The 1J37B / 1Zh37B / 1Ж37Б is a Soviet subminiature high-frequency pentode-mixer with two control grids, designed for mixing two voltages of different frequencies. Housed in a tiny glass envelope with flexible wire leads, this directly heated oxide-cathode tube operates in any position and is built for reliability in demanding environments. It is a New Old Stock (NOS) item, never used, and is sought after by restorers of vintage military and portable radio equipment, as well as by radio amateurs and experimenters working with compact, battery-powered valve designs.

Key Features & Specifications

• Type: Subminiature HF Pentode-Mixer (two control grids)
• Base: Flexible wire leads (no socket required)
• Filament Voltage: 1.2 V ±0.12 V
• Filament Current: 59 mA (tolerance ±7 mA)
• Anode Voltage: 45 V (nominal); 100 V maximum
• Grid 2 Voltage: 45 V (nominal); 60 V maximum
• Grid 1 Voltage: 0 V
• Anode Current: 2.55 mA
• Mutual Conductance (both grids tied): 1.25 mA/V; per grid: 0.63 mA/V
• Reverse Grid 1 Current: ≤ 0.1 µA
• Vibration Noise: ≤ 60 mV (at RA = 5 kΩ)
• Cathode Type: Oxide, directly heated
• Service Life: ≥ 5,000 hours
• Dimensions: 8.5 mm diameter × 42 mm length
• Weight: ≤ 4–4.5 g

Applications & Compatibility

• Primary Use: Frequency mixing (two signals of different frequencies), HF amplification, and oscillation in vintage subminiature radio receivers and military transceivers.
• Frequency Capability: Rated for operation up to 60 MHz.
• Mounting: Operates in any position; flexible leads allow direct soldering into compact circuits.

Condition

• Status: NOS (New Old Stock). Never used.
• Origin: Made in the USSR.

Why Choose This Tube?

The 1J37B / 1Ж37Б is a specialized subminiature pentode-mixer that embodies Soviet-era engineering for compact, reliable radio equipment. Its two control grids allow it to function as a frequency converter in a single envelope, simplifying the design of vintage receivers and test gear. With a guaranteed service life of at least 5,000 hours and the ability to operate in any position, it is a robust choice for restoration projects. For modern builders, it offers an authentic path to battery-powered regenerative receivers, small transmitters, or hybrid audio experiments where its low filament drain and classic “tube glow” are appreciated. As a readily available NOS component, it delivers both historical character and dependable performance at a modest cost.