Rare New Old Stock (NOS), Never-In-Box (NIB) U52 full-wave rectifier valves from Marconi, manufactured in Italy during the 1930s. These are among the most sought-after power rectifiers of the pre-war era, featuring the iconic **“fat Coke bottle” glass envelope**, **black anode plates**, and **foil getter at the bottom**.

The U52 was designed as a high-performance upgrade for the 5U4, 5U4G, CV575, CV1071, and VU71 series — offering superior current handling, lower internal resistance, and exceptional stability under heavy load. Its robust construction made it ideal for military, broadcast, and early hi-fi amplifiers requiring clean, high-current DC supply.

Key features:

• Ultra-rare “fat Coke bottle” ST-shaped glass envelope
• Long, smooth black anode plate for efficient heat dissipation
• Foil getter at the bottom — signature of 1930s Marconi production
• Original black phenolic base
• Made in Italy under Marconi’s strict quality control

Each unit is individually tested for emission, voltage regulation, and endurance over original datasheet specifications. Due to their age, scarcity, and legendary performance, these tubes are highly prized by restorers of vintage equipment and builders of premium tube amplifiers.

Available as matched pairs or matched quads upon request, with full documentation and provenance.

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