Mixed Brands 12BY7A New Old Stock Vacuum Tubes Sleeve of 5

Mixed Brands 12BY7A New Old Stock Vacuum Tubes Sleeve of 5 ( 4 Westinghouse, 1 RCA )

The 12BY7A is a miniature sharp-cutoff power pentode vacuum tube, optimized for high-frequency amplification with low plate voltage requirements and high output capabilities. It's less common in modern audio circles compared to triodes like the 12AX7 but remains valued in vintage TV restoration, ham radio equipment, and niche audio applications for its efficiency and bandwidth. The "A" variant (introduced in the mid-1950s) improved upon the original 12BY7 with better stability and reduced hum, making it electrically interchangeable but preferable in sensitive circuits.HistoryDeveloped during the boom in black-and-white television post-WWII, the 12BY7 series addressed the need for compact, high-power video amplifiers in receiver sets. The predecessor, 12BY7, debuted around 1951, but the 12BY7A was refined and released by General Electric in June 1955 as a more reliable option for demodulating and boosting video signals. Produced by major U.S. manufacturers like RCA, Sylvania, Westinghouse, and GE through the 1960s–1970s, it powered horizontal output and video stages in consoles from brands like Zenith and RCA. European equivalent is the EL180. Production tapered off with the transistor revolution in the 1970s, but NOS stock persists. Today, it's a collector's item for tube enthusiasts restoring 1950s–1960s TVs or experimenting with hybrid amps.Key Specifications

• Type: Sharp-cutoff power pentode (single section).
• Base: 9-pin miniature noval (B9A).
• Heater: Series: 12.6V at 150mA; Parallel: 6.3V at 300mA (unipotential cathode).
• Plate Voltage (Max): 250V (designed for low-voltage operation).
• Plate Dissipation: 6.5W.
• Amplification Factor: Medium-low gain (typically Gm 3,000–5,000 micromhos).
• Frequency Response: Up to 30–50 MHz, ideal for video bandwidth.
• Typical Applications: High-output video amplification where large swings are needed without high B+ supplies. Rugged construction with controlled warm-up time minimizes shock in series-heater TV strings.

Common Uses

• Television Receivers: Primary role as video output amplifier or sync separator in 1950s–1960s sets, handling wideband signals for sharp pictures.
• Ham Radio and RF: IF amplifiers or drivers in transmitters/receivers due to its bandwidth.
• Audio (Niche): Power stages in guitar amps, hi-fi, or DIY projects for clean, high-headroom drive—less harmonic distortion than triodes but brighter tone. Occasionally substituted in horizontal deflection circuits. Not as versatile as triodes, so it's rarely the "heart" of an amp but excels where power and speed matter.

 This Sleeve of  tubes are new old stock, Tested, and guaranteed full emission.

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