SCR-194 / SCR-195 Radio

The SCR-194 and SCR-195 were developed by the U.S. Army Signal Corps Engineering Laboratories at Fort Monmouth, NJ, the first "walkie talkie" portable AM radios. They were fielded in 1938-39 and used widely by the U.S. and Allies during World War II, generally for batallion and company level links. The SCR-194/195 was replaced by the SCR-300 or SCR-536 in infantry and airborne units, and by the SCR-609/610 in artillery units. Although declared obsolete mid-1944, there were still many in service at that time.

SCR-194 / SCR-195 walkie talkie field radio.  Photo: Popular Science, August 1941
SCR-194 / SCR-195 "walkie talkie" field radio. Photo: Popular Science, August 1941.

Today in WW II: 11 Dec 1941 Germany and Italy declare war on the United States and US reciprocates.   

SCR-194 / SCR-195 Walkie Talkie Radio Description

SCR-195 consisting of BC-322 with accessories.  Photo:  Courtesy of Thomas Chial
SCR-195 consisting of BC-322 with accessories. Photo: Courtesy of Thomas Chial.

The SCR-194 and SCR-195 two-tube AM radio sets were nearly identical with differences in frequency band and headset/handset to meet the needs of Artillery and Infantry respectively:

  Radio Unit Frequency Antenna Headset/Handset
SCR-194 BC-222 28-52 MHz AN-29 HS-22, Microphone T-24
SCR-195 BC-322 52-65 MHz AN-30 Handset TS-11, Remote Control RM-14

The other characteristics of the radio sets were the same:

Modulation AM
Channel Spacing 400 kHz
No. Channels One
Frequency Control VFO
Tx Power 100 mW
Rx Sensitivity 10 uV
Weight 25.1 pounds
Case Metal, black wrinkle finish
Dimensions (WHD) 5.5 x 7.9 x 8.7 inch (140 x 200 x 220 mm)

SCR-195 with antenna fully extended. Photo: Popular Science, August 1941
SCR-195 with antenna fully extended. Photo: Popular Science, August 1941.

Other related equipment includes the canvas carrying bag/backpack (BG-71), leather saddlebags (BG-82) for horse cavalry, and a chest for spares. The power source is battery BA-32 and the two tubes are VT 33 and VT 67. The Technical Manual TM 11-238 describes both the SCR-194 and SCR-195.

Operating the SCR-194 and SCR-195 Radios

SCR-195 consisting of BC-322 with accessories, in BG-71 canvas carrier.  Photo:  Courtesy of Thomas Chial
SCR-195 consisting of BC-322 with accessories, in BG-71 canvas carrier. Photo: Courtesy of Thomas Chial.

The SCR-194 / SCR-195 transmitter and receiver are for voice communication only. This radio set is designed for point to point communication with a range of approximately 5 miles. (In the jungles of Guadalcanal, range was reported to be much less, one to two miles.) Although the set is not equipped for code communication, code may be whistled into the microphone under conditions where interference prevents clear reception of voice.

The radio set may be worn on the back of the operator and operated from this position. Carrying straps are provided which fit over the shoulders and allow free use of hands while the set is in operation. This radio may also be mounted and operated in a vehicle. For satisfactory performance, the ignition should be shielded and the vehicular antenna used. The standard antenna should not be used for vehicular operation. The vehicular antenna (Mast sections, MS 49, MS 50, MS 51, and mast base, MP 22) is designed, electrically and mechanically, for use in a vehicle and should be so used.

There are 62 channels for communication on the SCR 194/195, each separated from the next by 400 kilocycles. Before going into the field each unit is assigned one of these channels on which to work. There are two coils in the set, marked A and B respectively. Only one is to be used at any one time. When operating on channels 1-25, inclusive, use Coil A. When operating on channels 26-62, inclusive, use Coil B. When using Coil A, the antenna is completely extended. When using Coil B, the top two sections are dropped.

To operate, place the set on the ground, and plug in the headset, microphone or handset. Check to see that the proper coil (A or B) is in place. Extend the antenna to the length corresponding to the coil being used. Screw the antenna into the top of the lid of the radio set. Turn the filament toggle switch on, and turn the filament knob until you see whether or not you can get at least 2 1/2 volts reading on the meter. If you cannot get this voltage, the battery should be replaced. After getting satisfactory filament voltage, turn the filament knob back to 2 volts, then calibrate the set. After set is calibrated, switch back to assigned channel. Cut off calibrator switch. The set is now ready to operate.

To calibrate, turn the calibrator switch on. Turn channel dial to red mark nearest the assigned frequency. A hissing sound should be heard. Adjust calibrator knob until this sound has stopped, or it is at a minimum. Set is calibrated. Turn off calibrator switch and turn dial to assigned channel.

BC-322 dataplate, partially obscured by equipment web strap.  Photo:  Courtesy of Thomas Chial
BC-322 dataplate, partially obscured by equipment web strap. Photo: Courtesy of Thomas Chial.

Note on terminology: The SCR-536 was originally called the "Handie-Talkie" (meaning it could be carried in your hand) while the term "Walkie-Talkie" referred to man-portable backpack units like the SCR-194 / SCR-195 (meaning you could walk and talk). Gradually "walkie talkie" came to mean any small, handheld radio, including the SCR-536, usage that is not consistent with the WW II era usage.

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