dear reader, are you constantly puzzled when faced with the soup of BNC connectors found in just about every professional video studio? Do you wonder why there are different types and which one you should use? Read on for a plain-language explanation of what makes BNC connectors tick and when to use each variety.
Overview: How BNC Connections Work
BNC connectors are used whenever we need to transmit high frequency signals from one device to another – like video cameras to video switchers in a TV studio. They maintain a constant impedance and secure connection to cleanly carry signals up to about 6 GHz.
At their simplest, BNC connections have two parts – a male connector and female receiver. The male inserts into the female and then locks by twisting a sleeve. This is known as a "bayonet" style connector.
But there are important differences between 50 ohm BNC and 75 ohm BNC connectors. These have to do with the spacing between the inner metal contact and outer ground sheath. Let‘s compare them below.
50 Ohm vs. 75 Ohm BNC Connectors
| Parameter | 50 Ohm BNC | 75 Ohm BNC |
|---|---|---|
| Impedance | Designed for 50 ohm cables | Designed for 75 ohm cables |
| Frequency Response | Widder bandwidth, up to ~4 GHz | Narrower bandwidth, up to ~2 GHz |
| Common Cables Used | RG-58, RG-142 | RG-59, RG-6, RG-11 |
| Typical Applications | Test equipment, ham radio, CCTV, data transmission | Video, Cable TV, satellite |
As shown in the table, 50 ohm BNC is engineered to match cables with 50 ohm characteristic impedance. This gives it a wider usable frequency range beyond 4 GHz. But 75 ohm BNC is tailored to work only up to about 2 GHz, in return providing better signal integrity when mating with 75 ohm coaxial cables commonly used in video settings.
Now let‘s go deeper on the history and use-cases for each type.
50 Ohm BNC
50 ohm BNC connectors have a precision impedance match to cables like RG-58 and RG-142. This gives them low loss across a wide frequency band – enabling uses beyond video to applications like aerospace, scientific instrumentation, and data networking.
For example, RG-58 coaxial cable paired with BNC connectors is what allows you to connect a radio antenna to a ham radio transmitter or scanner device. And every Ethernet T1/E1 WAN extender uses 50 ohm BNC connectors to receive data streams up to 2.3 Gbit/s.
So next time you need to ensure smooth signal transmission way up into the GHz range, choose a 50 ohm BNC connector.
75 Ohm BNC
The 75 ohm BNC connector was designed specifically to match widely-used 75 ohm video coax cables. This includes RG-59, RG-6, and RG-11 cables regularly deployed to carry video across studios or Cable TV networks.
By providing a precision 75 ohm connection, this BNC variant maximizes signal integrity for bleeding-edge Ultra HD or 8K footage – minimizing loss and distortion. It also results in the familiar BNC connectors populating the back of TV cameras, switchers, and other studio gear as standard.
For these reasons, 75 ohm BNC reigns supreme as the connector-of-choice when handling any professional or commercial video application under 2 GHz.
Miniature Variants – Tiny Footprints, Big Features
Beyond the common 50 or 75 ohm BNC connectors, you may also encounter "Mini" or "High Density" (HD) BNC used in specialty video production equipment. These miniaturized variants were developed by Amphenol to pack more connections into ever-shrinking camera and broadcast devices.
For example, HD-BNC allows 4x more ports than standard BNC in the same space – crucial when routing the numerous signals required in cutting-edge 4K and 8K camera setups. It also provides advanced 75 ohm precision across an ultra-wide bandwidth for tomorrow‘s formats.
However Mini BNC and HD-BNC can only connect to identical matches of themselves. So beware that while adapters between traditional BNC exist, they may introduce artifacts in high-resolution digital video. When implementing bleeding-edge studio gear, be prepared to fully commit to one connector size throughout.
Installing BNC Connectors
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