Belden 4855R 75-Ohm SDI Video Cable — Per Metre

Belden 4855R 75-Ohm SDI Video Cable — Per Metre

Belden 4855R is a miniature RG-59-type, 75-ohm coaxial video cable, sold here by the metre for installers and engineers who terminate their own SDI runs. Belden publishes it for ultra-high-definition digital video, including 4K single-link 12 Gb/s UHDTV, 4K D-Cinema, 8K quad-link UHDTV, and HD-SDI 1080p applications. Its construction pairs a 23 AWG solid silver-plated copper centre conductor with gas-injected foam polyethylene insulation and a dual shield of Duobond II foil tape and 95 percent tinned copper braid, all in a compact 0.159 in (4.04 mm) overall diameter under a PVC jacket.

Key features

• 75-ohm precision video coax, Mini RG-59 type
• 23 AWG solid silver-plated copper centre conductor
• Gas-injected foam polyethylene insulation
• Duobond II foil tape shield at 100 percent coverage
• Tinned copper braid shield at 95 percent coverage
• Overall diameter of just 0.159 in (4.04 mm)
• Belden-published application: 12 Gb/s single-link UHDTV and HD-SDI
• Sold per metre for route-based ordering

Why a miniature 12G cable exists

Modern broadcast and AV racks pack more signals into less space every year, and full-size coax becomes the limiting factor: thick cables fill trays, strain connector panels, and resist the tight bends that dense routers and patchbays demand. A Mini RG-59 design answers that problem by carrying the same 75-ohm digital video role in a 4.04 mm package, so more runs fit through the same containment and high-density panels stay manageable. The engineering that makes this possible is in the published construction: the silver-plated solid conductor supports high-frequency performance, the gas-injected foam dielectric keeps the cable light and dimensionally consistent, and the foil-plus-braid shield combination guards the signal in electrically busy equipment rooms. This is the cable class chosen for flypacks, OB trucks, and compact studio racks where space is genuinely scarce.

Planning a route honestly

A cable’s published application describes what the design is made for, not an unlimited-distance promise. The distance a 12G-SDI signal travels successfully depends on the complete path: the cable length, the connectors and how well they are terminated, any patch points in between, and the sending and receiving equipment. Plan the route from Belden’s attenuation guidance for this exact cable, keep the run as short as the installation allows, and treat every intermediate connector as part of the loss budget. Lower-rate signals travel further on the same cable, so a route that is marginal at 12G may be entirely comfortable at 3G or HD rates; the correct approach is always to verify the finished link at the format you actually intend to run.

Termination notes

Miniature coax needs connectors made for its exact dimensions. Choose 75-ohm BNC connectors whose manufacturer lists 4855R compatibility, and use that connector maker’s strip dimensions, crimp die, and procedure rather than judging fit by eye, because the centre conductor, dielectric diameter, and shield arrangement must all match the connector design. A bulk-cable order supplies the cable length ordered; connectors, tools, and a tested finished assembly are separate items to plan for. After termination, inspect the centre pin seating and shield capture, then test the link end to end at the working format before the route is closed up inside trunking or a rack.

Belden 4855R gives system builders a manufacturer-specified, miniature 75-ohm coax for high-density SDI work, with published construction and electrical design aimed at 12 Gb/s single-link video, ordered by the metre to suit the route.