General Information on U.S. Portable Radios

The Beginning Steps in Ground Force Portable Radios, Pre W.W.II-Charts 1 and 7
The style developed in the beginning ( battery on the bottom, rigid antenna on the top, front panel controls ) was employed for the SCR-194 and SCR-195 for the Army and the TBY for the Navy. These were not really hand held devices, but were intended for backpack use even though they were not built like the backpacks with which we are familiar today These early units belong in chart two, but that one is crowded, so I unfortunately had to put them in charts 1 and 7 as there was more room there.

BC-611 / SCR-536

The VHF Squad Radio, W.W.II to Present-Charts 1 and 7 The first units developed that more or less conform to our present day expectations for handheld devices were the SCR-511 and the SCR-536. The SCR-511/BC-745 was designed to be used while riding a horse. However, the cavalry was abolished at the beginning of WW II, so it would seem it was a bit awkward to use on foot. It was, however, a marvellous example of good applied engineering, i.e. how to design a radio that was operable with just one hand while riding. However, the honour must go to the SCR-536/BC-611 ( along with the SCR-585/BC-721 glider version ) for being the first true handheld radio. ( Both units were made, in the beginning, by Galvin Mfg. Co, which is now Motorola. ) Packing a walloping 36 mw of Tx power, and subject to all the interference the HF AM band musters, it was still more or less a success. The Navy's MAB and DAV were also fairly small units that operated in the same AM frequency band, but not quite handheld.

PRC-6

The Korean War vintage PRC-6 ( although there is some debate as to whether it made it through development in time to actually see wartime service ), making use of the relatively new sub-miniature ( pencil sized ) tubes, improved greatly on the SCR-536. A VHF unit with 250-mw output, the FM mode of this unit reduced the interfering noise level greatly. After a long and drawn out research effort ( basically waiting for transistor and integrated circuit technology to develop ), the PRC-68 was produced, a very neat little package indeed. There had been an interim stop at the PRR-9/PRT-4, the first all solid state implementation, but they never really saw much use. The PRC-68 was to prove to be the father of five additional designs, the 68A, 68B, 126, 128, and 136 ( although this might prove to be a 128 high band only unit ).

PRC-68

The 1" longer PRC-68A followed, which was one of the first microprocessor-controlled units. It allowed random frequency programming, but you had to stay within one of the four sub-bands. The present unit, the PRC-68B ( V ) ( Marines ) / PRC-126 ( Army ) is a PRC-68A with a frequency display and external frequency settability. They are microprocessor controlled and allow more latitude in channel placement than even the PRC-68A because they have an external antenna tuning control.

SCR-300 / BC1000

The VHF Backpack Radio, W.W.II to Present-Charts 2 and 7 By all accounts, the first true backpack, the SCR-300, was a very successful design. It was followed by the Korean War vintage ( although they may have just missed actual war service ) PRC-8, 9, and 10 ( Armour, Artillery, and Infantry respectively ). Using sub-miniature tubes, these offered wider frequency coverage than before. The PRC-25 was the first synthesised unit, offered wider yet frequency coverage, and had just one tube ( RF power output stage ). Over 125,000 were produced. The all solid state but otherwise identical PRC-77 followed, with a large quantity produced as well. Tone squelch was introduced during this period ( i.e. PRC-25 and later ).

PRC-25

PRC-25

The current unit is the PRC-119 SINCGARS ( SINgle Channel Ground and Air Radio System ). It has an ability to FH ( Frequency Hop ) in order to avoid jamming. In addition, the "A" model is called ICOM ( Internal COMsec ). Comsec stands for COMmunications SECurity, i.e. voice scrambling in order to prevent intelligent interception of message content by the opposition. This model also sports a much longer battery life.

Meanwhile, there is an improvement program underway that has developed and purchased a small number of trial radios. The following was taken from the Web SIP ( SINCGARS Improvement Program ) Portable information.

"The Single Channel Ground and Airborne Radio System ( SINCGARS ) SIP ( SINCGARS Improvement Program ) Compatible Portable Radio, the RT-1753( C )/U, is a compact portable version of the SINCGARS SIP radio. This portable radio will be used along with the Lightweight Internet Controller ( LINC ) and Dismounted Soldier Unit ( DSSU ) in TF XXI ( Task Force XXI ) to support dismounted soldier operations and is designed to operate from a dismounted soldier's vest pouch. The radio replaces the current manpack version of the SINCGARS radio. The portable radio includes all SIP performance enhancements to include additional data mode features, embedded COMSEC, an external RS-232 Data Interface and packet switching for access into the tactical Internet. The radio weighs no more than 5 pounds ( with battery and antenna ), is approximately 1.9 inches by 10.6 inches in size ( with battery ) and provides selectable output RF transmit power up to two ( 2 ) watts and communication range of 3 to 4 kilometers. The portable radio uses a rechargeable NiCad battery pack. Battery life is approximately 6 hours. The portable radio shall consist of a portable radio, an antenna, and battery pack."

There are a number of instances where the portable RT ( Receiver/Transmitter ) unit forms the basis of a number of nomenclature systems ( i.e. AN/PRC, AN/VRC, AN/GRC, etc. ). The RT unit can, for instance, be attached to a vehicular mount that allows it to run on vehicle supplied power. Usually there is also an associated vehicular mounted amplifier that boosts the transmitter power, and boosts audio power as well in order to drive a speaker. Some of these systems even have a "jerk-and-run" capability, i.e. a quick way to disconnect and turn the RT into a portable again.

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