AN~PRC-74

Radio Set AN/PRC-74 or the AN/PRC- 74A is a lightweight, two-way communications set that is capable of receiving and transmitting voice and telegraph signals. Single-sideband (SSB) modulation is used for voice transmission, and continuous wave (CW) modulation is used for telegraph transmissions. The voice and telegraph receptions are demodulated and applied to a headset. The frequency range of the radio set for both receive and transmit modes of operation is between 2.0 mHz and 11.999 mHz for the A models and 2.0 - 17.999 mHz for the "B" version.

The radio set may be portably operated or operated at a fixed station. When portably operated, the radio set is powered by either a rechargeable nickel cadmium storage battery pack, or a dry cell battery pack. An external battery charger and power supply assemblies are provided with the radio set when used at a fixed station. The power supply assembly allows the radio set to be powered by either the alternating current (AC) or direct current (DC) voltages available at the operating site. The external battery charger assembly is used to recharge the radio set batteries prior to using the radio set portably.

Three types of antennas are supplied with the radio set. Operating in the low end of the high frequency spectrum, the range of the radio set may be extended to hundreds of miles with the proper selection of frequency and antenna type.

The operational features of the AN/PRC- 74 and AN/PRC-74A are identical except that the A model has been modified by MWO 11- 5820-590-35/1 to permit operation with the AN/GRA-71 coder burst equipment. Refer to TM 11-5820-590-12 for operational procedures for coder burst operation. Refer to paragraph 1-59 of the technical manual for circuit differences between the two models.

Images

These Images are from a complete wiring harness swap. The front audio section of a PRC-74 was hacked to pieces in a botched HAM conversion. I replaced the entire wiring harness of the radio with a donor PRC-74B after confirming every connection in the harnesses were the same.

Front of a severely hacked PRC-74
Front of a factory PRC-74B
Topside of the donor 74B
Bottom side of the donor 74B
Front panel of the 74
topside of the 74 before the swap
Read of the hacked 74, note the power connector
backside of the radio cover
Inside the front panel of the donor 74B
Harness removed from the donor ready to be installed
I replaced the harness from left to right, only removing parts as i was ready to connect the new harness.