The radio sets AN/VRC-12 and VRC-43 through VRC-49, commonly referred to as the AN/VRC-12-series, were the vehicular tactical radio communications equipment used extensively by combat units from the Vietnam War (1965) through the early 1990s. These VHF FM single channel radio sets replaced the AN/GRC-3 through GRC-8 series. They were fully compatible with the AN/PRC-25 and AN/PRC-77, the basic infantry battalion manportable radio extensively used in the 1960s through 1980s. The AN/VRC-12 equipment provided 920 VHF/FM voice channels in the 30-76 MHz range.
A soldier operates a Radio Set AN/VRC-12 (RT-524A/VRC Receiver-Transmitter) in the tactical operations center of the 32nd Separate Infantry Brigade (Mechanized), Wisconsin Army National Guard, during Exercise REFORGER '86, 22 January 1986.
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Radio Set AN/VRC-12, Vehicular Tactical Radio Sets (RT-246 Receiver-Transmitter).
From 1965 through about 1990, its period of service, U.S. Army and USMC units communicated with each other via these AN/VRC-12 tactical radios with few exceptions. The radio set was the Army and USMC tactical vehicular combat net radio, providing short range, two-way radio telephone communications. It was used primarily in utility vehicles, trucks, armored personnel carriers, Bradley Fighting Vehicles, self propelled Howitzers and the PATRIOT Missile System.
The AN/VRC-12 generation of radios was planned to be replaced in the mid-1980s by the SINCGARS family of VHF frequency-hopping radios with embedded cryptographic circuitry. However, a series of program setbacks repeatedly delayed this upgrade so that by 1990 only a few units had the SINCGARS while most continued to use the VRC-12s.
Radio Set AN/VRC-12 Components
Radio Set AN/VRC-12, Vehicular Tactical Radio Sets (RT-524 Receiver-Transmitter).
The AN/VRC-12 family consisted of various combinations of two basic components, a receiver-transmitter and an auxiliary receiver. It consists of three major units: Receiver-Transmitter RT-246A/VRC with a channel-presetting capability (10 pushbuttons), Manual Receiver-Transmitter RT-524A/VRC with built-in loudspeaker, and Auxiliary Receiver R-442A/VRC (wt. 18.5 lbs/8.4 kg). The radios also could be used with speech security or digital data equipment.
The two versions of receiver-transmitter were:
RT246A/VRC: could operate on one of ten frequencies preset by the operator, controlled by pushbuttons. The RT-246 was designed for use in tracked vehicles where the operator could not reach the control panel. (61 lbs/27.7 kg)
RT-524A/VRC: developed primarily for use in those vehicles where the operator could reach the control panel easily. The operator had to select each frequency manually on the RT-524, which had a built-in loudspeaker in the space occupied by push buttons on the RT-246. (wt. 58 lbs/26.3 kg)
Other components include the Frequency Selector Control C-2742/VRC (NSN-5895-00-892-3343) and the Intercommunication Set C-2299/VRC (NSN-5820-00-892-3340), control boxes for remote control of the radios when mounted beyond the reach of the operator.
The R-442 receiver was available for use when the primary requirement was to monitor radio traffic, not to participate. By using the R-442 another net can be covered to maintain contact and up to date status while the RT unit is used for tactical control and acknowledgement.
Many antenna options were available, including antenna AT-912/VRC or AT-1729/VRC, and an auxiliary antenna with base AB-15 or AB-558. Optional control boxes and an interphone amplifier were supplied if operation of the radio set was to be extended to crew members in heavy armored vehicles or crew-served weapons. Audio accessories, such as headsets, handsets, microphones and loudspeakers could be chosen from a wide variety of standard items available. In tanks, a headset-microphone combination (MK-1697) built into a DH-132 or DH-133 series of helmets were commonly used.
For vehicle installation, the MT-1029 shock protected mount was used (for the RT-524 or RT-246), along with the MT-1898 mount (for the R-442). Shock mountings were supplied as standard items for vehicular installation. The AM-2060 Audio Amplifier/Power Supply was installed on the MT-1029 Mount to provide DC power and interface to the VIC-1 Vehicle Inter-Communication system, if used.
Use of the AN/VRC-12 in Vietnam
In Vietnam this equipment was often removed from vehicles for use in bases such as forward tactical command posts. In most cases, major tactical units were issued the VRC-12 family of radios just before or shortly after their deployment to Vietnam during 1965 and 1966.
Since division and brigade commanders were frequently airborne, moving by helicopter from area to area, the main burden of command communications was on the FM radio nets. Commanders had their helicopters equipped with two AN/VRC-12 series radios. The division commander kept his on the division and brigade nets. He also needed to monitor the various maneuver battalion nets, so a further innovation was required. The command helicopter console was modified to take a third AN/VRC-12 with push-button tuning for preselected channels. Thus the commander's aide could very quickly give him a brigade net on the second radio or a maneuver battalion net on the third radio, or both.
Shortly before arriving in Vietnam in late 1966, the 4th Infantry Division received the new AN/VRC-12 series and the AN/PRC-25 radios. After arriving the division received the new KY-8 voice security equipment for use with the VRC-12 series. The AN/PRC-25 was a big improvement over the AN/PRC-10, providing increased range and eliminating calibration problems (later upgraded to the almost identical AN/PRC-77). The KY-8, on the other hand, although it provided complete voice security, also reduced the transmission range of the radios. Whenever a battalion of the division was deployed a great distance from the command post, an RC-292 antenna was usually erected. This antenna in conjunction with the AN/VRC-12 series and the KY-8 combination provided good, secure communications over all distances the division covered in its operations.
Manuals for the AN/VRC-12 Family of Radio Sets
The VRC-12 family of radio sets have manuals organized in two section, one for wheeled vehicles and one for tracked vehicles. This division reflects the differences in mounting, accessories and use in the two types of vehicles.
TM 11-5820-401-10-1 "Operators Manual Radio Sets VRC-12 thru VRC-49" (140 pages) is the operator's manual for wheeled vehicles where the interphone system is typcially not used. It contains information on major components RT-524, RT-246 and R-442 plus accessories including Mounts MT-1029 and MT-1898, Antenna AS-1729 and AT-912 as well as information on audio and security equipment.
TM 11-5820-401-10-2 is similar to the -1 volume but is the operator's manual for tracked vehicles where the interphone system is typically used. The AM-1780 and the components of the AN/VIC-1 vehicular intercom are covered in addition to the receiver-transmitter, receiver, power supply and other components covered in the -1 volume.
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