AN/PRC-25

Radio, telefonia , telegrafia y equipos de transmision y recepcion, utilizados en los vehiculos militares

Moderador: administrador

AN/PRC-25

Notapor Patman » 21 Ene 2012, 12:42

Todavia no hemos abierto un thread sobre esta radio? busque y no encontre nada. Tambien puede ser que mi alzhaimer esta avanzando....

La PRC-25 (pric25) fue la primer radio exitosa usada en la Guerra de Vietnam. Tambien podemos decir que es la radio mas vista en films y fotos de la guerra. Se podria decir que no se puede hacer una pelicula de esa guerra sin que aparezca una pric25.

http://www.prc68.com/I/PRC25.shtml

Es una radio mochila que opera en VHF Banda baja y usada a nivel peloton. Cubre de 30.00 a 75.95 MHz en pasos de 50 KHz.
Las versiones vehiculares son la AN/VRC-53, AN/VRC-64, AN/GRG-125, AN/GRC-160
El manual es el TM 11-5820-498-12, -20P, -34P, -35

La RT-505/PRC-25 usa componentes modulares.

Es la primer radio que usa un tono de 150 Hz para abrir el squelch.

La radio tiene dos perillas para cambiar la frecuencia (una para los MHz y la otra para los KHz). Esta dividida en dos bandas, la alta y la baja.

La potencia va de los 1,5 W a 2 W de salida.

Puede ser usada con una antena corta o con la antena de 7 elementos de 3 mts. Tambien hay una antena tipo hilo largo (Eduardo K tiene un ejemplar).

Esta radio tiene una sola valvula de salida, por lo que la bateria entrega 14,4 V y 3 V.

La pric25 fue reemplazada por la pric77. Identicas exteriormente, la 77 no tiene la valvula por lo que su bateria solo entrega 14,4 V.

Tiene dos conectores U-229 de 5 contactos en el frente. Puede usar el handset H-138, el H-189, el H-250 (todos desarrollados en los 60's, aunque el mas usado fue el H-189).
El H-138 y el H-250 tienen contramicrofono para cancelar ruidos y dejar que la voz del radiooperador se escuche mejor.

Imagen
Patricio
LW8DBP
Avatar de Usuario
Patman
 
Mensajes: 1832
Registrado: 17 Jun 2009, 15:15
Ubicación: Miami, Florida - USA
Gracias dadas: 0
Gracias recibidas: 15

Notapor Patman » 21 Ene 2012, 13:12

Me acorde de la pric25 porque en History Channel estan pasando un documental sobre Vietnam y esta radio aparece constantemente.

Como dato interesante a investigar: el locutor menciona que en la WWII un soldado combatia promedio 10 dias durante su servicio mientras que en Vietnam el promedio era de 230 dias. Si esto es asi, que diferencia, no?

Este es un link a un articulo en ingles sobre la historia de la PRC-25.
Vale la pena leerlo:

http://www.fernblatt.net/prc25legend.html
PRC-25 la leyenda olvidada.
Patricio
LW8DBP
Avatar de Usuario
Patman
 
Mensajes: 1832
Registrado: 17 Jun 2009, 15:15
Ubicación: Miami, Florida - USA
Gracias dadas: 0
Gracias recibidas: 15

Notapor Patman » 21 Ene 2012, 13:23

Imagen

Mi pric25 con un H-250 handset

Imagen

PRC-25 con un H-138 handset

Imagen
En esta foto se puede ver que la PRC-25 es un primer modelo o prototipo. Vean las manijas que son diferentes y el lateral (al lado de la bolsa de antena) tiene relieve.
Patricio
LW8DBP
Avatar de Usuario
Patman
 
Mensajes: 1832
Registrado: 17 Jun 2009, 15:15
Ubicación: Miami, Florida - USA
Gracias dadas: 0
Gracias recibidas: 15

Notapor martinelterrible » 21 Ene 2012, 18:31

Pat hubo temas que se borraron vaya a saber por que,yo en su momento subi de la prc 25 que te cambalache,y no esta mas el tema,tambien desaparecio lo concerniente a binoculares,y a algunos wireless set por lo que vi....

un abrazo
Martin
Socio n°130
ZUNDAPP KS600
CMP C15
MB 43
CARRIER T 16
Avatar de Usuario
martinelterrible
 
Mensajes: 5973
Registrado: 25 Mar 2010, 22:27
Ubicación: Bajos de la Fragata Francesa
Gracias dadas: 92
Gracias recibidas: 131

Notapor martinelterrible » 21 Ene 2012, 18:34

por lo que vi en g-503,lo subi el 12 de mayo del 2010.....misterios de la web....
Martin
Socio n°130
ZUNDAPP KS600
CMP C15
MB 43
CARRIER T 16
Avatar de Usuario
martinelterrible
 
Mensajes: 5973
Registrado: 25 Mar 2010, 22:27
Ubicación: Bajos de la Fragata Francesa
Gracias dadas: 92
Gracias recibidas: 131

Notapor Patman » 21 Ene 2012, 20:38

Era raro que no hubiesemos posteado nada.
Bueno habra que volver a armar este thread.
La pric 25 es un eslabon importante en el desarrollo de la radio mochila tactica.

Pat
Patricio
LW8DBP
Avatar de Usuario
Patman
 
Mensajes: 1832
Registrado: 17 Jun 2009, 15:15
Ubicación: Miami, Florida - USA
Gracias dadas: 0
Gracias recibidas: 15

Notapor m606paz » 21 Ene 2012, 23:32

martinelterrible escribió:Pat hubo temas que se borraron vaya a saber por que,yo en su momento subi de la prc 25 que te cambalache,y no esta mas el tema,tambien desaparecio lo concerniente a binoculares,y a algunos wireless set por lo que vi....

un abrazo


Amigos

Estuve estudiando el tema y efectivamente se han perdido post, no solo de la parte radios sino de otras secciones.

Le vamos a enviar un mail al Hosting para ver que responden al respecto.
Tambien recordaran hemos tenido el foro fuera de servicio a veces por pocas horas y hasta una semana.

Verificando mails encuentro uno del 16 de Mayo del 2010, donde le comento a Christian que estabamos sin acceso al foro y pagina web hacia 24 horas y el Hosting le respondia que estan cambiando de servidor.

Puede suceder que al hacer backups y hacer una reinstalacion algo se pierda. Recuerdo que cuando G503.com cambio de version de foro y de servidor, muchos Post se perdieron, lamentablemente.

De todas maneras les agradesco su preocupacion y la voluntad y esfuerzo de volver a armar un post perdido.

Saludos :wink:
Mariano Paz
Socio n°27
1967 M606
1952 M100 Trailer
1944 Ariel WNG
LU4ALM
Avatar de Usuario
m606paz
 
Mensajes: 15637
Registrado: 16 Abr 2009, 17:33
Ubicación: Berazategui, Buenos Aires
Gracias dadas: 986
Gracias recibidas: 411

Notapor Patman » 28 Ene 2012, 11:11

Copio el articulo de Dennis Starks para no tener que ir a su link.

PRC-25, FORGOTTEN LEGEND; Part I, By Dennis Starks
Forward,

- I've title this article "Forgotten Legend" because in the past few years the significance of the PRC-25 has been overshadowed by it's more famous successor, the PRC-77 which in fact is only a slightly updated version of the PRC-25. Fledgling collectors today when searching for their next acquisition often ask/advertize for a PRC-77, when offered a PRC-25 they either stick their nose's up, or admit that they don't know what a PRC-25 is. At best they will acknowledge the PRC-25 but will only accept one as a last resort in the event they are unable to locate a PRC-77.

- It is true that the PRC-77 would become the most prolific tactical military radio of it's type in history, but it was the PRC-25 that was the milestone which got the ball rolling. And while the PRC-77 had been long established in the field, thousands of PRC-25's remained in front line service for at least another 20 years after the PRC-77's introduction. Still today, many thousands of PRC-25's lay dormant in various military storage facilities the world over. In my mind, the histories of the PRC-25 and PRC-77 are synonymous, and should never be separated.

In The Beginning,

- Our story starts not with the development of the PRC-25, but ten years earlier(yes, only ten years) with the introduction of the SCR-300(BC-1000). The very first VHF FM, front line tactical transceiver ever devised capable of operation while being carried by it's operator. Though it's VHF/FM mode would be received with great scepticism by the world, even in it's country of origin, it would instantly prove it's value under fire. It would set the stage for all such radios to come. Even today's most advanced hand held radios owe their existence to the success of the SCR-300 of 55 years ago.

- Even with the immense success of the SCR-300 which remained a standard issue item for another 10 years in the U.S., and it's allies for at least 15 years, the idea of a more advanced replacement began almost immediately after it's introduction. The rapid advance of technology during WW-II had produced subminiature tubes that could greatly reduce the size and weight of such a field radio. Along with this significant reduction in size and weight could be included greater reliability, simpler operation, greater frequency coverage and stability, reduction of the required FM bandwidth resulting in more channel capacity for a given frequency range, and a great increase in the ease of field servicing.

- By at least 1947 wood "concept" mock-ups of this new generation of radios had been constructed that would almost duplicate the final product. By at least 1950 functioning prototypes had been completed and possibly even an initial order for production radio sets. By 1951 production radios began to filter into the field, and by 1953, the PRC-10 family of radios(including the PRC-8 & PRC-9) had become familiar equipment. They would accomplish all those goals that had been established for the replacement of the SCR-300, and even include some additional "First" in the area of front line tactical communications equipment. These "first" included modular construction which allowed for almost instant repair-ability in the field by personnel with a minimum of training and support equipment. Secondly was the use of the now familiar short "Tape" antenna which has yet to see a viable substitute design after 50 years(prototype PRC-10's used a sectional antenna similar to the BC-1000 which was a British.design). The only thing to remain of the old SCR-300 was it's multi section, collapsible, long "whip" antenna, but now supplied with a rubber coated spring base to prevent damage while in use(another innovation left over from WW-II that is still in use today).

- But even before the PRC-10 had become established in the field, just as with the SCR-300 before it, plans had been initiated for it's replacement. 1949 saw the introduction of the transistor, and with that, a clamor by military planners to find practical applications for it's use. So in 1952, the criteria were set for our newest generation of solid state radios, and development contracts made. Included in these initial development contracts were the requirements for the PRC-25, PRC-35, and the new generation of solid state vehicular systems based on the VRC-12. Of these 1952 beginnings, the VRC-12, and the PRC-25(in the form of a PRC-77 and a multitude of clones) still survive today. The PRC-35, though a viable radio intended to replace the PRC-6, failed to find a niche in military applications that could not be filled by either the PRC-25, or the new squad radios (PRT-4 & PRR-9 which existed on separate developmental contracts). Thus it's great expense could not be justified.
Patricio
LW8DBP
Avatar de Usuario
Patman
 
Mensajes: 1832
Registrado: 17 Jun 2009, 15:15
Ubicación: Miami, Florida - USA
Gracias dadas: 0
Gracias recibidas: 15

Notapor Patman » 28 Ene 2012, 11:16

The PRC-25,(From Ref. #3)

PRC-25/RT-505; First solid state FM, tactical backpack transceiver, also first to use the now standard 150cps tone squelch system.

- Intended to replace PRC-8's, 9's & 10's inclusive. Development started 1958(XC-1) progressing through 1961(XC-3). Experimental versions(XC-1 & XC-2) had continuously tunable auxiliary receivers,this feature was omitted in the final variants adopted in 1961.

- Interring service 1962, very few were fielded till 1964.In 1965 the PRC-25 was officially replaced by the PRC-77 though it remained in first line service till the early 80's & many still remain in strategic reserves today.

- Ops 30-75.95mc, on any 2 preset synthesized channels of 920 spaced 50kc apart.RF power output is rated at 2 watts, actual measured output averages 4 watts. Radio can be used vehicular with the addition of the AM-2060 amplifier/power supply(several other types avail), see VRC-53 & GRC-125 for more info.Requires 3v & 12-15v normally supplied by BA-4386(many battery types exist). Size (RT-505 less battery box) 4 x 11 x 11", 13.5lbs.

- Numerous accessories were/are produced for the PRC-25/77 family to help it fulfil many roles, the major ones are AT-892(short tape antenna), AT-271 & AB-591(long antenna & rubber spring base), AT-912 or AS-1729(vehicular antennas), AT-984(longwire antenna, RC-292(fixed station antenna), AT-784(homing antenna), ST-138(backpack harness), CY-2562(battery box), H-138 or H-189(handsets), CW-503(canvas antenna & accessories bag).

- Over 130,000 set's were manufactured by more than 15 different (domestic) suppliers before production ceased. Ref.#9,#10,#11,#18,#23,#30

PRC-25A; Identical the PRC-25 except for modifications to the A25 module increasing the audio band-width. This to allow operation with TTY & voice security equipment. Ref.#26

PRC-25B; Identical to previous versions of the PRC-25. Suspect that these are overhauled radios & some may have been painted CARC. Also a possibility of the substitution of silicone type solid state devices. Ref.#26

PRC-25, FORGOTTEN LEGEND; Part II By Dennis Starks

The PRC-25 is Born,

- As noted in the first part of this story. Development contracts for the PRC-25 family of equipment were first let with RCA in or about 1952. We are unsure just when the first prototypes might have been produced, but the first hand-built operational versions appeared in approx 1957. These first radios shared only a passing resemblance to those we now know so well. They had the same basic size and shape, but the control panel lay out was completely different, and these controls had not yet been simplified to the point that the radio was operable by the run of the mil average grunt(one feature that would aids it's future great success). The internal design too was completely different from that of the final version. These first prototypes had not yet incorporated an internal power supply to produce the 135v plate voltage needed for the RF output tube(the radio's only tube). Instead, this voltage was derived from the battery just as with earlier tube type radios. A practice that just would not do, and in fact would have left these radio with a problem that had become notorious with it's predecessors.

- Only three experimental versions of the PRC-25 are known to have been built, the PRC-25(XC-1), (XC-2, and (XC-3). Both the XC-1(approx 1957), and XC-2(approx 1958) appear to have been cosmetically identical, and the XC-2 version even used the same case & chassis of the XC-1. But there is a major difference in the apparent direction that the designers would then take.

The XC-1, had an over complicated control panel. This in part was due to the fact that it incorporated what might have seemed a very attractive feature to us, but in practicality, was of little use for a radio of it's intended purpose. This was a built in auxiliary receiver that could be operated completely independent of the radios basic transceiver. This receiver was continuously tunable over the same range as the transceiver, and included a mechanical digital, veeder root type, counter for the front panel frequency display.

- The auxiliary receiver was eliminated in the XC-2 version. It's modules were simply removed, and all associated front panel control markings were just blacked out with paint. Other than the auxiliary receiver feature, these two early versions do not appear to have any other differences.

- It would seem that at mid-development, the designers of the PRC-25 made a radical change in direction towards their goal. Their philosophy on just what the ultimate front line combat radio would be changed dramatically from one of "ultimate versatility", to one of "ultimate simplicity". Was this a simple cost reduction ploy? Possibly, the projected cost of the PRC-25 was VERY high. Or was the plan intentional to make the operation of the PRC-25 as simple as possible regardless of cost? History will show that the choices made, for whatever reason, were the correct ones!

- Besides those things already detailed, the XC-2 still had a couple problems. The high voltage battery had not yet been eliminated, and the control count/complexity was still too high even with the auxiliary receiver removed. The total control count had only been reduced by one, and the positions had only been reduced from 13 of the XC-1, to 10 of the XC-2. By 1960 all these problems would be reduced to a minimum, or eleminated as the PRC-25(XC-3) would be completed for testing. The early high voltage, multi section battery was eliminated by incorperating an internal inverter type power supply to provide the needed plate voltage for the radio's only tube. This from a common low voltage source of 12vdc. The front panel control count had been reduced from 6(& 10 positions) of the XC-2, to 5 controls with 8 positions. Now the radio was simple enough that anybody, regardless of their familiarity with radio, could operate it.

- The radio's only tube(used in the RF output) had not yet been replaced because technology hadn't provided a solid state device capable of yielding the needed power level. This tube(2DF4), though still a draw back, had been specially designed to be extremely efficient, and rugged. It was instant heating so It, and it's associated power supply, only came on when the transmitter was keyed thus reducing excess power consumption to an insignificant level. Though only rated for an output power of 2 watts, 3-4 watts are the norm. In all my years of tinkering with PRC-25's, I have never seen a bad 2DF4! And believe me, I have abused them, possibly more so in civilian life than I did in the military.

The PRC-25, "Milestone Radio",

- Like it's grandfather the SCR-300, the number of innovations the PRC-25 included are many, and extremely significant. So much so that communications doctrine, and designs, would be changed forever. This earning it the title of "Milestone" radio just as it's grandfather did 23 years before

- It's RF power output was more than twice that of any previous radio of it's type. Greatly increasing communications range, and reliability.

- It was the first "solid-state" radio of it's type, even pre-dateing the relativily simple PRT-4 and PRR-9. Providing for the utmost in field reliability, minimal maintinance, and power consumption.

- It's battery was a simple, small, and inexpensive 12v/3v type which would provide at least the same operational time of it's predecessor at one fourth the size. This not only eliminated the extremely expensive, and dangerously unreliable multi cell/high voltage types but also allowed it's operator to carry along several extra batteries without burden.

- It was the first synthesized radio ever built. This eliminated the complications and difficulty in frequency change that normally required a trained and competent operator. The frequency drift inherent in all it's predecessors had been eliminated, and this new stability allowed for a narrower band width that in turn provided a greater channel capacity for a given frequency range(channel spacing was more than cut in half, from 100kc or 200kc of older radios to 50kc of the new generation). The later was so significant that almost two sections of the previously used VHF spectrum would be abandoned in favor of the more reliable, and less noisy upper portion alone. Thus, this new radio, though at first seemingly expensive, could alone replace more than three systems currently in place, reducing overall communications cost, and field logistical support problems.(Previously, Infantry, Armor, and Artillery all used separate sections of the spectrum between 20-54mc which included their separate associated radios. Now, all these contingents could use the same frequency range of 30-76mc, and the same radio.)

- It was the first radio ever to use the 150cps tone squelch system which would become the world military standard. This completely eliminated operator error in squelch adjustment. No longer would constant re-adjustments in squelch be needed to compensate for a changing ambient noise level. Accidental squelch changes by bumping exposed controls were greatly reduced, or eliminated. Any of these older traits might have resulted in not receiving vital traffic. The least of the advantages this new system offered was a reduction in front panel control count, and a significant step in the direction of operability by any untrained soldier.

- It was the first radio to use as standard, a "low" impedance dynamic(magnetic) type mic element in leu of the old carbon types. The later was extremely temperature and water sensitive, if it got wet, or damp, it was destroyed, not a good idea in a tropical environment. Or if it got extremely cold, the carbon activity would slow, so no good in the snow either! The old carbon types were also notoriously insensitive especially if they had a physically small element(cartridge), it was often required for an operator to yell, point-blank into one for it to pick up his voice, again, not a good idea in combat. Not only did this new mic type have superior survivability, and sensitivity, but's it's low impedance allowed for long lengths of audio cable without fear of hum or interference pick-up. The low impedance dynamic mic would go on to be the type of choice for nearly every kind of microphone application, military & civilian.

- The new generation of radios would abandon all old audio connector types for a much smaller, and simpler one(U-77/old, U-229/new). It's small size would allow for reduced front panel congestion. So much so that two audio connections could be provided instead of just one. These connectors are still the world standard today, surviving in service longer than any other standard type in history.

- It's physical design was unlike any before it. It's extremely rugged construction could(as I have witnessed) survive being run over by the proverbial "tank"! It could be submerged in water at a depth of 6 feet for an hour with no ill effects. In all, the PRC-25 was built to survive, and it's construction/design has yet to be surpassed.

- The host of accessories developed for this radio are astounding. They would allow it to serve in numerous and diverse capacities for which it had never been intended. So great is the number that it is impossible to list even a fraction of them. And while some might think the PRC-25 to be militarily extinct, it's accessories form the foundations for all such radios produced today. They all use audio accessories, antennas(both portable and vehicular), power supply/amplifiers, mounts, batteries, carry equipment, etc that were either originally designed for, or derived directly from, those built first for the PRC-25. If they don't actually use PRC-25 equipment, they all will at least use the same connectors, have the same threads, have the same dimensions, or fit the same foot-print, and will be functionally interchangeable with those of the PRC-25. This after over 38 years, and our transition from Germanium transitors and high power miniature VHF RF tubes(2 watts), to the use of LSI IC's each containing thousands of transistors, and RF transistors capable of 50 watts or more smaller than a postage stamp. I think this is quite a testament!

- The PRC-25 was as ready as the state of the art in technology would allow. So in 1961, the PRC-25(XC-3) was officially adopted as the AN/PRC-25(RT-505). But for whatever reason, it would not be for another three years that it would begin to make it's contribution to history. But when it did, it did so in a BIG way! It would become the most used, and copied radio in military history. Still today, "after 38 years", it remains the standard by which all new designs are compared, and for which complete compatibility must be maintained.

Imagen
aca se puede apreciar la diferencia de tamaño entre la BC-1000 y la prc-25
Patricio
LW8DBP
Avatar de Usuario
Patman
 
Mensajes: 1832
Registrado: 17 Jun 2009, 15:15
Ubicación: Miami, Florida - USA
Gracias dadas: 0
Gracias recibidas: 15

Notapor Patman » 28 Ene 2012, 11:25

PRC-25, FORGOTTEN LEGEND; Part III, By Dennis Starks

The Legend Begins(1965-1970),

This chapter in the PRC-25's lengthy saga has taken several forms. None seemed to do it the justice it deserves. So I've decided to take a "time-line" approach to it's "Legend". I believe this will make it much simpler for the reader to follow it's progression, and judge it's impact on history.

1952,

Requirements for the new generation of PRC-25 family of equipment are laid down.

1954,

Development contracts with RCA are let.

1957,

The PRC-25(XC-1) appears.

1958,

The PRC-25(XC-2) appears.

1959,

The PRC-25(XC-3) appears early in the year.

1960,

November, Two modified PRC-25(XC-3) prototypes are tested.

In June, the VRC-12 is adopted as a standard issue item of equipment.

1961,

Though the PRC-25 had been officially adopted in May(after two years of testing and refining the final version), for some reason it would not be put into full scale production for another four years.This four year delay in production might be explained later, but by 1965 there would exist a dire need for these radios that surpassed any higher echelon excuses. October of this year saw an initial contract for production units with RCA.

1962,

December, deleveries begin of production PRC-25's.

1963,

In August, initial shipments, and distribution to U.S. forces in Europe begin. Europe had become our traditional test arena for equipment of all types some years before.

1964,

Testing of the PRC-25 family of equipment, including the VRC-12(which had been adopted one year before the PRC-25), had been completed in South Vietnam. A few of the sets were tested by signal advisers who had concluded it was a significant improvement over the older PRC-10's. Despite their favorable conclusions, they were unable to obtain approval for it's adoption as the standard adviser radio. This was due in part to the extreme cost of the radios, and the lack of logistic support in place. Late in the year, 500 PRC-10's are dispatched to South Vietnam as an emergency measure for use by advisers.

1965,

By now only token quantities of the PRC-25 existed which had no doubt been built for the purpose of field trials. When combat troops began to deploy to South Vietnam in the Spring, they were supplied with the same early generation of equipment that the adviser groups before them had been, the PRC-10. Yes, the PRC-10, it was used extensively by all those involved, enemy & allied alike until the late 60's(much later than generally believed by most people).

- In the summer, the limitations of the PRC-10 began to result in excessive combat casualties with the Marines, and the 173d Airborne Brigade, General Westmoreland then issued an "urgent battlefield requirement" for 2000 of the new radios which had been tested in this theater the year before. The Signal Corps responded by shipping the entire stock of PRC-25's on hand(only 1000 sets which had been destined for Europe) and began emergency procurement for the remaining 1000 sets of the order. This initial 1000 new radio sets where in the hands of troops within a few weeks. Of the 2000 set order, 1500 would be received by advisers, and Special Forces, with the remaining 500 going to combat troops.

- An "X" mode requirement(speech security equipment) was added, to specifications for improvements to the PRC-25. This would eventually resulted in a re-designation of the radio to the PRC-77.(Special Note: it was not the redesign to eliminate the output tube that prompted this re-designation, nor the "X" mode requirement alone, it was a combination of all the refinements that would eventually warrant a re-designation to PRC-77)

1966,

"Operation Attleboro", In November, U.S. Forces(a small task force of the 196th Light Infantry Brigade) are prematurely drawn into the heavy jungle of War Zone C to ferret out Viet Cong storage depots. Instead, they stumble on to the head quarters of the notorious 9th Viet Cong Division who immediately surrounded the three company Task Force, cutting off all attempts at relief.

- Throughout the morning of the 4th, relief forces fought their way to the beleaguered task force. Using only a PRC-25, the task force commander, Maj. Guy S. Meloy, eventually controlled eleven companies from five separate battalions while lying pinned down by enemy fire. To aid this miraculous feat, Sfc. Ray Burdette had assemble a ground plane antenna(RC-292) and propped it up against a nearby tree. This for two days before pressure was relieved long enough to effect a withdraw of the battered task force. This was the first time that a large Viet Cong force stood and fought.

- The PRC-25 is now listed as a replacement for the PRC-9, and PRC-10 inclusive, in Australian tables for equipment(which also includes the PRC-64, -41, -47, -62, GRA-71, GRC-106, PRT-4 & PRR-9, and VRC-12 among others).

1967,

15,000 PRC-25's, and 7000 VRC-12's are now in the hands of U.S. troops, and another 9000 PRC-25's are being issued to the South Vietnamese Army. Issue to the South Vietnamese army had been purposely delayed to relieve frequency/traffic congestion.

- November, after the "Battle For Dak To" involving the 173d Airborne Brigade's 2d Division, and the 503 Infantry, against the 174th North Vietnamese Regiment atop Hill 875. Combat casualties for equipment alone were listed as 89ea PRC-25's, 22ea PRT-4's & 19ea PRR-9's(173d Airborne), and 32ea field telephones.(Note these were PRC-25's and not PRC-77's!)

- Combat loses of equipment for this year deplete the Army's entire inventory of tape antennas. As an emergency expedient 15,000 special bushings are fabricated to adapt the old PRC-10's antenna to the PRC-25.

- It is discovered that only half of the radio operators using the PRC-25 are Signalman, or have received any formal training. Most operators are found to be simple infantryman drafted to the radio operator position to replace fallen radioman. The simplicity of the PRC-25 is a great success. Because of this simplicity it is proposed to initiate PRC-25 training to "all" Army trainees, and not just signalman, this is an unprecedented act! Fall of this year saw the completion of testing of the newer PRC-77.

1968,

In May, shipments of PRC-77's began to Southeast Asia. They had been delayed due to deficiencies in the batteries for the KY-38 encryption equipment(because they could not vent, they were prone to explode), and for lack of a single capacitor which had been supplied by a subcontractor gone bankrupt. By December, 9000 sets where in the hands of U.S. troops.

- Theater commanders are unwilling to turn in their PRC-25's upon receipt of new PRC-77's. The PRC-25 had become "Too good, no one wanted to give them up!"

1969,

Those who believed the war was to be fought and won as a counterinsurgency rather than a conventional war, profess that the PRC-25 alone had far more utility than a B-52 and it's associated support, or any troposcatter or satellite terminal.

- In late December, infantryman overrun the camp of the highly successful Viet Cong A3 Technical Reconnaissance Unit. Among the equipment captured included 1400 hand written copies of intercepted Allied messages, 2ea PRC-25's, 1ea PRC-77, and 1ea Chinese R-139 receiver.

1970,

PRC-25's had become the primary targets for specially formed enemy units who entered battle with one mission, to capture these radios. In the beginning, the first priority for the issue of these sets went to Viet Cong units monitoring American traffic. By the early 70's, so many PRC-25's had been captured, or stolen, that it had become a standard issue item for most enemy line units.

1976,

- My first experience of many with a PRC-25(listening to Hispanic TV broadcast off the coast of Guantonimo). As of 1980, I had never seen a PRC-77.

PRC-25, FORGOTTEN LEGEND; Part IV, By Dennis Starks

Forward,

- By the early 1970's, the new PRC-77's had become hopelessly intermixed with the old PRC-25's among all the using armed forces(regardless of country). Those who still had PRC-25's in inventory refused to turn them in being convinced of their value under fire.. Confusion was now to the extent that all official reports, manuals, etc would use their designations interchangeable, as indeed the radios themselves were for all practical purposes. For this reason it now becomes near impossible to separated the exploits of the two different models of the same radio. So we'll continue this story with that of the successor to the PRC-25's 'Legacy', the 'Ultimate PRC-25', the 'PRC-77'.

PRC-25 Legacy,

- History repeats itself! Just as the replacement for the SCR-300 was conceived just as it was introduced, and the PRC-10 had been replaced on paper a year before it had even been established in the field. The first PRC-25's had been in effect replaced before they were born. From the very beginning certain requirements had been in place for it's final version. The first, and primary priority was the elimination of it's output tube resulting in a 100% solid state radio. This early goal was for the PRC-25, and was never intended to result in the PRC-77. But as we will see, the original plans were foiled.

- It would seem that while the PRC-25 had been officially adopted as Standard "A" in 1961, this might have only been an expedient means of relieving pressure on the development-infrastructure. Adoption, did not mean that the sets would then go into immediate large scale production(which it didn't), but it might provide a means of stalling for time while development continued, and prove an effective ploy for obtaining the funds needed for the purchase of limited-production units, and their continued field trials. Indeed, the evidence shows that all those who where familiar with the PRC-25 as of 1965 had been exposed to it as the result of these "Field Trials" being conducted as late as 1964, and.not because of it's issue to any as standard equipment.

- But this Adoption/Extended-Development tactic backfired when in 1965 General Westmoreland issued his "urgent battlefield requirement". As the PRC-25 had been officially adopted as "Standard A", the powers that were could now provide no excuse for not supplying the radios especially as they already had a small quantity in hand. So these trials were brought to an abrupt halt. The unfinished PRC-25 being forced into an early, and hasty mass production by a completely unprepared industry. It would arrive In-Country with virtually no support structure, as one had not yet been established.

- Further development must then, out of necessity, take place under fire from hostile forces in actual combat, as indeed it did. We might conclude then that the development of the PRC-25 was never completed, and the emergency of war forced it's use prematurely. The results of this trial-by-fire would be a radio set that would not see a competent rival for near 30 years.

- Regardless of the PRC-25's premature obligations to war, work towards the replacement of it's output tube continued. Inadequacies began to show up in combat that would in turn be added to the list of it's planned refinements. Most had to do with ancillary equipment such as handsets, batteries, support equipment and logistics. All were quickly remedied.

- But some real problems also surfaced. The first was interference when used in close proximity to other radios, both on receive and creating interference when transmitting. This previously unforeseen problem became apparent when trying to use two like radios back-to-back as a repeater under certain conditions. But it became intolerable when they were combined with dozens of other radios(some being much more powerful) at congested communications sites. All having their antennas mounted inches from each other on common, overcrowded, towers. So included in the PRC-25's refinement package where steps to reduce spurious emissions during transmit, and provide it's receiver with better selectivity.

- In 1965, just as all the problems were solved, and refinements thought to be completed(including the replacement of it's output tube), the Army threw a monkey wrench into the works. It added a requirement for compatibility with speech security equipment(X mode). This would result in a delay of two more years before the deployment of the ultimate PRC-25. These two years where added as the result of bureaucratic mistrust, and foot dragging, rather than any limitations in technology, or industry.

Birth of The Ultimate PRC-25,

- In 1965, the National Security Agency(that government body having jurisdiction over all encryption equipment, and methods) was asked to develop speech security equipment for tactical units. They were at first reluctant to produce cryptographic equipment for combat infantryman that would undoubtedly be captured. But by January 1966, the NSA would agree to develop the device for portable radios. The NSA and the U.S.Army Electronics Command then designed a new radio from "a modified PRC-25" that could connect to the new speech security equipment. X mode is born. The PRC-77 ?, Not yet !

- The new radio was in fact not "new" at all, it was simply a refined PRC-25! Again, the PRC-77 was not the result of successfully replacing the PRC-25's output tube, this had already been done. Nor was it the result of any other circuit or design changes. It was all these refinements combined, and when joined by the X mode ability, and the deciding factor that 10's of thousands of the earlier radios had already been fielded as the result of the emergency of war. A positive method of distinguishing between the two was now needed. A modified designation such as PRC-25"B" was simply no longer adequate. So now, (less than one year after PRC-25's were first deployed to Vietnam),.the PRC-77 is born! If General Westmoreland's "urgent requirement" had been delayed only a couple of months, there might never have been a need for the designation of PRC-77 affixed to the radio that received it!

- By the fall of 1967 the PRC-77 was still not yet available. Not at all because of any deficiencies in the radio, or protracted development time. All problems had been worked out long before(PRC-25), all testing had been completed, the PRC-77 was in production, the radio was ready! It was again NSA foot dragging, combined with minor problems with the new encryption equipment, that would delay deployment of the PRC-77 till May of 1968. By December, 9000 new radios would finally be in the hands of the troops.

- The new PRC-77 was externally identical to the PRC-25 in every respect. Without it's data tag in place, it is absolutely impossible to tell the difference between the two. Once opened up, only a trained eye can even tell the difference, and most of it's internal modules are interchangeable. But it did boast several improvements; it's receiver had been upgraded with better selectivity, it's transmitter's spurious emissions had been reduced, and of course, the output tube had been eliminated(though some sources will report an increase in RF output/range, any difference is minimal).

- Lastly, the radio's audio bandwidth had been widened to accommodate the new X mode requirement. This would eventually allow the fringe benefit of using various data modes. These modes included MCW*, TTY, and modern day Packet.

*(MCW was used by Australians who did not yet have access to the highly restricted U.S. voice encryption equipment. These devices were protected to the point of paranoia until the mid 70's. Neither had they developed systems of their own. MCW then was their only means of transmitting secure messages. This was accomplished by using an external tone oscillator, and CW key. The same method was also practiced by various para-military groups being supplied equipment by the CIA.)

PRC-25, FORGOTTEN LEGEND; Part V, By Dennis Starks

The PRC-25 Legacy Continues, The PRC-77,

- By the early 1970's, production of the PRC-25 had ceased. Over 130,000 radios had been built in the U.S. alone. Production had continued even after the advent and large scale deployment of the PRC-77. The PRC-25 had become legend, in the words of General Westmoreland himself, "the PRC-25 was the single most valuable contribution to the war effort". Not the M-16 rifle nor any other item of ordinance, but a lowly radio!

- Though designed for use at a platoon level, the circumstances of war and environmental conditions had made it the primary communications at every level from 10 men to 10,000. The PRC-25 had become the modern day quide-on, or flag, carried at the head of battle charges 100 years before. Just as 100 years before, the quide-on bearer was the primary target of an opposing force, but as he fell, the next soldier would gallantly take up the flag, and charge on. The simplicity of the PRC-25 allowed the same thing, should it's operator fall(as many, MANY, did!), the next soldier would snatch it up and carry on.(many surviving examples of the PRC-25 still retain their unit markings, not just numbers painted on them, but elaborately painted unit crest, or insignia). Even though the PRC-25 was still in the hands of troops, as it would be for many years to come, the Legacy is now carried on by it's slightly younger twin, the PRC-77.

- By 1973, the PRC-77 had been established the world over. It was being produced by at least four domestic manufacturers, and being distributed to at least 10 countries(some in kit form). Foreign companies had begun to build their own for both domestic use, and export. Known companies producing radios include RCA, Magnavox, E Systems, Cincinnati Electronics, Tadiran. Countries receiving radios included U.S., Germany, Spain, Norway, Korea, Iran, Jordan, Lebanon, Israel, Australia, and others. The average cost of the set is $1200.

- In the late 1970's, a viable radio for use at the squad level was finally introduced after 15 years of development, the PRC-68. It would start to make a dent in the needed quantities of PRC-77's as it would no longer be needed at this low level of the command structure.(Neither the PRC-25 nor -77 had ever been intended for use as a squad level radio. Lack of a viable radio, and the limitations of range in a dense jungle environment had forced them into this service).

- By 1980, E-System alone(a Johnny come lately) had delivered 25,000 sets to the U.S. military, and exported over 12,000. By 1985, they had delivered 40,000 to the U.S. military alone, and had exported equipment to 50 countries. In 1981, Sentinel Electronics was added to the list with a U.S. order of over 12,000 radios at a cost of $900 per radio. In 1983, another order was placed with Sentinel for $3 mil, and NAPCO was added as a supplier with $2.09 mil order. In 1984, C & G Associates was awarded a contract worth $1.84 mil for over 2000 radios. By 1986, Iran had begun exporting PRC-77's(six years after their disassociation with the U.S.). In 1989, Lucas Hazelton(AN/COMM) received a contract for $22 mil(the same year that the PRC-119 begins deployment). The above listed data is only the tip of the iceberg.

- By the mid 1980's, the success of the various generations of the PRC-68(including the PRC-126) had proved good enough that they could be used at higher levels than they had been intended, this too would reduce the quantities of PRC-77's needed in the field. Also by this time, there were many usurpers that claimed to be the successor to the vulnerable old PRC-77 both foreign and domestic. They would all prove false.

- Logic might suggest that with all these attacks on the domain of the PRC-77, it would begin a decline from the military seen, but the reverse is true. There were still not enough radios sets in service to meet the demand. Some units of the National Guard and Reserve had to resort to alternate equipment to meet their needs. Radios like the Trans-World PRC-1077 would appear in their inventories. Not because it had been adopted, or was an authorized replacement for the PRC-77, but because it was all they could get, and it had been approved for purchases.

- In 1987 the official successor to the PRC-77 was adopted, the PRC-119. It was grossly over complicated and required the constant attention of well trained operators and technicians. It's extremely complicated/sophisticated design required service personnel to make regular rounds of the units equipped with them to keep radios running. The supposed benefits of Singars, and frequency hopping were lost in the operators inability to set up or maintain these modes, and the radio's frequent failures.

- In 1990, Desert Storm, the U.S. military was sorrily lacking in field communications equipment to outfit it's hurriedly mobilized forces. There were not enough PRC-119's nor it's sister systems to go around. Again, the PRC-77 is put into action, and again there are not enough. Orders are placed with every company known to still produce the radios. Domestic production wasn't enough, and radios had to be imported from Israel, and Germany(VRC-12 systems were similarly acquired). Units that are issued the PRC-77 vice the PRC-119 don't yet realize how lucky they were.

- By 1992 it was estimated that over 500,000 radios had been built in the U.S. alone, and it was still in production for the U.S. Army as of 1994 by NAPCO(six years after the adoption and deployment of it's successor, the PRC-119). By the mid 1990's, units that had been issued their new PRC-119's, and had been forced to turned in their old PRC-77's were begging to get their old PRC-77's back. Experiences during Desert Storm, and after, had proved the new PRC-119 to be too complicated to be operable by the common soldier, and it's temperamental nature required constant servicing. The hard won lessons of Vietnam which had spelled the extreme success of the PRC-25 and -77 had been forgotten! The 40 year old proven philosophy of "ultimate simplicity" as apposed to "ultimate versatility" has yet to be re-learned.

- It's most impressive, that after 42 years, the story of the PRC-25, and the PRC-77 cannot be concluded, nor my account of it. Because they still serve on. Many thousands of PRC-25's still languish in storage awaiting a call to duty, or are used in a diminished capacity every day. And the PRC-77 is still in production(in one form or another), and still in use, all over the world. The age of some radios being nerely twice that of their operators!

- Here is a summary of the longest lived military radios(none would ever approach the production numbers or widespread use of the PRC-25 & -77):

Navy TCS, 1939 to approx 1969, 30 years.

BC-610, 1940 to 1969, 29 years.

Gibson Girl, 1942 to approx 1985, 43 years

VRC-12, 1960 to now, 39 years(and still going)

PRC-25 & PRC-77, 1961 to now, 38 years(and still going)



Dennis Starks; Collector/Historian

Midwest Military Communications Museum

email: military-radio-guy@juno.com
Patricio
LW8DBP
Avatar de Usuario
Patman
 
Mensajes: 1832
Registrado: 17 Jun 2009, 15:15
Ubicación: Miami, Florida - USA
Gracias dadas: 0
Gracias recibidas: 15

Notapor Patman » 28 Ene 2012, 11:30

Por lo que tengo entendido, el EA recibio solo PRC-25 y la Marina las PRC-77.
La mayoria de las PRC-25 estarian en algun regimiento de Mendoza.
Y el dato que recibi en el 2011 era que las querian volver al servicio por falta de insumos para las 3600 y 4600.

Habria que chequear esta info.

Imagen
otra foto para comparar tamaños.
Patricio
LW8DBP
Avatar de Usuario
Patman
 
Mensajes: 1832
Registrado: 17 Jun 2009, 15:15
Ubicación: Miami, Florida - USA
Gracias dadas: 0
Gracias recibidas: 15

Notapor Patman » 15 Sep 2012, 21:17

Mis dos PRC-25 salieron de lo de Aguirre. Luego de pasar un par de años visitandolo y llevandole fotos de esta radio para ver si la tenia vista, salieron a la luz. No podia creer lo que veían mis ojos. La radio tan buscada estaba ahi, y habian estado ahi por algun tiempo. Obviamente le pregunte porque nunca me habia dicho que tenia. Su respuesta fue: Si te vendia estas, no comprabas de los modelos anteriores (PRC-10).

Primero compre una y luego la otra. Ambas vinieron peladas, sin accesorios.
Aguirre me dio una copia del catalogo de Fair Radio Sales. Encargue los accesorios y pude completar los sets.

Hasta pude traerme para hacer una VRC-53 (o sea el adaptador para hacer la PRC-25 vehicular).

Ninguna de las dos radios trajo la chapita de identificacion. No se si se las sacaron para evitar que sean identificadas o por alguna otra razon.

Entre las cosas que le pedi a Fair Radio Sales, fueron las chapitas de identificacion y las tapitas para que no entre suciedad en la base de la antena.

En la era de Charly Surplus compre la funda para los accesorios. Y en un local que estaba por Palermo la base de la antena larga AB-591 (para la antena larga). Estos dos items antes de tener la radio.

Lo ultimo que compre en FRS fue el Headset H-161.

Y el otro dia encontre el H-138 de la misma marca que la radio (RCA).

Mi primer PRC-25 que todavia conservo es una radio manufacturada por Radio Corporation of America (RCA).

Y por lo que se ve en su interior, nunca fue tocada o reparada (por lo menos aca).

Los primeros prototipos de la PRC-25. X1 o X2, X3 y X4. Los primeros tres contaban con un receptor auxiliar en la misma radio. Cosa que luego descartaron.

Imagen
de arriba hacia abajo, X2, X3, X4.

Imagen
Una X3 en una configuracion vehicular y mochilar. Vean el handset H-33
Patricio
LW8DBP
Avatar de Usuario
Patman
 
Mensajes: 1832
Registrado: 17 Jun 2009, 15:15
Ubicación: Miami, Florida - USA
Gracias dadas: 0
Gracias recibidas: 15

Notapor Patman » 15 Sep 2012, 21:42

Imagen
Mi PRC-25 desarmada.

Imagen

Imagen

Imagen

Imagen
Vean la etiqueta entera!!!

Imagen

Imagen

Imagen

Todo RCA (menos la chapita de identificacion)
Patricio
LW8DBP
Avatar de Usuario
Patman
 
Mensajes: 1832
Registrado: 17 Jun 2009, 15:15
Ubicación: Miami, Florida - USA
Gracias dadas: 0
Gracias recibidas: 15

Notapor Patman » 15 Sep 2012, 21:46

La "PRIC" 25 en accion...

Imagen
Patricio
LW8DBP
Avatar de Usuario
Patman
 
Mensajes: 1832
Registrado: 17 Jun 2009, 15:15
Ubicación: Miami, Florida - USA
Gracias dadas: 0
Gracias recibidas: 15

Notapor Patman » 15 Sep 2012, 21:47

Bueno, en el fondo de casa.....

Imagen
Patricio
LW8DBP
Avatar de Usuario
Patman
 
Mensajes: 1832
Registrado: 17 Jun 2009, 15:15
Ubicación: Miami, Florida - USA
Gracias dadas: 0
Gracias recibidas: 15

Siguiente

Volver a Radios y Comunicaciones

¿Quién está conectado?

Usuarios navegando por este Foro: No hay usuarios registrados visitando el Foro y 4 invitados

cron