Original Siemens AZ12 Rectifier Tube – Tested
The Siemens AZ12 rectifier tube is a high-quality electronic component designed for industrial and consumer applications, serving as a vital part of the power supply stage in large-format vintage radio receivers and classic tube preamplifiers. Designed as a directly heated full-wave rectifier, its primary function is to convert alternating current (AC) into clean, stable direct current (DC) to power the rest of the electronic circuit.
Unlike its smaller counterpart, the AZ11, the AZ12 was designed to handle higher current demands, making it the standard rectifier for larger vintage receivers and other equipment with multiple amplification stages and greater power consumption.
Product Condition & Authenticity
This tube is an authentic vintage original. Although it is not supplied with its original factory box, it has been carefully inspected and electrically tested to verify filament continuity and basic rectifier operation. The tests confirm that the filament is intact and that the tube is free of internal shorts, ensuring it is ready for installation in your restoration project.
The Siemens & Halske Legacy
The Siemens name represents the highest standards of mid-20th-century German electronic engineering. Tubes manufactured or marketed by Siemens & Halske are renowned for their tight manufacturing tolerances, robust plate construction for efficient heat dissipation, and exceptionally high-quality vacuum. These features provide reliable, low-noise rectification and outstanding long-term durability, making Siemens tubes highly valued by restorers, collectors, and vintage electronics enthusiasts.
Who Is This Tube For?
Specialized technicians restoring Golden Age vintage radios, including classic models from Telefunken, Saba, Siemens, Grundig, and other European manufacturers.
DIY tube amplifier builders looking for tested NOS or vintage components for traditional vacuum tube power supply designs.
Primary Applications
Used in the power supply stages of large superheterodyne radio receivers, vintage console radios, and European analog test equipment designed for Y8A side-contact rectifier tubes.
Detailed Technical Specifications (Datasheet)
Tube Type: Directly Heated Full-Wave Vacuum Rectifier.
Cathode Type: Directly Heated.
Base (Socket): Y8A (8-pin side-contact base / Stahlröhrensockel).
Filament Voltage (Vf): 4.0 V AC.
Filament Current (If): 2.0 A to 2.2 A
(Critical technical note: Requires nearly twice the filament current of an AZ11.)Maximum Anode Voltage (Va max): 2 × 500 V RMS.
Maximum Output Current (Iout max): 125 mA.
A 2x 300V: Máx. 200 mA.
A 2x 500V: Máx. 120 mA.
Maximum Filter Capacitor Value: 60 µF.
Minimum Series Limiting Resistance (per Anode): 100 Ω (at 300 V RMS) / 300 Ω (at 500 V RMS).
(FAQ)
Can I use this AZ12 as a direct replacement for an AZ11?
Although both tubes physically fit the same Y8A socket and have matching pin configurations, caution is required. The AZ12 requires 2.0 A of filament current, while the AZ11 requires only 1.1 A. If the radio’s power transformer was not designed to handle this additional current demand, it may overheat or become damaged.
Always consult your equipment’s schematic and verify the transformer’s filament supply rating before installing an AZ12 as a replacement for an AZ11.
What is the condition of the tube?
This is an original vintage tube, supplied without its original box. It has undergone electrical bench testing to verify filament continuity and rule out internal shorts, ensuring it is ready for use.
What type of socket does it use?
It uses the Y8A socket, commonly known as the German side-contact base (Stahlröhren). It is not compatible with American octal sockets (such as the 5Y3) or European pin-type bases (such as the AZ1).
