U.S. Military Portable Radios

By Alan D. Tasker, WA1NYR

Table of Contents

Rebuttal

by Dennis Starks

In any work such as this, there is a tendency to pigeonhole items in an attempt to organize and simplify. This, plus the fact that one is always working with incomplete information, may lead to some inaccuracies. If you find something with which you do not agree or if you have something to add, please contact me.

If you are unfamiliar with military nomenclature, you might want to visit references 6 and 12 first.

Pictures for many of these radios appear in various web sites, and these are so indicated in the "Sources" section.

General Goals

· Lower Power Consumption
· Smaller Size/Lighter Weight
· Wider Frequency Coverage
· Closer Channel Spacing
· Synthesized Frequency Operation
· Higher Reliability

In more recent years, additional goals have been imposed.

· Internal Comsec (ICOM)
· Data send/receive capability along with voice

In addition, there has sometimes been at least a perceived need to develop radios that operate within more than one band (i.e. the AN/PRC-70, 113, 117D, 128, 138, 139, and the AN/URC-100 series). These radios help "interoperability" with other fighting force elements, as well as communications with local elements when they exist.

The Simple Six

· Tactical
1. The Squad Radio, VHF FM (wide band), a small hand held unit for very local communications within ground forces.
2. The main ground force communications device, a VHF FM (wide band) backpack, for longer distance communications than the squad radio can provide.
3. A FAC (Forward Air Controller) radio, generally a backpack, UHF, AM, for communications with aircraft.
4. A Special Forces radio, HF, SSB, backpack/manpack, for longer distance communications than would be provided by the VHF Backpack.

· Non-Tactical
5. SAR (Search and Rescue) radios, originally on 140.58 MHz, then 121.5/243 MHz, then 243 MHz only, and then multi channel, all AM, for downed airmen or other rescue duties.
6. Guard Duty/Fire Rescue/Other Use types, generally Low band (30-50 MHz) or High Band (152-174 MHz), or UHF (450-470 or 512 MHz), and/or the closely associated Government frequencies, narrow band FM.

The Charts

Recent Trends, Program Management Lead

· The Army has been the Lead in the Squad radio, although the Navy/Marines have contributed heavily.
· The Army is also the Lead in the VHF backpack area.
· The Air Force has traditionally been the Lead in the UHF FAC area with the Navy and Army tending to use what was developed. The notable exception is the PRC-75, which was developed for the Marines only. Additionally, there is little evidence to suggest that the Army has had a need for a UHF FAC radio later in time than the PRC-41 era.
· The Army generally Leads the effort in HF radio development.
· The Air force is currently the Lead in SAR system development.
· The Air Force is the Lead in the Scope Shield program, which is essentially non-tactical, although the Army has the PRC-127 project.

The Beginning Steps in Ground Force Portable Radios, Pre WWII-Charts 1 and 7

Chart 1 - Ground Force Portable Radios

The VHF Squad Radio, WWII to Present-Charts 1 and 7

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 6 additional designs, the 68A, 68B(V), 68B(V)2, 126, 128, and 136.

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 basically a PRC-68A with a frequency display. In addition, the PRC-126 has external frequency setability. They are microprocessor controlled and allow more latitude in channel placement than even the PRC-68A because they have an external antenna tuning control.

The VHF Backpack Radio, WWII to Present-Charts 2 and 7

Chart 2 - VHF Backpack

The PRC-25 was the first synthesized 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 time period.

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 WWW (reference 18).

"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 nomenclatured 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.

In a similar vein, there is an older concept where communication devices that have a primary application (mounted in a vehicle perhaps) have also a "Secondary Application" as a manpack (larger than a backpack) portable, or visa versa. These devices, when attached to the correct backpack frame, and when connected to the correct battery box with the correct cables, became portable. The following is a list of these types. There may be others.

· TBX, 2-5.8 MHz
· SCR-284/BC-654, tunable, 3.8-5.8 MHz AM, replaced by
· SCR-694/BC-1306, tunable, 3.8-6.5 MHz, replaced by
· AN/GRC-9, tunable, 2-12 MHz.
· SCR-510/BC-629, two channel, 20-27.9 MHz FM.
· SCR-610/BC-659, two channel, 27-38.9 MHz FM.
· SCR-619/BC-1335, two channel, 27-38.9 MHz FM.
· RT-70/PRC-16, tunable, 47-58.4 MHz FM.

The UHF Backpack for FAC (Forward Air Control)-Chart 3

Chart 3 - FAC UHF Backpacks

With the growth of civilian aviation and other services following WW II, there were some revisions made to the frequency band allocations. The Military Aircraft Band changed to high VHF/low UHF, 225-400 MHz. (It should be noted that foreign countries did not necessarily ever change over to the UHF band, making communications with their aircraft difficult when they were fighting with you.) The first portables to cover this new band were the MAY (Navy) and the AN/PRC-14 (Air Force/Army); both four-channel crystal controlled units. The MAY was a manpack unit, while the PRC-14 consisted of two main parts, a transceiver worn in the front, and a power supply with internal battery worn on the back. They were connected with a cable, and the antenna was mounted on top of the helmet. The synthesized (full band coverage, but in only 100 kHz steps) and partially transistorized PRC-41, another manpack unit, followed the PRC-14.

There was an effort by the Air Force during the mid 60s to develop prototype FAC units that would operate on all three tactical bands plus VHF Air. Rather than being a single radio with four bands inside, they were actually four separate radios, each with its own battery, fastened together on a frame, but arranged so they could be separated and operated independently if desired. Sylvania developed the PRC-71, while Bendix developed the PRC-72. Some number of units were produced (my guess is about a hundred or so) and tested in Vietnam. They hit the surplus market in the very early 70s, so their short life indicates to me a certain lack of success (too big, too heavy???). Later, there was a definition of a better system, the PRC-82, with the four bands designated PRC-83 through 86. All four radios were to be synthesized (the PRC-72 HF section was the only synthesized unit in the previous efforts, all the others were channelized with 2 to 6 channels). It appears that the PRC-82 venture never proceeded too far either.

Next, the Air Force developed the AN/PRC-66; a conventional backpack mounted unit. The Marines evidently did not want a backpack (perhaps because they envisioned an FAC with a PRC-70 (HF/VHF) or 77 (VHF only) on his back), so they went for a two piece design called the PRC-75. The radio and battery box fit into a two pocket front (belly) mounted canvas harness, and were connected with a cable. Both the 66 and the 75 were all solid state Collins Radio (USA for the 75, Toronto for the 66) designed units employing transistors, ICs and hybrid circuits to effect as small a size as possible.

Today we have the two-band Navy/Air Force PRC-113(V)3, which covers both aircraft bands. It allows for Air-band interoperability wherever you are, and whomever you are working with.

HF Backpacks for the Special Forces-Chart 4

Chart 4 - Special Forces Backpacks

It would appear that the first unit to reach widespread use was the partially transistorized (four tubes) synthesized AN/PRC-47. It is actually a two man portable (the second man carried the separate Silver battery in its case, amongst other things) with quite an antenna system for the occasions when a temporary fixed station is called for.

The all-solid state PRC-74 with its variants 74A, 74B and 74C backpack units followed this.

The dual band PRC-70, born out of the PRC-42 research effort, appeared next. It does not appear that it ever completely replaced the PRC-74. It also appears there are still PRC-47 and 74 units in the field.

The current HF unit is the IHFR (Improved High Frequency Radio) AN/PRC-104, with variants "A" (changed to LCD readout) and "B" (which added provisions for STAJ, Short Term Anti Jam).

Rumored to be on the horizon is the "Joint Tactical Radio."

SAR-Rescue Radios-Chart 5, PRC, URC, ICU, UCMe

Chart 5 - SAR/Rescue Radios

Many of these radios have seen service in roles other than SAR. Their small size lends itself to specialized communication duty, as evidenced in many of our conflicts, especially Vietnam.

It should be mentioned here for the purposes of completeness that the first life raft rescue radio was a code-sending transmitter nicknamed the "Gibson Girl". Nomenclatures included the BC-778 (SCR-587) and the AN/CRT-3. At 500 kHz it needed a long antenna, so it was furnished with both a kite and a balloon to loft the long wire. A chemical kit made hydrogen to inflate the balloon.

The Navy's AN/CRC-7 was the first two-way voice radio. Intended for life raft and other uses, it may have been used by the Air Force as well.

While in the midst of the aircraft frequency band plan change (see discussion in FAC section above), there was a need to have the SAR radios cover both 121.5 and 243 MHz. This made the radio rather large and heavy. The Air Force/Army went with the AN/URC-4 while the Navy went with both that and the AN/PRC-17. In a personal interview with a SAC Airman during this time frame, he stated that the mass of the radio was so large, and the jerk of the parachute opening so great, that "the radio and its battery ripped through the vest and kept on going upon chute deployment."

When the switch in frequencies was completed, the Air Force/Army went with the URC-11, while the Navy used that as well and also developed the PRC-32. Both of these operated on 243 MHz only and were much smaller than their two frequency predecessors. Since they still employed sub-miniature tubes, the battery was still big and heavy, however.

The push for a solid state radio resulted in the URC-10 (just one of many derivatives of the ACR designed RT-10 (243 MHz), such as RT-20A for training, (251.9 MHz), PRC-93 for the Marines( MHz), and the RT-60 (243/282.8 MHz)), which saw use by all branches, and the PRC-49 Navy developed unit, which most likely was the first all solid state rescue radio to make it into service. The Navy continued on and developed the ultimate in small size the PRC-63, the cutest little thing you ever did see.

However, the age of single frequency SAR radios had come to an end. The number of ELT (Emergency Locator Transmitter, sometimes automatically activated upon chute deployment) beacon transmissions crowding the 243 MHz frequency during battle in Vietnam proved the need for a second voice frequency, ultimately chosen to be 282.8 MHz.

The Air Force developed the URC-64 four-channel device. The Army opted instead for the URC-68, a four channel two-band (VHF/UHF) radio for helicopters that allowed downed airmen to communicate directly with ground troops as well as aircraft. Both of these were ultimately replaced by the Navy developed and improved PRC-90-1 and then -2 two-channel unit (243 and 282.8 MHz), the first tri-service SAR radio.

This was followed by a COTS (Commercial Off The Shelf) device from Motorola, the PRC-112. Sporting five different frequencies, circuitry was included which allowed equipment in the SAR aircraft (AN/ARS-6) to develop range and bearing information (DME), certainly a great help in aiding rescue efforts.

Current Para-Rescue (in the water, voice activated) radios include the PRC-103 AF unit, a spin off of the PRC-90, and the PRC-125 for the Navy.

The big news today in SAR is CSEL (Combat Survivor Evader Locator); a new Air Force managed tri-service program being run through Boeing. Racal has the contract for the new radio, which carries the nomenclature AN/PRQ-7. It will be capable of transmitting on at least 121.5, 243, and 406.025 MHz (the COPAS-SARSAT satellite tracking SAR system). It will also receive GPS information.

Meanwhile, Motorola produced 1000 pieces of an interim solution for use in the hot spots around the globe. It is called the HOOK-112, and it is a PRC-112 with an internal GPS (Global Positioning System) receiver that encrypts location data and transmits it upon demand to the SAR aircraft.

Non Tactical Portables-Chart 6

Chart 6 - Non-Tactical Portables

The Scope Shield program (AF run tri-service) is an exception. The second effort at providing a radio that would be interoperable with standard commercial frequencies made use of the AN/PRC-126 but changed the circuitry so that either 30-88 or 130-174 MHz could be covered by exchanging modules. This unit is the AN/PRC-128, and is an outgrowth of the early Scope Shield efforts with the PRC-68B(V) low band (the Marines also bought this one for tactical purposes)(10 channels programmable with independent Tx and Rx frequencies if required, 2.5 kHz steps, NB or WB as required) and PRC-68B(V)2 high band separate radios. (The PRC-136 fire rescue set appears to be another derivative of the PRC-68/126 programs.)

The Scope Shield II Program then developed the AN/PRC-139 with Racal. This radio can cover all three bands with module exchange, VHF low, VHF high, and UHF, all NBFM.

Multi Band Portables

Chart 7 - Miscellaneous Portables

1. The first was the AN/PRC-70, chart 4. It covers the HF spectrum as well as the Tactical VHF frequencies. Harris' PRC-138, chart 4 also, is a more modern type covering these same two bands. It is in use by U.N. Land Force Elements.

2. The already mentioned AN/PRC-113, chart 3, covers both the VHF and UHF aircraft bands.

3. The Scope Shield Program developed PRC-128 and PRC-139, chart 6. Unlike the others mentioned in this section, these two effect multi band coverage by module exchange.

4. Harris developed the PRC-117D, which covers the Tactical VHF (low) band, VHF high band (aircraft and mobile) as well as Tactical UHF (including SATCOM), chart 2. Note: SATCOM is effected using FM within the 225-400 MHz military aircraft (generally AM) band. The Marines and the Seals are apparently using some number of these radios.

5. The Motorola developed AN/URC-1xx series, chart 7. These are two band radios, all of which include the tactical UHF (AM) frequencies, including SATCOM (FM) as the first band. The second band can be tactical VHF, or high VHF, or ??? The Army is apparently using some number of the URC-100 for voice and the URC-110 for data. The Navy Seals apparently have some number of URC-110 sets also.

Unknowns

· Although the PRC-117 and URC-1xx units are described above, this is only the "what". The "why'" remains elusive.
· PRC-116, the Racal Jaguar V, 30-88 MHz ECCM unit, Racal #BC-66H
· PRC-124, a Collins MP-83, a PRC-77 type with 25 kHz channel spacing and FH.
· TRC-77 HF rig

Battery Technology

During WWII, there were only three types of batteries used in portables, Lead Acid rechargeable (for units with vibrator power supplies), Carbon Zinc for most of the rest, or Mercury (rescue radios only). Today, there are a bewildering number of chemistries out there, including but not limited to the following.

· Primary
· Alkaline, certainly low cost.
· Magnesium, on the scene until Lithium came along.
· Lithium/Sulfur Dioxide, the king of the hill for now.

· Secondary
· Lead Acid, liquid, gel, or starved electrolyte types, old venerable but heavy and has a tendency to sulfate.
· Silver, stayed for a short time.
· Nickel-Cadmium, lighter weight but has memory effect, usage is fading.
· Nickel Metal Hydride, twice the energy density of the NiCad, and with no memory effect, but expensive.
· Lithium Ion may be coming soon.

The goal is to obtain the highest energy density (watt-hours per unit volume (cubic inches)) at the lowest possible cost. Unfortunately, some of the highest performers are also the most expensive. However, some work over the past few years in Lead Acid technology has shown that proper charging techniques (pulse) can forestall sulfation, the chief cause of failure in this cell chemistry. Apparently, the increase in life can be up to 10 times. For a cash starved Military, this could be a Godsend. One of the unfortunate characteristics of secondary batteries, however, is that most if not all of them have a self discharge rate of 1-3% per day at 25 degrees C, worse as it gets hotter.

Comments by Dennis Starks-Note: This write-up has been changed to accommodate most of Dennis' comments

Forward

In The Beginning

Surely, it can be shown that the Navy has traditionally been far in advance of Army development all throughout radio communications history. Some examples, the Navy had in hand by 1939 the ART-13 (ATC), TCS, TBY, TBX, TBW, MU and the famous Command Sets to name just a few. All far and away more advanced than their Signal Corps counterparts BC-375, BC-223, BC-222, BC-654, BC-191, BC-611, and BC-229/230. It would not be until near wars end that the Signal Corps would catch up to the Navy and in some cases adopt Naval equipment. Similar examples can be shown to the present day. Perhaps a future series of articles entitled "Army Versus Navy" might be in order.

These facts however have been neglected in history, and overshadowed by Army variants for several reasons. First is the secretive nature of the Navy that prevented the commercial propagandizing enjoyed by the Army and its equipment. Second is shear numbers, while the Marine Corps had by mid WW-II a large selection of excellent equipment to choose from, their operational proximity to Army units by this time, combined by with the greater numbers of Army units and a difference in operational doctrines mandated that they (the Marine Corps) adopt and use those items of Signal Corps equipment most often needed to both enhance compatibility, and simplify the horrendous logistics problems associated with the support of such contingents in the field. Third was the support by manufactures at home. Manufacturing facilities at home were stretched to near limits. Every item needed to support the war effort had to compete for these facilities. The extent of this competition is very difficult to convey, but suffice to say it created extreme tension between ALL the services.

It should also be noted that Army Signal Corps, and Air force development were one in the same thing until the split of the Air force with the Army well after WW-II. Until then the only development or procurement effected by the "Army Air Corps" on it's own and without Signal Corps consent or collaboration was met with later disaster. A case in point was the Air Corps Jefferson Travis field radio sets that were ordered out of defiance without Signal Corps consent. The Jefferson Travis was much like a larger, more powerful SCR-284 (BC-654). Later during the North African Campaign, the Air Corps complained to the Signal Corps about the extreme weight of the radio set, and their difficulties in obtaining support and maintenance items. The Signal Corps replied in effect, this isn't one of our radio's, we did not order, nor approve them, therefore the logistic support channels do no exist in our system, I/E you shit your own nest now lay in it! The Jefferson Travis was then replaced in the field with Signal Corps types that had been designed for that same purpose rather than further clog up the logistic channels trying to support it. The same story can be re-told with several other examples.

FAC Radios:

The mid-late 50's saw a re-emergence of the TRC-7 in the hands of the Air force. This as a result of the realization that our move to UHF AM for tactical air communications had left the rest of the world behind, thus American FAC teams had no means of communications with allied aircraft. This condition persisted until the end of US involvement in Vietnam, and a steady succession of radios were either developed or purchased Off-The-Shelf and used as expedients to relieve some of the problem. Long before the Army/Air Force's fumbling along with the TRC-7, and PRC-14 (late 50's). The Navy had realized a need and solved it by late WW-II. This with the MAY (UHF AM) and the MAW (VHF AM), both these radios were backpack types that could also be set for semi-fixed operation with an elevated antenna. Though grossly obsolete, they would still be in the hands of Marine FAC/Pathfinder units until the late 60's. In the same light, the development of the PRC-41, and PRC-47 can be more closely credited to the Marine Corps who was by far the largest purchaser, rather than the Army or Air force.

It should be noted that FAC operations have the peculiar need to be able to operate on all bands, I/E HF/AM (later SSB), VHF/FM, VHF/AM, and UHF/AM. This led to the Air force's development of the PRC-71, 72, 83 etc. None were built in very significant quantity. The Army and Navy on the other hand chose to stick with an assemblage of the more common tactical sets PRC-25/77, 74, 47(Marines), and 41. In addition, history will show that virtually all the common radios originally developed as Downed Airman's, or survival radios, also saw secondary duty in use as a front line means of fighter control often in the hands of Special Forces Teams, and other Irregular Forces. These include the URC-4, 11, 10, 10A, PRC-63, 90, ACR-RT-10 and a long list of others.

It is true that very little is known of the Pre-SSB days of the front line foot FAC units. We do know that the GRC-9 was used in this capacity while vehicular, and was most probably dismounted for close-in use. The possibility also exists that the GRC-13 might have been used in this same role, and if so, might account for its extreme rarity today. While the Marine Corps did have access to GRC-9's, their TBX series remained in service at least until the end of the Korean War, and evidence exists that place it in use even later. It is very doubtful that either the GRC-109, or the PRC-64, ever saw service in use by FAC units. This because the primary mode for both of these radio sets was CW, and voice communications were needed for spontaneous aircraft tactical coordination. Also the history of the GRC-109/RS-1 in military hands has been well documented via this forum and precludes any such usage. Another contributing factor in the development of FAC equipment is that Air force FAC units, unlike Army FAC's and Marine Pathfinders seldom advanced into the extreme forward areas that would require the use of backpack equipment. Thus, most of the equipment used by them was vehicular in nature. Beginning in WW-II, a tradition of retrofitting aircraft radio equipment into ground vehicles started with the SCR-522, which, after being installed in tanks, was called an SCR-524. This practice mushroomed after WW-II with 24vdc(compatible with 28vdc aircraft) becoming our military's standard vehicle voltage, and still lives on today, the variations of equipment used would fill several volumes, and include HF, VHF, and UHF examples of every type and vintage.

PRT-4/PRR-9/PRC-68:

The PRT-4/PRR-9 combination remains extremely significant to history for several reasons. First and foremost was the technology they represented including the first in an all solid state radio set, and second the use of a 10.7mc IF frequency which is now standard, and lastly the first use of an Integrated circuit (IC), this is the 150cps tone generator on "A" models. The story told in the development of these radios is an unequaled example of Government Bull Shit, and non-cooperation.

The PRC-68 was the direct result of the adoption of the PRT-4/PRR-9 and not because of any obvious reasoning. But out of the disgust felt by the Marine Corps having been totally ignored during the entire developmental process even though this was a joint services project. Their grievance was not with the basic design of the radio set, or its performance, rather it was with the dual radio packaging and limited channel capacity. I/E the Marine Corps had all along pressed for a channel capacity of at least four and a radio housed in a single cabinet. Had their wishes been headed during the Development of the PRT-4/PRR-9, we might not ever have received the PRC-68's, or at least not until a much later date.

In the interim years between the PRT-4/PRR-9 and the PRC-68, another long list of radios were developed, and or purchased as emergency expedients in very limited quantities. Some of the later include some international joint development units such as the PRC-601, and 602 a joint Israeli/US, Tadiran/GTE venture. At least four solid state versions of the PRC-6 are also known to have been purchased by the US government, two types of German origin, and two of US.

Downed Airman's/Survival Radios (SAR):

Second to emerge was the CRC-7. While it is true that the radio was used in life raft during the war. It's greatest claim to fame was it's use aboard fighter aircraft where the available space for such equipment was at a premium (the CRC-7 was a transceiver shaped like a large cigar tube, approx. 2" in diameter, & 14" long). In postwar years, it would receive expanded use in light bombers, and with commercial airlines.

The Army/Air force/URC-4 use combined with the Navy/PRC-17 use can be debated to some extent as numerous examples of the URC-4 survive to show Navy use. In addition, most surviving examples of the PRC-17 show use by commercial airlines. Further, the URC-11 /Army/Air Force and PRC-32/Navy associations can also be debated. It would appear that the Naval purchase of the PRC-32 was a simple expedient to augment supplies of their URC-11's at a time when technology was awaiting the advent of an all solid state radio. I/E, a limbo period existed between the URC-11 (all tubes) and the first solid state SAR radio. During this period a long list of Make-Do radios were purchased, tested, or used. Some of these were even commercial Off-the-Shelf types including many ACR built variants. It should be noted that all these early SAR radios (except the CRC-7), even the first and second generation ACR types, used and external, metal incased, battery that was connected to the radio via an umbilical cable, making for a very cumbersome arrangement. The first solid state SAR radio was not the ACR-RT-10, or the URC-10 (both being the same radio). The first model RT-10 was in fact a tube type radio and used a separate battery just as previous designs [Information from the manuals indicates Dennis is not correct here in fact, all these three sets were solid state]. The second version "A" model, though physically identical to it's older brother was indeed all-solid state. It was adopted by all US services with various markings including ACR-RT-10A, URC-10A, and PRC-93 [It appears there was only an RT-10, no "A" version is known to exist]. Apparently due to it's high production cost it did not fair well in military service.

The Army's URC-68 was never intended as a one size fits all SAR radio. It was expressly intended for use by helicopter flight crews and with their close operational proximity to ground troops, the low-band VHF/FM band was included. At one time it was briefly considered by the Army Rangers as a "Stop Gap" radio to fill the void they felt for lack of a suitable squad radio. It was however quickly dismissed as too fragile for this type use.

The Navy PRC-63, though it did enjoy some popularity and use, was a hermetically sealed throwaway radio. Built completely from synthetics, it was very light weight, compact, and possibly for the first time in large scale, used a "Rubber Duckie" type antenna. But it's synthetic materials rendered it fragile, and its being permanently sealed prevented any attempt at servicing. It gave way in short order to the PRC-90.

The Navy's improved PRC-90-2. The only difference between the PRC-90s used by the Navy/Marine Corps and those in use by the Army/Air Force was in the process used to manufacture their cabinets. Both radio variants were built in the same factories at the same time, on the same production lines. The difference is in the type aluminum used in the cabinets on each variant. Those used by the Army/Air Force have an aluminum cabinet that began life as an investment casting. On the other hand, Navy/Marine Corps cabinets are completely milled from a solid block of aluminum. The end result of the Navy/Marine manufacturing process was a radio that would survive being submerged in water to a greater depth.

Even by the late 50's-early 60's, the military had not completely weaned itself from some dependence on the VHF (Civil) aircraft band. The URC-14 is identical in every respect to a URC-11 except for one; it operates on 121.5 vice 243mc. This can be seen again with the current PRC-106, a radio that is physically identical to the PRC-90 except that this one is dual band and operates on both 121.5, and 243mc. Has anyone ever noticed the harmonic relationship between all the aircraft Guard frequencies? We have 40.5mc FM used in helicopters, times three equals 121.5 for the civil aircraft band, time two equals 243mc military guard. Coincidence?

Back-Pack Radios:

The PRC-8, 9, 10, not only offered much greater frequency coverage with less signal bandwidth, and a smaller size and weight. But also introduced the first examples of modular design into a military radio. This greatly simplifying field service and logistics, and provided some measure if interchangeability between radio parts and accessories. The Canadians, Dutch, and Australians would ingeniously expand on this system in their same generation of equipment to include their Squad Radio, the CPRC-26. Which used common components, and accessories with not only their own versions of the PRC-8, 9, & 10, but also US radios. The US would not follow their own lead with our PRC-6, which included none of this interchangeability. Another "First" for the PRC-10 family of radios, and possibly most significant, was their Steel Tape antenna that would become an international standard to this day.

The PRC-25 is the single most significant contribution to military tactical communication of it's type since the advent of the SCR-300 (BC-1000). It and it's immediate successor the PRC-77 would become the most proliferate radio in military history spanning almost 30 years, 40 countries, and countless manufactures foreign and domestic. It would remain the standard for comparison long after it's obsolescence, and still remains in widespread use today. Besides being the first solid state FM backpack radio, it also introduced the now standard 150cps tone squelch system which effectively "Grunt Proofed" it not only simplifying operation by untrained personnel but also reducing front panel controls to a minimum.

The PRC-119 is by ALL accounts, especially those taxed with it's operation, a horribly over complicated, and temperamental radio set. I personally cannot perceive it's longevity as a replacement for the PRC-77 excepted in higher echelons where communications security is of utmost importance and the personnel that are highly trained for it's operation, and support are available.

Multi-Role Radio Equipment:

The reverse is true of such radios as the BC-1335 and RT-70 whose portability was secondary to their primary mission as a vehicular radio.

Special Forces Portables:

The first and second radios to be developed for use by any US Elite Force were the PRC-1, and PRC-5. Both Classic Suite Case type radios, the PRC-1 arrived early in WW-II and is responsible for being the backbone of both tactical, and clandestine communication in the China Burma theater, not only by groups such as "Galahad, and "Merill's Marauders", but also the OSS Special Operations Group 101. Not the SSTR-1 which has received the credit for this activity. The PRC-5 arrived about mid-war, and while its exploits are not documented at all, evidenced does exist to place it too in the China/Burma Theater.

The BC-611 (SCR-536) was also originally designed expressly for use by Airborne troops. But as we know, it was later used by virtually every service, and every Allied country, in every theater of WW-II.

The third known radio to have been designed expressly for Special (Elite) Forces was the BC-1306 (SCR-694C). Being originally designed for use by Airborne and Mountain troops, it was later pressed into service with all branches of service due to the major shortcomings of the BC-654 (SCR-284). The SCR-284 shortcomings were indeed so great, that semi-experimental versions of the SCR-694 were placed into early service, the BC-1136 (SCR-694AW).

At the same time SCR-694 became available, so too did the TRC-2. Originally intended for service with Military Intelligence, this was a combination of the a standard BC-1306 with it's lower frequency twin, the RT-12/TRC-2.

Next came the already described TRC-7 also intended for use by airborne troops, followed closely by the TRC-10. The later was a re-packaged version of the PRC-1, which allowed for a far more versatile operational package. At a glance, it was similar in appearance to the SCR-284 but boasted a much wider frequency coverage, and CW only operation. This radio today remains one of the rarest, and most difficult to document of all military radios.

Somewhere in this mess came the PRC-4, about this radio we know nothing excepting that it was a discized version of the SCR-536/BC-611, also intended for use by Military Intelligence.

The Army was not the only military organization to employ specialized radio equipment for its Elite forces; the Navy too had such equipment even in the early days. However due to the typical secrecy veil that shrouded all Naval equipment, documentation of these types is the most difficult of all. Only two radios are known to have seen service with these type forces. The first was the common TBX whose exploits are only now beginning to surface. The second, also of WW-II vintage was the MBM. A suitcase-like radio set design for use by forward raiding parties. It should be noted that the Navy maintained clandestine operations in all Pacific theaters that were rivaled by no other organization foreign or domestic. And lest we forget the vulnerable MAB, or as it is called in it's own manual "the Para-Talkie", being pictured in used by a Para-Marine (though it is unknown whether the radio saw any use with this short lived branch of the Marine Corps). Post-War years saw the Army Special Forces using the CIA's RS-1, and the GRC-9. It was not until late 1962 that the RS-1 would be officially adopted as the GRC-109 and a regular Army Standard Issue item. And then only because of the transfer of operational control of the Army Special Forces from CIA hands back to regular Army. Contrary to popular belief, the GRC-109"A" model was not an adaptation for code burst operation. It was in fact the same radio supplied with a different "Armor" cabinet that was more than twice as thick as the previous model, with a corresponding increase in weight. By the time of the demise of the RS-1/GRC-109 they had nearly all been either supplied from the factory with code burst capabilities, or this feature was added by way of an MWO [Modification Work Order].

Following closely the adoption of the GRC-109 came the PRC-64 in 1965. Again a radio of CIA origin via the Delco 5300. While the widespread use of the PRC-64 in US hands may or may not have been short lived, and is open for debate, it did enjoy extreme popularity in the hands of one of our few Vietnam Conflict Allies, the Australians and their Special Operations Group. With the introduction of the "A" model with enhanced code burst operation, it would appear that all or most previous, models where modified to comply to the newer radio's specs in the same is respect as it's predecessors the RS-1, and GRC-109.

But before this, with its beginnings in question (approx early 60's/late 50's) came the simi-experimental TRC-77. Receiving its TRC designation via WW-II tradition, it too was originally intend for use by Military Intelligence, and Special Forces. However by this time, its intended US constituency had become highly disillusioned with any high tech/new fangled contraptions. It was then relegated to use by South Vietnamese commandos who were extremely active against North Vietnamese coastal installations. We have also recently learned, via this group, of possible Australian use.

The PRC-62, while for some years it was in question whether this radio actually existed, and the few surviving references to it were simple type errors or just wishful thinking. Recent events, again via this forum and our Aussie members have proven not only the existence of this radio, but also it's use by both the US and Australian militaries.

The author makes mention of the PRC-52, and PRC-42. Both of these are new ones to me, and I'm most interested to learn more about them. In the mid 60's to early 70's, a long list of SSB radios were acquired for testing in South East Asia (over 200). Tracing them down has been close to impossible. Every day somebody comes up with another possible candidate. Suffice to say that there were many radios acquired and used by every involved service. Some to the extent they received almost Standard type acceptance. Some familiar names include AVCO, Hughes, Southcom, Hallicrafters, Harris (RF), Motorola, Collins any others.

It should be noted that the use of HF communications equipment by Special Forces tactical units was primarily NOT to provide "very long distance communications", as the layman might understand it. While radios of this type were capable of long range communications when in competent hands, the primary mission of an HF portable in the hands of any front line tactical unit was to provide communications at ranges not possible with VHF FM equipment of the same type. I/E 1-5 miles for VHF/FM types, 5-10 miles for the HF types. These distances generally represent those that the unit in question might be separated from either its next higher Echelon, or companion units. Typical extremely long rang communications with this type equipment in Vietnam were on the order of 20 miles max.

Off-The-Shelf Security Radios:

Dennis Starks; MILITARY RADIO COLLECTOR/HISTORIAN military-radio-guy@juno.com.

References and Other Sources of Information (in no particular order)

NJ7P/February 2000