Developed by the Signal Corps Laboratories, Fort Monmouth, New Jersey; manufactured for the U.S. Signal Corps by various manufacturers.

The BC-312 receiver was built under licence for the US Signal Corps by various manufacturers during the Second World War and was used as a tabletop receiver in various radio stations.
In the Swiss Army, the receiver was used in the SE-402 / SM 46 radio station, which was in fact an American SCR-499/A acquired as a surplus.

• Principle: single conversion superhet, IF 470 kHz
• Operation modes: A1 with BFO, AM (A3)
• Frequency range: 1.5 - 18 MHz (1500 - 3000 / 3000 - 5000 / 5000 - 8000 / 8000 - 11000 / 11000 - 14000 / 14000 - 18000 kHz)
• Frequency display: Analogue dial
• Frequency memory: none
• Signal strength indicator: none
• Signal processing: Antenna tuning, AGC
• Features:
• Sensitivity: AM (A3) / Selectivity: kHz (-6/-60 dB)

• Batteries: 12 V DC from vehicle electrical system, DM-21 dynamotor to generate the plate voltages.

• 460 x 230 x 240 mm, weight 22 kg

The BC-312 receiver has a sturdy metal cabinet, measures 46 x 23 x 24 cm and weighs 22 kg.

The BC-312 is designed to be powered by 12 - 14 V direct current from a vehicle battery; the anode high voltage is generated by a „dynamotor“, a rotating converter.

The BC-312 was often used as part of the SCR-499/A shortwave radio station, which was intended for remote operation. At the remote operating site, the signals were received with the BC-312 and the signal was transmitted to the transmitter via a field telephone line. A second receiver, the mains-powered BC-342, which is technically very similar to the BC-312, is used at the transmitter site.

The frequency dial is located in the centre of the front panel. A mechanical aperture only opens to the part of the rotating frequency dial that corresponds to the selected frequency band range.

The band range switch is located on the left below the dial window, the coarse tuning knob „FAST TUNING“ on the right below the dial. The fine tuning knob „VERNIER“, which is mechanically linked to the tuning and has a locking function, is located diagonally above it.

In the bottom right-hand corner of the front panel is the connector for the signals from the SCR-499/A radio station, the main switch, which is combined with the manual (M.V.C.) and automatic (A.V.C.) HF gain control, and the transmit/receive switch.

The volume control, the BFO switch for receiving CW and single sideband transmissions and the BFO pitch control are all located in the upper right corner of the front panel; the dial illumination control is located to the right and the antenna tuning control to the left of the dial window.

There is a coaxial and a long-wire aerial socket in the top left-hand corner of the front panel and a terminal for an earth lead in the bottom left-hand corner of the receiver front panel.

To operate the receiver, it must be connected to the correct operating voltage; the aerial and the earth wire are connected to the corresponding terminals. The operating switch should be set to RECEIVE and the main switch to A.V.C, whereupon the humming of the rotary converter should be audible.

Use the band switch to select the 5000-8000 kHz range, then use the main tuning knob to search for the „Deutsche Welle“ signal from Cologne near the 6.075 MHz mark. The signal can then also be tuned to maximum using the fine tuning „VERNIER“. The volume control is used to adjust the volume, the BFO switch „C.W. OSC“ should be in the OFF position, the BFO is only activated to receive CW or SSB transmissions, such as those often heard in the amateur radio bands.

At first glance, the controls appear somewhat randomly distributed on the front panel, but the receiver, which was built in 1936, already has numerous features that can be found unchanged in later general coverage receivers up to the 1960s and 1970s - in 1936, less emphasis was placed on ergonomics and design aspects when developing a receiver.

The BC-312 is a stable and reliable receiver, but it is not uncommon for problems to occur with the rotating converter, which works in a similar way to an electric motor with a coupled alternator - these mechanically moving components are the most susceptible to faults, which is why the sets were often later converted to mains operation by radio amateurs.

single conversion superhet

The set is equipped with tubes: 6C5, 6C5, 6F6, 6K7, 6K7, 6K7, 6K7, 6L7, 6R7

• Radio Receiver BC-312 on the website of www.radiomuseum.org