What Is 75 Ohm Coax Cable? | Video, RF And Hardline Explained

A 75 ohm coax cable is a coaxial cable built with a nominal 75 Ω characteristic impedance, the standard used for video, RF, and broadband signal transmission.

Characteristic impedance isn’t resistance you can measure with a multimeter on a spool of cable. It’s a property set by the ratio of the center conductor’s diameter to the dielectric’s diameter, and that single geometric number decides whether your signal arrives intact or bounces back down the line as reflected energy. Pick the wrong impedance for the system you’re feeding, and the loss shows up as ghosting, weak signal, or a return-loss figure that fails spec — not as anything obviously “broken.”

Here’s what 75 ohm coax actually is, how it differs from the 50 ohm cable sitting next to it on the shelf, and the specs that matter once impedance is settled.

Why 75 Ohms And Not Some Other Number?

The value comes from a compromise between two competing needs: lowest possible signal loss, and highest possible power handling. Those two peaks sit at different impedances, and 75 Ω lands near the low-loss end — which is exactly what video and broadband systems care about most.

Attenuation, not power delivery, is usually the limiting factor over the distances video and RF signals travel. That’s why broadcast, CATV, and baseband video standardized on 75 Ω, while two-way radio, test gear, and most antenna feeds standardized on 50 Ω, where power handling and connector geometry win out.

Both are coax. Both have a center conductor, a dielectric, a shield, and a jacket. The impedance is the spec that separates their applications, not their basic anatomy.

What Do Real 75 Ohm Coax Specs Look Like?

Nominal impedance is the headline number, but the datasheet around it is what actually predicts field performance. Product sheets routinely publish impedance tolerance, capacitance, velocity of propagation, shielding coverage, and attenuation tables — and two cables both labeled “75 ohm” can behave very differently over 100 feet.

Canare’s 75 ohm coax product range is described as low-loss video and RF cable for broadcast and professional use, and Belden’s URM202 is a 75 Ω coax listed for video and RF signal transmission. Gore publishes a 75 Ω coaxial datasheet aimed at aerospace and high-frequency signal paths, which is where the impedance tolerance spec starts to matter in a way it doesn’t for a short patch run.

The aerospace standard EN 4604-005:2015 defines a 75 Ω cable (type WL) for aircraft electrical systems, operating from −55 °C to 200 °C up to 3 GHz, with 75 ± 5 Ω impedance, ≤ 60 pF/m capacitance, and 500 V RMS maximum operating voltage. That standard also pins mechanical limits: a 15 mm static and 25 mm dynamic minimum bend radius, roughly 2.35 mm maximum outer diameter, and about 12.5 g/m mass. For everyday installs, 75 ± 2 Ω and 75 ± 3 Ω tolerances turn up across hardline and series 6 families, with capacitance trending around 55–67 pF/m and velocity of propagation between roughly 66% and 85% depending on the dielectric construction.

What Is 75 Ohm Coax Used For, And What Breaks It?

The short answer: anything designed around 75 Ω impedance — video and RF signal paths, broadcast and cable-style hardline, and aerospace signal transmission up to 3 GHz. What breaks it is treating coax as interchangeable because the connector fits.

That’s the most common mistake, and it’s an expensive one. Two cables wearing the same BNC or F-type connector can carry completely different impedance tolerances, attenuation curves, shielding percentages, and diameters. Selecting by connector alone tells you nothing about whether the cable will hold up over the run length and frequency band you’re actually using.

The second mistake is ignoring frequency and length loss. Hardline and cable datasheets publish attenuation versus frequency tables for a reason — a cable that looks fine at low frequency can eat a meaningful chunk of signal at the top of its rated band. Length compounds it, so a short jumper and a 200-foot run are different engineering problems even with identical cable. For readers who want to compare specific models side by side before buying, our tested roundup of 75 ohm coax cable lays out the options and where each one fits.

There’s also a safety angle worth respecting on aerospace and industrial cable. Standards like EN 4604-005:2015 specify temperature, voltage, flammability, and bend-radius limits, and generic coax datasheets from Gore cover similar territory. Installing inside those environmental and mechanical limits — not assuming generic coax ratings apply — is what keeps a high-frequency run reliable.

And one compatibility caveat that trips people up: 75 Ω cable is meant for systems designed around 75 Ω impedance. Nothing in the referenced product data claims compatibility with 50 Ω RF systems, and the cable families here are explicitly described for video, RF, broadcast, or broadband use. Mixing them invites mismatch loss and reflections rather than a clean connection.

Frequently Asked Questions

Does A 75 Ohm Cable Fit A 50 Ohm Connector?

Often it physically will, and that’s the trap. BNC and F-type connectors show up on both impedance families, so a fit tells you nothing about electrical compatibility. Using 75 Ω cable in a 50 Ω system creates mismatch and reflections. Match impedance first, then choose the connector that belongs to that system.

Is Thicker 75 Ohm Coax Always Better?

Not automatically. Larger diameter usually means lower loss over distance, but it also means a stiffer cable with a bigger bend radius. The Gore aerospace datasheet lists roughly 2.35 mm outer diameter with a 15 mm static minimum bend radius — those mechanical limits matter as much as the electrical ones in tight installs.

What Actually Determines A 75 Ohm Cable’s Quality?

Impedance tolerance, attenuation at your working frequency, shielding coverage, capacitance, and velocity of propagation. Belden sheets list braid coverage values from 57% to 85%, and those return-loss and impedance-regularity specs tell you far more about real performance than the “75 ohm” label alone.