Inhaltsverzeichnis
Radio Receiver & Transmitter BC-222
Part of the SCR-194 radio system, manufactured for the United States Army Signal Corps.
Technical data
- Principle: transceiver, manpack
- Frequency range: VHF 27.7 - 52.2 MHz (channel spacing 400 kHz)
- Frequency memory: none
- Sensitivity AM approx. 10 μV
- Transmitter output: 100 mW
Power supply
- Rechargeable battery / battery operation: Heater and anode battery BA-32 (heater voltage 3 V, anode voltage 144 V, grid voltage 13.5 V, microphone voltage 4.5 V).
Dimensions
- 140 x 200 x 220 mm
Accessories
- Microphone T-24-E and headphones HS-22-B
- Antenna AN-29-B (exactly this version, the AN-29-C belongs to the BC-659)
- Battery BA-32
- Canvas bag BG-71
- Chest CH-33 with spare parts
- Box BX-13, a flat metal box that can be connected to the bottom of the set instead of a battery; external power sources or batteries can be connected via the cable.
- Remote Control Unit RC-66
- Additional material for vehicle operation RC-67, including antenna kit with a mast base MP-22 and mast sections MS-49, MS-50 and MS-51
Operation
The BC-222 / SCR-194 is a very early compact infantry manpack radio, which was developed by the U.S. Army Signal Corps around 1938. The AM transceiver operates in the VHF range 27.7 - 52.2 MHz and can be operated in two bandranges using two coils.
For portable operation, the radio was carried in a canvas bag, the AN-29-B antenna is screwed to the antenna base on top of the set, the matching BA-32 battery is attached to the bottom of the radio with two straps, the T-24-E microphone and the HS-22-B headset were usually used with the set; the TS-11-E handset was standard to be used with the SCR-195.
The front of the set can be protected with a metal cover, with the circuit diagram inside.
The upper part of the front panel is dominated by the dial, the lines are at a channel spacing of 400 kHz. The „CHANNEL“ tuning has a fine tuning drive. On the right is the regulator for the tube heater voltage, which must be set to exactly 2 V, the voltage is indicated on the instrument. The headset or microphone and headphones are plugged into a multi-pole socket below.
Each set is equipped with an individual calibration crystal, the calibration marks are marked in red on the dial. The crystals must not be exchanged between sets. For calibration, the set is tuned to the next upper calibration mark; if the „Calibrator“ crystal calibrator is switched on, the receiver background noise should become quieter when the red line is turned, otherwise it can be retuned using the metal knurled knob.
The AN-29-B antenna is screwed onto the insulated base on top of the set.
After loosening the two latches, the cover of the very simple set can be opened. The antenna connection is mechanically disconnected when the cover is opened. Inside are the two tubes VT-33 and VT-67. The BC-222 has a second antenna coil on a numbered ceramic carrier in two holders on the left inside of the cabinet.
With coil set A (coil C-174), the set operates in the 27.7 - 38.5 MHz range and the entire antenna length of twelve elements is used. With coil B (Coil C-175), the set operates in the frequency range 36.9 - 52.2 MHz and only the lowest ten antenna elements are extended.
Technical principle
In transmit mode, the VT-67 works as a Hartley oscillator, the VT-33 as a modulator tube. In receive mode, the VT-67 works as a receive detector in a super regenerative circuit (audion) and the VT-33 as an audio amplifier tube.
Tube layout
Technical documentation
Development
The set was developed at the Signal Corps Laboratories, Fort Monmouth and built by various companies as contractors.
It was used for communication within an artillery battalion.
