Historia de las radios norteamericanas (en ingles)

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Historia de las radios norteamericanas (en ingles)

Notapor Patman » 11 Jun 2011, 22:47

Encontre este texto en la web y me parecio muy interesante.

http://www.armyradio.com/arsc/customer/ ... mments.htm

Additional Comments by Dennis Starks

Dennis R Starks, military-radio-guy@juno.com

Conclusion by Dennis Starks
Forward:
I realise that the author's intent in the first parts of this series was to give a casual account of the development of selected portable radios beginning in WW-II and progressing to the present. However, things being as they are, and me being the ass hole I am, I just couldn't leave it at that. I felt that several things should be covered in more detail, and a couple half-truths dispelled. It is my sincere hope that further, more detail discussion may be the result of publishing this material. Comments from everybody, regardless of content are most emphatically sought.

In The Beginning
The SCR-511 was not developed before the SCR-536, in fact, the SCR-536 was undergoing field trials before the SCR-511. As has been covered in great detail via this forum, the two radios were designed with two completely different intended purposes; it was fate that joined them as companions in the field. In addition, the Navy had fielded the MU (early MAB) before the advent of either.

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 propagandising 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 Air force lead in the development and use of an FAC radios can be debated in depth. Considering the WW-II developmental practices outlined above, the first true FAC radio was the TRC-7 of mid WW-II vintage, developed for Military intelligence, and Airborne troops (not the Air Corps) as both a liaison radio for air support, and later as a means of fighter control for extreme forward area ground troops. It was indeed a backpack radio operating from the same battery as a BC-1000, and provided with a very large array of accessories that allowed it's use as a semi-fixed station, even a hand crank generator was available. There is also evidence to show that the CRC-7 (the first hand -held VHF AM downed airman's radio) had been used as an expedient by Airborne troops even before the advent of the TRC-7 ( more on the CRC-7 later ).

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 realisation 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 realised 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 co-ordination. 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
It is true that there was a long drawn out research effort that resulted in the Marine Corps PRC-68. But this was preceded by an even longer effort to develop the PRT-4/PRR-9, beginning in 1950 and ending in 1964. This effort produced the experimental PRC-15, 30, 34, 35, & 36. While it is true the PRT-4/PRR-9 saw little actual service in the field, it remained the only official squad radio of record until at least 1977, when only experimental versions of the PRC-68 were yet available.

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 unequalled example of Government Bull Shit, and non-co-operation.

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)
While there was a succession of survival type radios used before during and after WW-II, the first such radio adopted as a Standard Item was the legendary Gibson Girl of WW-II fame. A direct copy of a German set that had bee captured in the North Sea by the British, then remanded by them to the US for development and production. It remained in service aboard large aircraft and all sea going vessels with very little change until the late 80's and the demise of the 500kc marine distress band, combined with the negating of Morse Code proficiency of licensed marine radio operators.

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 post-war 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 aluminium used in the cabinets on each variant. Those used by the Army/Air Force have an aluminium cabinet that began life as an investment casting. On the other hand, Navy/Marine Corps cabinets are completely milled from a solid block of aluminium. 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?

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.

Back-Pack Radios
The BC-222/322(SCR-194/195) along with the TBY were indeed Backpack radios, and as such designed to be operable while in motion on the operator's back (though admittedly a very precarious operation for these particular radios). Followed by the SCR-300 (BC-1000) which would set the stage for ALL front line tactical radios to follow, even to this day.

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 inter-changeability 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 inter-changeability. 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
While the concept of a multi role vehicular/manpack radio system is indeed an old one, it still enjoys great popularity today world-wide. And too, while it is true that such radios as the BC-654, 620, 659, 1306, GRC-9, TBX and a host of others, were adapted for use in a vehicular mode. Their primary design intent and purpose in life was as a Field Portable/Man-Pack radio set and not a vehicular one. In the case of the TBX, though, power supplies existed which allowed vehicular use, but no mounting hardware for either the radio or its ancillary equipment were ever produced. Vehicular installation instructions for this particular family of radios amounted to templates by which plywood mounts could be cut.

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
It is true that early equipment specifically designed for use by various Special Forces groups are hard to document, however much information has been gathered on both the earliest and latest sets to see their use, with only an interim gap between the GRC-109/RS-1, RS-6, GRC-9, and the WW-II PRC-5.

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 theatre, 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 Theatre.

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 theatre 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 organisation to employ specialised 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 theatres that were rivalled by no other organisation 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 "Armour" 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 semi-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.

Dennis Starks, Military Radio Collector and Historian
Military-radio-guy@juno.com
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