The R-311 “Omega” (Р-311 «Омега») is a Soviet-era shortwave radio receiver designed for military use. It was manufactured from 1954 until the mid-1970s, playing a crucial role in various branches of the Soviet armed forces and other Warsaw Pact nations.

History

The R-311 receiver was developed in 1949 at the design bureau of the Aleksandrovsky radio factory. The development project was led by V. M. Khakharev and M. E. Movshovich, using the R-253 “Alfa” (Р-253 «Альфа») receiver as a basis for the design. Serial production began in 1954, and the receiver was adopted by the Soviet military in 1956.

Deployment

Ground Forces

In ground operations, the R-311 was used in conjunction with various mobile radio complexes, such as:

• R-102
• R-118
• R-140
• R-820M
• Command-staff vehicles BMP-1KSh and BTR-60PU

Air Force

The Air Force equipped their mobile ground stations with the R-311, specifically models:

• R-839
• R-843

Navy

The Navy installed the R-311 on board their ships, extending its use to maritime operations.

International Use

The receiver was also supplied to other Warsaw Pact countries and exported to nations like Vietnam, China, and Cuba.

Production and Post-Military Use

At least 60,000 units of the R-311 were produced. Following their service life, these receivers were handed over to DOSAAF organizations and later found a niche among radio amateurs.

Technical Specifications

The R-311 “Omega” is a superheterodyne receiver with one frequency conversion. The technical details include:

• Circuitry: Composed of eight identical 2Ж27Л pentodes.
• Signal Reception: Designed to receive telegraphic and telephone (AM) signals.
• Intermediate Frequency (IF): 465 kHz
• IF Filter: Quartz with adjustable bandwidth.
• Calibrator: Integrated quartz calibrator.
• Antenna: Adapted for Kulikov’s type.
• Output: Supports two pairs of low-resistance headphones and a 1500-ohm wireline.

Frequency Bands

The receiver’s frequency range is divided into five sub-bands:

1. 1.0 – 1.88 MHz
2. 1.88 – 3.30 MHz
3. 3.30 – 5.58 MHz
4. 5.58 – 9.20 MHz
5. 9.20 – 15.0 MHz

Sensitivity

• Telegraph Mode: Not worse than 3 μV for a signal-to-noise ratio of 3:1 and voltage on headphones of 1.5 V.
• Telephone Mode: Not worse than 7.5 μV.

IF Passband

Adjustable from 0.3 to 4 kHz.

Power Supply Options

• Battery 2KN-24 and vibration transducer VP-3M2 (continuous operation not less than 12 hours).
• Battery 2KN-24 and anode battery BAS-80 (continuous operation not less than 24 hours).
• AC Mains 127 or 220 V through rectifier ВС-3.

Operating Conditions

• Temperature Range: -40 to +50 °C.
• Humidity: Up to 98% relative humidity.

Dimensions and Weight

• Receiver Dimensions: 445 × 285 × 220 mm.
• Receiver Weight: 21 kg.
• Complete Set Weight: Not more than 38 kg (including accessories and spare parts).

Interesting Features

• Uniform Valves: All valves in the receiver are the same, preventing damage from rearrangement and simplifying spare parts inventory.
• Low Power Consumption: Uses directly heated filament valves, consuming about 4 W, comparable to similar transistor radios.
• SSB Reception Modification: While not initially designed for single-sideband modulation, the R-311 can be modified to receive such signals.

References

1. Belgrade, Djole. “RADISTA – Download”. www.radista.info. 
2. “R-311”. www.greenradio.de. 

Bibliography

V. I. Shapkin, The Red Ears, Soviet professional tube radio receivers from 1945-1970. Aviko Press, 2003. (Published in Russian)