Grass Valley Group 8-Slot Rack 903 903P Distribution Amplifier 900 Power Supply

Grass Valley Group 8-Slot Rack 903 903P Distribution Amplifier 900 Power Supply

This Grass Valley Group 8-slot rackmount chassis comes populated with two differential input clamping distribution amplifiers — one Model 903 and one Model 903P — along with a Model 900 Dual Power Supply module. Five of the eight card slots are empty, providing room for expansion. The chassis accepts Grass Valley Group 900-series plug-in modules and connects via BNC and multi-pin circular (Amphenol-style) connectors on the rear panel.

Specifications & What's Included

• Chassis: Grass Valley Group 8-slot rackmount frame (approx. 3U)
• Module 1: Grass Valley Group Model 903P — Differential Input Clamping Distribution Amplifier
• Module 2: Grass Valley Group Model 903 — Differential Input Clamping Distribution Amplifier
• Module 3: Grass Valley Group Model 900 — Dual Power Supply, 1/2A fused
• Empty slots: 5 of 8 slots unpopulated
• Front panel controls (per amplifier): INT/OFF/EXT toggle switch, GAIN adjust, CLAMP adjust, INPUT jack, DC control
• Front panel (per amplifier): 4 OUTPUT jacks (labeled 1–4)
• Front panel (Model 900): FUSE cap, 1/2A rated, dual binding post outputs, DC banana jacks
• Rear panel: dense BNC connector array — PULSE IN, OUTPUT channels 1–4, INPUT channels 6–7 labeled
• Rear panel: Amphenol-style multi-pin circular power/signal connector
• Form factor: Rackmount
• Country of manufacture: United States

Applications

The Grass Valley Group 900 series was a modular broadcast video signal distribution platform widely used in professional television production facilities, broadcast master control rooms, and post-production suites from the 1970s through the 1980s. The Model 903 and 903P are differential input clamping distribution amplifiers designed to accept a composite video signal, clamp its DC level, and distribute it to multiple outputs simultaneously — a fundamental function in any broadcast routing environment where signal integrity and proper black-level reference are critical. The differential input design allows these amplifiers to reject common-mode noise and hum picked up on cable runs, making them suitable for long-haul facility cabling. The Model 900 Dual Power Supply provides regulated DC rails to the plug-in modules within the chassis. This type of modular card-frame architecture was a hallmark of professional broadcast infrastructure of the era, allowing facilities to mix distribution amplifiers, sync generators, proc amps, and other signal processing modules in a single chassis. These units are still sought after by broadcast engineers maintaining legacy analog video facilities, archivists, and collectors of vintage professional video equipment.