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As for where these “obsolete, less than ideally designed” wireless systems found their most use, it was in tactical environments. Typically the Infantry Divisions, with their need for supporting ground and artillery backing, found the most need for these systems. Later, as Patton and others refined their tactics, the Armored and Cavalry divisions began to focus in on integrating radio communication into their plans. Last but not least came the coastal defense sites, and the new air groups and squadrons.

As to what pieces of equipment made it to these services, strangely enough they were thought of as the three oldest communication sets in the logistic network, while in truth they were not much older than most of the wireline gear being used at that time. Even so, because the research engineers back at Monmouth thought of them as representing old technology, they were referred to that way.

To be fair to the both sides, the early radio sets brought online were more than adequate for the purpose intended, although the Monmouth engineers were right when they said that these systems wouldn’t make it through the entirety of another war unless improvements were made. Still… the reader should remember that at the time these decisions were being made, no one yet knew that WWII was on the horizon.

The units that first hit the tactical front line proved to be the SCR's 131, 161, and 171. (To read or download a copy of the 1942 version of TM 11-237, which covered SCR-131 and SCR-161 click here: TM 11-237.)

Anyone who served in WWII will remember the astonishing SCR-131…  not so much because it saw service in the actual war, but because it was ubiquitous in the wartime service and training camps of the time. Together the three of them… the 131, 161 and 171… saw extensive use in training and introduced the concept of radio communication and basic electronic circuitry into the heads of thousands of G.I.s.

Based on continuous wave, short-range, loop antennas, both the portable and “semi-portable” models were quick to be taken onboard by the units they were sent to. Mostly used at the regimental level, the 131 was sent to the Infantry and Cavalry. The SCR-161 found service with the Field Artillery, and the much heavier SCR-171 ended up with the ground-to-air control people, and occasionally up and into Division level Headquarters.

Supporting these three base level sets the Signal Corps introduced a second group of radios intended to be used on the ground, in more mobile environments. Designed for point-to-point and ground-to-air communications, they employed superheterodyne receivers, something new to the military. Known by the designations as the series 177-78-79 and the 188, they were primarily meant for mobile point-to-point ground use but ended up being used for stationary ground use too. Their benefit over the 131, 161 and 171 was their longer range. Their detriment was that moving them from one place to another required a Jeep or Three-Quarter ton, or, as with the 179, a horse would do in a pinch.[1]

Of these point-to-point systems, the SCR-177 was quickly picked up by the Coast Artillery Corps. Used in places like Hawaii, where it was spread liberally along the island’s coastline in support of the many 16 inch guns installed to repel a seaborne battleship attack, as well as in Cuba, the Philippines, Panama, along the coast of the U.S., and a few other places, including as far away as Tinian and Fiji, it proved a reliable and effective set.

 

The 178 found its way to the Field Artillery and the SCR-188 became the baby of the early Army Air Corps. For their purpose, all three sets worked well in these rather stable and non-mobile environments, with the transmitters pushing out up to 75 watts of power. With this much power, sustained Morse code could be sent  by either continuous wave or tone signals. Best of all, the code could be heard at distances of up to one hundred miles. This proved valuable in those war environments where this form of signaling provided communications that could not be obtained with normal ground receivers.

Yet while the Morse capabilities of these early sets was good, their voice transmission capability was just so-so by today’s standards. Mostly limited to twenty-odd miles, it proved useful only in non-fluid front line environments and the obvious rear echelon areas where men and equipment didn’t tend to move too quickly or too often.

This was because voice communication on these three sets used the upper reaches of the middle frequencies and the lower reaches of the high frequencies. In other words, they operated primarily in the bands just above broadcast… except for the 188. The 188, again, an Army Air Corps ground set, was tweaked for its intended use by re-calibrating from its original range between 6,200 and 7,700 Hertz, to extend this range both up to the 1.5 megacycles area and down to 1,500 kilocycles. As such, it had an impressive range and could easily find a way… one way or another… to communicate with the fly boys who needed most to know what was going on.

In terms of being portable… at least as we know the term today… they were not. Each weighed in at a hundred pounds or more. This, plus the need for gasoline powered power generation, a dynamotor, and a rather large (up to 30 foot mast level) signal antenna made them strictly ground borne… even for the newly arrived Army Air Corps.

As a check and balance on whether this was a problem or not, the reader should remember that prior to the start of WWII, the soon to be enemy was in no better shape. The problems in terms of reliability, range, and portability that the U.S. sets exhibited could be seen in those being used by the Germans too. The German 80 W.S.2, for example, suffered the same limitations, although the U.S. did not know so at the time.

Regardless, the Signal Corps was riding herd on communication development between the wars and meant to leave no stone unturned until it had what it wanted for the troops and sister services it supported.

While the Signal Corps pressed on with research and development of better means of radio communication, the SCR-177 and the SCR-188 found themselves becoming part of the military teams they were sent to for many years to come. Yet while their base capabilities changed little, their use did see change as the Signal Corps introduced to the supporting services more effective ways for field tactics to be adapted to make better use of the type of communication these sets made possible.

For example, with the Army Air Corps, while the sets were principally intended to function in support of air power, the Signal Corps recognized that the real need was for mobility. Knowing what others did not… that newer sets were on the horizon… it began laying out better strategic uses of communication to the Army Air Corps even before the next generation of radios were ready. Some in the Air Corps complained that the new processes being introduced by the Signal Corps didn’t fit the units then existing strategies and tactics, but the Signal Corps knew well that once it brought to the field more advanced and more portable radio sets, the Air Corps would find itself in just the opposite position… where its strategies and tactics couldn’t make use of the power these new sets brought to the unit. To forestall this the Signal Corps swallowed hard when criticism was leveled at it, listened to the criticism, kept its head down, and kept pushing for the introduction of tactics, strategies and processes that would be able to take full advantage of the capabilities of the newer radio systems being readied for launch.

The reader can sense that while the landscape of the radio communication systems in the field was stable, dramatic changes were underway behind the scenes. In synchronization, services like the Army Air Corps pushed the limits of what the Signal Corps could provide, while at the same time the Signal Corps challenged the fundamental tactics that were being used by the Air Corps at the time, as it sought to achieve that one impossible answer all engineers face when developing new products for their customer: does the customer know enough about what is possible to be able to tell us what they need, or do we need to learn enough about how they operate their “business” just so that we can then explain to them what is possible in words they will understand, so that together, we can then figure out what they really need?

What few in the services knew at the time was that on the horizon the Signal Corps was readying exceptionally portable sets, mobile sets, crystal-controlled sets, and frequency-modulated sets… all of which would revolutionize the U.S. military and push it far ahead of the rest of the world’s militaries. As the Signal Corps drove forward in pressuring the Army Air Corps, Armored and Infantry arms to upgrade both their strategies, tactics and operational control processes to make use of the new features and capabilities soon to be introduced, the others fought back, saying that everything they were doing was just fine.

Or so that’s the way it was until the Signal Corps brought online equipment that made possible excitingly new tactical concepts that could be supported by what came to be known as the 500 and 600 series. These new radio sets were brought online between 1939 and 1942-43. They replaced almost the entire range of the older 100 series, filled in (where needed) around the edges for the older 200 series, left most of the 300's and 400's as they were but ready for improvement later in time, and otherwise made possible a whole new form of battlefield communication unheard of until then.[2]

If you ask an old soldier or two today, a few might remember something about new radio communication sets coming to the field in the early days of the war, but most won’t. Where it was noticed the most was in the rapid change they brought about in airborne operations. Then an almost wholly new branch of the armed forces, the fly boys that populated it were open to any kind of experimentation, and being technically sophisticated, they absolutely loved the idea of newer forms of radio communication. In fact, after the war when HAM Radio operation became popular, there were more Hams from the old Army Air Corps than any other branch. Most were former bombardiers, who also operated the radio sets on most missions.

It’s because of this that while the old SCR- 131 continued to be used in many parts of the military, its colleagues the 161 and 171 soon fell from grace in services like the Army Air Corps. In trying to understand what caused this, it should be remembered that while today the military lives and breathes integrated service operations, prior to the WWII this concept was foreign to most military men, and especially the boys in aviation. For them, the thinking was that aviation was far too different a beast from the other services to be able to get by on hand-me-down equipment from the Artillery or Infantry branches. The Signal Corps new this, and being responsible for the successful birth of the Army Air Corps, was determined to give its new child everything it needed.

In doing so, one thing that that became obvious was that the radio equipment of the 1920's simply wasn’t up to the job of supporting effective ground to air communications. The old 134, the liaison set the Signal Corps had initially assigned for bombers, quickly proved inadequate and had to be replaced by the 187, which in turn required further modifications before it would serve its purpose. When the 187 was finally modified sufficiently to operate well it was re-designated as the 287. Because many of these modifications were done after the device left the factory, while internally it might have been a 287, externally it still looked and usually carried nomenclature tags that branded it a 187.

At the time this was not a problem, but it sure proved troublesome as time passed, the war ended and military surplus began to appear on the streets. Prior to and during WWII the morphing of the 134 into the 187 and then the 287, with barely a thought being given as to how to distinguish one from the other, what labels they carried, or how they were designated was of little interest or consequence to anyone. For the commanders of the time the objective was simple: get the communications working! It was not: be sure to create an auditable historical record of what was what, what it was called, what other pieces of equipment it worked with, when everything was introduced, and in what order. That could be sorted out later… if these early systems were even around by the time 1945 arrived.

Unfortunately, as time passed and military historians began to look back on these years and investigate the equipment used during them, they ended up having a devil of a time figuring out what was what when it came to Signal Corps communication sets.

The kind of “loose labeling” of systems and equipment that occurred in the late 1930s, something that was an acceptable expedient at  the time, is what led to the mess we have today where historians and technical-obsessives scour the world for old U.S. Army commun-ications gear and try to figure out what it is and what it's called. This inability to accurately tell what a piece of WWII communication equipment is, we now know, comes from the fact that the name plates frequently said one thing while the guts inside, which were likely upgraded in the field, said another. And it's because of this that military historians of today have fallen back on designating early Signal Corps radio sets on the basis of their manufacture date. Since manufacture dates can usually be found on a place somewhere on the chassis, most people think this is a safe way to classify these signal sets. Yet we know it is not. Yes, it might tell you when a particular device left the factory, but it certainly does not tell you what the military of the time thought it was or how it was used. For as we now know, the majority of the SCR-187s that are out there today, collecting dust in some hobbyist’s home or military museum, are in reality not 187s but 287s in disguise.

As to how valuable the SCR 187-cum-287 was, and why there are still so many of them on the market today, its first use (as a pure SCR-187, not as a modified 287) was at the first inauguration of Franklin D. Roosevelt. There it was used to provide a nationwide broadcast providing an aerial view of the ceremony.

The next year, if anyone had been tracking it, they would have seen an SCR-187 aboard the pioneer 1934 flight of Army Air Corps’ bombers to Alaska. There, as a platform for long-range airborne communications, it proved sound and capable of the task. Its transmitter was so dependable that it was employed for ground use as well, acting as a base for communication with early military vehicles.

It wasn’t until the early days of WWII when modifications began to filter through to the field that the SCR-287, or as it was known in the Army Air Corps, the BC-375, began to appear. At that time GE set about manufacturing tens of thousands of them. As to where it found its most prevalent use, it was on B-17s... the plane that led the war effort.

When used in B-17s the SCR-287 consisted of a complete set of equipment, including what was called the BC375 transmitter, a BC-348 receiver, and usually a Lionel J-47 telegraph key. For ground use, the BC-348 was usually replaced with a BC-348-Q receiver, which had its own dynamotor, that in turn was driven from a 24 volt battery supply. This wasn’t needed in the B-17s, as power could be harnessed from the four 1,200-horsepower Wright Cyclone Model R-1820-97 engines. Massive and powerful, the engines were nine cylinder, radial, air-cooled, with a 16:9 gear ratio. The propellers they drove were three-bladed Hamilton Standard propellers, 11 feet, 7 inches in diameter. Finally, to top out the SCR-287 package, in the air headsets were used, while on the ground carbon microphones and speakers were most common.[3]

One interesting element of this was that when it became obvious towards the middle of the war that technology changes were needed and the older chassis then being manufactured should be replaced with new chassis and component configurations that allowed ease of modification, no one thought to stop production of the older chassis/equipment configurations. The result was that by the end of the war thousands of BC-375-E (the Army Air Corps designation for the GE manufactured SCR-287) transmitters sat around unopened and in pristine condition in their original crates. These then were the source of many of the SCR-287s that made it to Radio Row in Manhattan.

It was at this point in  time when another point of confusion began to set in for future historians. Overall the SCR-187 was a fine radio. With modifications it could be used on the ground, in the air, for long distance communication, short range, with batteries and a dynamotor, or without by using local power. If the modifications were built into a production run of the chassis it might received a new designation, then again it might just get a letter designation added on to the old name. Sometimes a manufacturer added a new name plate, but only when he had to buy more because his older inventory ran out. Other times he just didn't bother. Thus, by the time what we call the SCR-187 hit the field, it could be designated based on who manufactured it, what modifications it had, what it was designed for, or left up to the devices of the Army Air Corps to call it what they wanted (which usually depended on what other equipment it was packaged with), or even the Navy... who usually wanted no part of any letter-number designation system invented by the Army. This, plus the problems caused by our earlier discussion above, makes it nearly impossible for anyone today to truly know what they have in their possession unless they were able to read electronic circuit diagrams and cross reference them to what is actually installed in the chassis of the set.

Regardless of all of this however, whatever it was called, underneath it all it was still an SCR-187, and while various designations appeared and faded along the way, in the end the basic SCR-187 continued to see long use well into the war, no matter what armchair historians tell you.

For example, while late into WWII the SCR-187/287 started to be replaced with newer designs for use in long-range aircraft, the original receiver stayed in use. Here we can see clearly that while the designation changed, the basic receiver and all of the associated equipment that made the core system work stayed the same. As for the reason the receiver was not upgraded or replaced, its ability to support changes in frequency band usage meant that it found both tactical and logistics utility.

Specifically, realizing that the Army Air Corps frequently wanted to switch to new frequency bands, the Signal Corps’ Aircraft Radio Laboratory guys decided that rather than design a new system they would simply modify the SCR-187 so that it used plug-in tuning coils. The same could not be done with the transmitter, and so the transmitter was replaced while the receiver was simply modified. With this simple step it was now possible for the Air Corps to remove one coil assembly and plug in another and get the frequency band they wanted, while the military in general could avoid having to logistically manufacture, supply and retrofit the thousands of units in the field. Remember, the Signal corps was responsible for much of WWIIs logistics management at the time, and so issues like this were important.

Yet while this need for long-range communication and band switching prevailed with long-range bombers in the Air Corps, that was not the case with other aircraft that depended on short-range communication systems. Because of this the 187 was modified again so that it provided more effective short range communication, and was re-designated as the SCR-183. Working well, and without any real need to be upgraded as a communication device, other evolving technologies came along that forced yet another change in the underlying technology: the 12-volt batteries that were standard in aircraft at the time began to be replaced with 24-volt batteries.

With this change the SCR-183, which operated off of 12-volt storage batteries (as the 187 did) needed to be modified one more time. This time it was called the SCR-283, and sent to the field to replace the SCR-183, a perfectly good radio system that was set to pasture by changes in other technologies. In the end however, even this change did not meet the needs of short-range aircraft, as the SCR-183/283 still clocked in at only a bit less than fifty pounds. For a pursuit pilot heading into aerial combat, light weight was more important than being able to communicate. The result was that most pursuit aviators simply yanked their radios out of the plane, replaced them with an equivalent amount of machine gun ammunition and/or bombs, and headed up into the skies.

Other technological changes came along that finally forced the SCR-183/283 death knell to be sounded. That was the introduction of pursuit aircraft with the ability to fly beyond the range of the radio set. Because the SCR-183/283 used continuous-wave transmission, its maximum range fell in around forty-five to fifty miles. Newer pursuit planes proved able to pass beyond that in just a few minutes of flight. It was because of this that around 1943 newer radio sets began to be delivered. Even so, let’s remember that underneath all of this the SCR-183/283 was still basically an SCR-187 at heart.

To help make sure that as newer associated technologies advanced (aircraft) radio design could keep up, the Signal Corps established an Air Corps Technical Committee to chart the way forward. These folks were the ones that proposed a fundamentally different approach in the core technology used to support command and control communications (referred to simply as Command Sets, when the topic was about the equipment itself), and it was at this time that the old SCR-187/287 saw a tombstone put on its production.

What the Technical Committee decreed was that going forward both the transmitters and the receivers in the new sets were to have crystal control instead of tuning coils. Heresy to many radio operators of the time, the ability of this approach to preset a frequency range via a crystal nevertheless allowed for not only the automatic finding of frequencies but the easy selection of what were called “channels.” Those readers who can’t live without their remote control TV channel changer firmly in their hands (versus their wife’s) should stop here and thank the Signal Corps for making the remote control possible, and especially for bringing the word channel into everyday usage. However, little did anyone at the time know that by doing so they were creating the single most important daily point of friction and argument for every family in the world today. Hoo Ah! Thank you, U.S. Army Signal Corps, for adding this most important word to our daily vocabulary and causing as many family arguments as you have over what channel Dad will designate that the family will watch.

Returning to the main topic, with a few other changes thrown in to extend the range it was not long before people were talking about a new radio set, to be designated the SCR-240, being made ready for field use. Traditionalists aside, the Army Air Corps was ecstatic about it, because it promised to relieve the pilot of the delicate business of tuning a dial to find a frequency. Remember, in a pursuit aircraft the pilot was also the radio operator. Giving him the ability to simply press a button or flick a DPDT switch would let him focus on the real job… shooting down the other guy.

And so everyone in the Air Corps waited impatiently for the SCR-240s to appear.

Over time, a few did make it into service, in the end however the process of standardizing production dragged along and it wasn’t until two years after its announcement that contracts could be let for production. By that time other technology improvements in voice radio communication had been discovered and it made more sense to shift to an even newer platform.

As a result the SCR-240 (a 12-volt system) and its partner the SCR-261 (a 24-volt system) were put out to pasture and a newer crystal controlled Command Set called the SCR-522 was designated as the new standard, and began to enter service. [4]

The Navy on the other hand, wanted a design of their own that appears to have been based on developments made by a Dr. Frederick H. Drake, the Chief Designer at the Aircraft Radio Corporation of Boonton, New Jersey. A member of a company that worked in close partnership with the Signal Corps lab/research and development and/or production system, he may have been the first one to conceive of the idea of independent, miniaturized, modular, plug-in transmitters and superheterodyne receivers. Notes from various sources refer to his work having taken place during the winter of 1934, far before others began to promote the idea.

The Navy took a liking to the idea, and so the Signal Corps standardized a design from its own Aircraft Radio Laboratory (a different organization than the Aircraft Radio Corporation mentioned above) that was based on high-frequency models, and set this into production for Naval aircraft use. It was called the SCR-274-N (with the “N” standing for… what else: Nancy. Snicker, snicker.. actually, it stood for Navy). With little fanfare it became one of the most widely used Command Sets of the war.

Strangely, the Navy preferred the SCR-274-N (see picture below) over the SCR-522 because they thought it had better range. Reaching out to 150 miles, it may have met their needs in this area, but it still weighed in at seventy-five pounds, something the Army Air Corps would not stand for.

Production was awarded to the earlier mentioned Aircraft Radio Corporation, as well as the Colonial Radio Corporation and Western Electric. Western Electric, not one to sit on its laurels and count its war profits, built over 100,000 of them by the end of 1944. By the end of the war over 1 million were built by the various contractors.

At this point radio development and design for WWII pretty much came to an end. Certainly, within the Signal Corps’ lab system research continued and improvements were found and made, but few of these resulted in new Command Sets being introduced to the field. One in particular that looked promising was a unit designated as the SCR-264. It was intended to move radio usage into the very high frequency (VHF) range, and while it was given a designation of its own, only a few made it into use. Nevertheless, as one can easily see from the “6” in its designation, later day historians would end up swearing that it had to have come before the SCR-274 mentioned above. Well, it didn’t. It came later, introduced a new VHF approach to Command Communications, but barely made it into production and/or use.

As an aside, it’s this latter point that makes the SCR-264 an interesting facet to WWII radio equipment sets… that is, it introduced use of the VHF ranges. As far as the Signal Corps was concerned, this was a necessary step that would have to be made, whether then, or after the war, as the high frequency ranges were simply too crowded for continued use, and so it was necessary to find ways to move up into the then nearly untapped very high frequency range.

Radio Direction Finding

In the end, the Command Sets (again, designed for short range use) and their associated Liaison Sets (again, developed for long-range use) not only met the needs of WWII, but set the U.S. out in front of the rest of the world. Even so, the Signal Corps’ development efforts were not over, for along with improvements in radio voice and code communication came the obvious knowledge that literally dozens of peripheral areas in warfare could be improved upon by taking the basic technology involved in radio sets and extending it into these areas.

What areas did this peripheral environment include? Two examples will suffice: radio compasses and radio navigation equipment.

Radio navigation began in World War I when radio direction finding was introduced. The basic technology involved soon began to be used in two similar but divergent areas, and these were developed further by the Signal Corps during the years between the wars.

The first was for the collection of signals intelligence, to locate enemy radio stations. The second dealt with looking at a transmitting radio station from a different direction… from the direction of using it to help in navigating to it. As a means to help both ships and planes navigate from one place to another, radio stations, or beacons, held great potential; and so it was this second area that the Signal Corps focused on.

In particular, they worked to develop both the radio compass, which would be used inside the airplane itself, and the navigational aids that they would “communicate with” on the ground. As we all know by now, this resulted in an instrument panel device in the form of an airborne compass that, while it looked like the well known magnetic compass, was not homing in on the North Pole but the ground transmitter it was tuned to.

On the radio navigation side, to support this form of communication a unit designated as the SCR-242 was developed. In the case of the Navy the capabilities of the SCR-274-N were expanded to include both short range voice and RDF, accomplished by adding multiple transmitters and receivers.

Each individual SCR-274-N in-aircraft transmitter or receiver weighed in the range of 6 pounds, and thus by itself was relatively light in weight, while the entire assembly could top 75 pounds. Unfortunately, back in those days when you sacrificed weight you also sacrificed capability. The result was that the radio navigation equipment’s transmitting signal strength was weak. One need only think of Amelia Earhart plaintively sending out weak signals as she searched for Howland Island to see this phenomena in action.

To make up for this lack of signal strength, ground navigational radio receiver sets had to be built to be able to detect these weak signals. This meant that while the radio navigation equipment in the aircraft was light, the stuff on the ground was big, bulky and heavy. The ground set that the Signal Corps standardized on at that time was the one they developed for the Navy. A cumbersome apparatus mounted on a tower, it employed a large H-shaped Adcock antenna. Lack of adequate power at most receiver station locations meant that the Adcock antenna had to be rotated by hand, to search for incoming aircraft. Notwithstanding this excellent solution to the need for better aircraft navigation equipment, when it came to the SCR-274-N, it was put into only limited service.

All of these things… from radio compasses to radio beacons, radio ranges, and other types of navigational equipment, eventually led to the development of instrument landing systems. Without them, today the global commercial airline system we all know and hate for its terrible service would not exist… another example of how the U.S. Army Signal Corps' work between the wars changed the world.

With instrument landing systems pilots who were otherwise blind during low visibility weather or light conditions could line up precisely with an airstrip and control their decent down a glide path… yet another term introduced to the world by the Signal Corps… to safely land. The equipment had to be accurate beyond measure, as well as highly mobile so that it could be shifted from one runway to another as winds changed.

To answer these needs, the Signal Corps’ Aircraft Radio Laboratory began work on finding ways to improve upon earlier forms of this equipment, with a particular focus on improvements on the detection of and locking onto the angle of descent, as well as means for detecting and controlling aircraft deviations to the right or left.

Microwave transmission held the most promise in this area, but unfortunately due to budget constraints and other factors development along this route could not proceed until the Signal Corps’ program for design and development was approved by the National Academy of Sciences. Since it proved impossible for the Signal Corps to convince the Academy of the urgency of their making a decision, this route was abandoned and the Signal Corps and its prodigy the Army Air Corps elected instead to go with a commercial Sperry Gyroscope system developed in collaboration with Stanford University and MIT (Massachusetts Institute of Technology).

In the end, the various branches of service got what they needed, although as the between-the-wars period morphed into the middle-to-late WWII period, more and more influence was placed on Signal Corps decisions by outside forces, including the Signal Corps’ sister service chiefs.

While we have provided an overview here of the Signal Corps’ efforts to develop both air and ground communication systems, primarily for “heavy” tactical use rather than for use in light, mobile, lower-echelon environments, the reader should remember that communication demands fell upon these areas too; and it was the Signal Corps that addressed them. For example, it was in this area that the sets many of today’s Signal Corps officers are familiar with can be found. The vehicular radios SCR-193 and SCR-245, the first walkie-talkie SCR-194 and its protégé SCR-195, and the SCR-197, which proved to be the last long-range ground set before the introduction of coupling range to motion communication. So too could be found the Signal Corps’ early frequency modulation (FM) units, like the SCR-293 and SCR-294.

These light tactical mobile systems aside, in the end as regards radio much of the credit for the development of Command Sets and Liaison Sets between the wars could still be tied back to the original SCR-187 and SCR-287 sets. These two systems provided the foundation of everything that followed.

- - - - -

Let us summarize what these three articles have taught us to date:

●  Having started in Part I of this series with a look at how the Signal Corps reorganized itself at the end of WWI to focus on instituting sweeping changes across all military services, as well as important sectors of America’s civil industry… changes that would allow the United States to leapfrog all other nations in everything from research to design, development, manufacture, quality control, and logistics management… for the purpose of developing next generation combat systems… and therein set the pattern for America becoming the greatest nation on earth,

●  And in Part II proving the Signal Corps' claim to this honor by looking at the specifics of how these organizational and institutional changes worked to take the lowest common denominator of communication at that time: wire based communication, and make it the reliable, dominant system it proved to be in WWI,

●  And then in this, Part III, extended our analysis up the communication food chain to radio communication… again as a means to show that the Signal Corps’ focus on improving the nation’s methods of research, design, development, manufacture, quality control, and logistics management was the primary cause that catapulted America to the head of the pack as a global powerhouse, it is only fitting that we end with an analsys one of the most important Signal Corps developments of all time: radar.

In Part 4 join us again, when we will finish this four part analysis of the Signal Corps’s efforts between the wars by looking at radar.   

             

Footnotes

[1] The 179 was originally designed for early use by the Cavalry, and thus was horse transportable: - To return to your place in the text click here:

[2] Variously:

(1) Signal Corps Information Letter, Nos. 1-16 (April, 1934-January, 1938), passim under Development of Equipment.

(2) SCL, Annual Report, 1941, p. 71.

(3) R&D history cited in Vol. VIII, Pt. 3, Projs (823) 10-11, 833-A.

(4) C&E Cases No. 3, Purchase of 1500 Additional SCR-288 Radio Sets, 15 Nov 41; No. 6, Substitution of Radio Set SCR-284 for Radio Set SCR-290 for the Coast Artillery Corps, 14 Nov 41; No. 55, Tab D, Signal Equipment Suitable for Standardization Within and Between Corresponding U.S. Army and British Commonwealth Army Units, 18 Nov 42. SigC Files.

(5) TM 11-227, Radio Communication Equipment, 10 Apr 44, passim.

(6) Interview cited in SigC Hist Sec with Capt W. W. Van Winkle (formerly assigned with com systems in Panama), Signal Corps Sidelights, Vol. I, Pt. 1, pp. 222-26. SigC Hist Sec File.

(7) CSigO, Annual Report, 1945, p. 398.

(8) History of the Philadelphia Signal Corps Procurement District, III, 627 ff. SigC Hist Sec File. - To return to your place in the text click here:

[3] Reference source for B-17 communication equipment facts: Radio Boulevard Western Historic Radio Museum  - To return to your place in the text click here:

[4]  Picture of SCR-522 courtesy Military Wireless in the Midlands Museum.  - To return to your place in the text click here:

Additional Sources

The picture showing Radio Row is courtesy The Electric Radio.

Additional general information gathered from Signal Corps Technical Letters: No. 38 (January, 1945), p. 24.

 

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This page originally posted 1 September 2013