Fact-checked by Grok 2 weeks ago

SCR-536

The SCR-536, commonly known as the Handie-Talkie, was a pioneering hand-held transceiver developed for the U.S. Army during , marking the first portable wireless communication device designed specifically for infantry use in combat. Weighing approximately 5 pounds (2.3 kg) and powered by batteries, it integrated a , earphone, , and transmitter-receiver into a single compact unit, allowing one-handed operation via a push-to-talk button. Operating on (AM) in the high-frequency band of 3.5 to 6.0 MHz using crystal-controlled single-channel tuning, it provided a communication range of about 1 mile (1.6 km) over land or up to 3 miles (4.8 km) over water, though performance varied with terrain and conditions. The device was developed by a team at the Galvin Manufacturing Corporation (predecessor to ) under the leadership of engineer Donald Mitchell, who recognized the need for mobile radios after observing maneuvers in the late 1930s. Initial Army skepticism due to the limited range gave way to rapid production following U.S. entry into the war in 1941, with over 130,000 units manufactured by 1945 and first deployed during the 1942 Allied invasion of . It became standard issue for commanders, leaders, paratroopers, and crews across both and Pacific theaters, revolutionizing squad-level coordination by eliminating reliance on cumbersome wire-based systems like the EE-8 field phone. Despite its innovations, the SCR-536 had notable limitations, including short battery life of less than 24 hours, vulnerability to water damage, and a fragile 40-inch that often broke in rough handling—soldiers were even instructed in the manual to it with a or use it as an improvised . changes required disassembly and adjustments with plug-in crystals and coils, making it unsuitable for on-the-fly retuning in dynamic battlefields. Nonetheless, its success paved the way for postwar advancements in portable radios, influencing the development of (FM) models like the SCR-300 "" and modern handheld transceivers.

History

Development

The SCR-536, the first handheld , was invented in 1940 by Don Mitchell, chief engineer at Galvin Manufacturing Corporation—the predecessor to —under the leadership of Daniel E. Noble, in direct response to the U.S. Army ' demand for more portable communication equipment beyond vehicle-mounted systems. Mitchell's team, including engineers Ray Yoder, Jack Davis, and Paul Smith, drew inspiration from observing cumbersome backpack radios during exercises at Camp McCoy, , where Mitchell noted soldiers abandoning heavy gear in simulated combat scenarios. This initiative aligned with the Army's push for reliable, man-portable devices to enhance tactical coordination in fluid battlefield conditions. The primary design goals centered on creating a compact, battery-powered (AM) transceiver optimized for short-range voice communication among combat troops, developed alongside contemporary backpack models to provide a truly handheld option. Engineers aimed to integrate all essential components—microphone, earphone, batteries, , and transmitter—into a single, lightweight unit that soldiers could carry without encumbrance, prioritizing simplicity to enable rapid deployment by non-technical personnel. Early prototypes were developed and tested between 1940 and 1941, with a focus on ruggedness features such as water resistance to withstand harsh environments and intuitive controls, including a prominent push-to-talk , to ensure usability under by infantrymen lacking specialized radio training. These iterations, evolving through models designated A through F, underwent field evaluations to refine reliability for short-range operations, addressing the limitations of prior bulkier systems. In early 1941, the U.S. Army awarded Galvin Manufacturing an initial experimental contract for the device, recognizing its potential for airborne and ground troops, and this marked a pivotal transition in from bulky, team-dependent radios to truly personal handheld units.

Production and Deployment

Mass production of the SCR-536 began in July 1941 at the facilities of Galvin Manufacturing Company in , , following its development for the U.S. Army . By the end of , approximately 130,000 units had been produced, primarily by Galvin (later known as ), with additional manufacturing by other contractors to meet wartime demands. Deployment of the SCR-536 commenced in 1942, marking its integration into U.S. Army operations as a portable alternative to cumbersome wired field telephones, particularly suited for mobile maneuvers where laying wire lines was impractical. It was issued at a rate of six units per rifle company, allocated one to each of the three rifle platoons, two to the weapons platoon, and one to the company commander; this distribution was notably implemented in the 29th Infantry Division. The radio facilitated squad-level coordination by enabling voice communication over short ranges without fixed infrastructure. The SCR-536 first saw combat use during the Allied invasion of in November 1942, providing critical short-range communications for units in fluid engagements. It subsequently supported operations in the invasions of and mainland in 1943, where its portability aided rapid advances, and played a key role in the on June 6, 1944, including with units like the 29th Infantry Division during the push inland from .

Design and Specifications

Physical Characteristics

The SCR-536, also known as the BC-611 radio receiver-transmitter, measures approximately 3.1 inches (80 mm) wide, 3.5 inches (90 mm) deep, and 12.6 inches (320 mm) long, designed in the form of an oversized telephone handset to facilitate one-handed by soldiers in combat. This compact, elongated shape allowed for easy portability while maintaining accessibility to controls during movement. The unit weighs 5.5 pounds (2.5 kg) including batteries, or approximately 3.9 pounds (1.75 kg) without, making it light enough for extended carry by personnel despite the inclusion of vacuum tubes and power sources. Its case is constructed from waterproof cast aluminum, providing durability against moisture, impacts, and harsh environmental conditions encountered on the . A key feature for mobility is the 40-inch (102 cm) telescoping , which collapses into the body for compact transport and extends fully for , secured by a protective cap with a . Ergonomically, the integrates a and speaker into its form, with a pistol-grip featuring finger grooves for secure hold and a strap for additional carrying stability during frontline use.

Electrical and Operational Specifications

The SCR-536 operated within a range of 3.5 to 6.0 MHz, equivalent to the 80-meter band, and supported up to 50 -controlled channels for (AM) voice transmission. Each unit was preset to a single fixed via its and associated coils, necessitating careful coordination among operators to avoid in networked use. The radio's power output was approximately 20 milliwatts (0.02 W) of radiofrequency (RF) energy, enabling short-range communications. Transmission employed 4 , while reception utilized 5 tubes in a configuration, allowing simultaneous receive and transmit capabilities in a compact design. Power was supplied by two dry-cell batteries: the BA-37 providing 1.5 volts for filament heating and the BA-38 delivering 103.5 volts for plate voltage. These batteries supported approximately one day of intermittent operation, yielding 10-20 hours of receive time and 4-8 hours of transmit time under typical usage, with current drains of 250 mA () and 11 mA (B battery) during reception, increasing to 300 mA and 35 mA respectively during transmission. Operational range varied by and conditions, typically spanning 100 meters to 1 mile (1.6 ) over in average environments, but extending up to 3 miles (4.8 ) over water or flat open ground due to reduced . The waterproof casing enhanced reliability in adverse weather, though primary performance depended on extension and .

Variants

The SCR-536 radio set was produced in several variants designated A through F, representing iterative production modifications rather than major redesigns, with changes primarily aimed at enhancing efficiency, reliability, and accessory compatibility while preserving the core frequency range of 3.5 to 6 MHz and power output. These variants collectively accounted for approximately 130,000 units manufactured by 1945, mainly by the Galvin Manufacturing Company (later ). The SCR-536-A, introduced in early 1942, incorporated minor production tweaks for improved reliability, including a shift from to dynamic () microphones and earphones in later production runs for better durability, along with adjustable coils covering ranges such as 3500-3825 kHz; it was issued with one set of spare crystals. The SCR-536-B, -C, and -D variants, entering production in 1943, were functionally similar to the A model but differed mainly in contracts and featured preset antenna coils tuned to specific frequencies (e.g., 4035 kHz) to streamline setup; the -C and -D models were supplied with Box BX-49, containing 12 sets of interchangeable coils and crystals for multi-channel flexibility, addressing early field needs for varied operational frequencies. The SCR-536-E, produced starting in , introduced subtle refinements to the overall design, maintaining compatibility with prior accessories while optimizing internal layout for minor size reductions. The final SCR-536-F (also designated BC-611-F), widely deployed in late-war operations, added a revised bottom cover with integrated jacks for external microphones and headsets, enabling expanded connectivity options, and supported up to 50 crystal channels for broader tactical adaptability; these enhancements improved usability without altering the baseline range limitations of 100 feet to 1 mile.

Components and Functionality

Core Components

The SCR-536 radio set utilized the BC-611 as its core unit, a compact device housing five miniature vacuum tubes designed for low-power, battery-operated operation in a handheld . This integrated both receiver and transmitter functions within a single aluminum , enabling portable two-way voice communication on frequencies between 3.5 and 6.0 MHz. The vacuum tubes employed in the BC-611 were battery-type miniatures optimized for efficiency and compactness: a 1R5 serving as the converter (mixing received signals with a for the in receive mode and as the crystal-controlled oscillator in transmit mode), a 1T4 as the (IF) amplifier, a 1S5 functioning as the second detector, automatic volume control (AVC), and first () amplifier, one 3S4 as the for and modulator for , and a second 3S4 dedicated to the RF power amplification during . These , with their low filament voltages (typically 1.4-1.5 volts), were mounted vertically on the to minimize space and heat buildup, contributing to the unit's overall portability. Key circuits within the BC-611 included a architecture, which converted incoming (RF) signals to a fixed 455 kHz IF for amplification and detection, providing stable sensitivity despite the unit's small size. For transmission, a circuit ensured frequency stability by generating a precise carrier signal, offset by 455 kHz from the receiver crystal to align receive and transmit channels, while a simple plate-modulated audio circuit using the 3S4 tube applied voice signals from the microphone to the RF carrier. These circuits were assembled using subminiature components, such as powdered iron core IF transformers and modular "cups" of tuned parts, to fit within the constrained internal volume. Internally, the and circuits were secured on an aluminum divided into compartments, with the and transmitter sections sharing components for efficiency; access was provided via a hinged bottom cover for maintenance. The unit features a built-in in the case body behind a protective grille, providing direct voice input to the modulator circuit. Channel selection was achieved by replacing plug-in rather than a continuous dial, with each crystal pair (one for receive, one for transmit) preset to a specific pair. Accessories supporting the core components included spare crystals for field reconfiguration to different channels, typically carried in a small kit to enable operation on up to 12 preset frequencies. A leather carrying case with an adjustable strap protected the during transport, while an optional headset with a dynamic earphone and allowed for hands-free or private listening, connected via a red plug to the unit's audio output.

Operation and Controls

The SCR-536 radio set was operated using a simple press-to-talk mechanism integrated into the handle, where depressing the switch activated the transmitter and muted the , while releasing it switched back to receive mode for listening through the built-in earphone. To initiate , soldiers inserted the required batteries—typically one BA-37 (1.5 V) for the filaments and one BA-38 (103.5 V) for the plate supply—into the bottom compartment, ensuring the positive ends faced outward, then secured the cover. The , a 39-inch telescoping , was fully extended to power on the set and optimize , which varied from about to one mile depending on ; retracting it turned the unit off. Users then held the set to their ear, selected the preset determined by the installed and coils (one of 50 possible frequencies in the 3.5–6.0 MHz , configured prior to field use), and spoke clearly into the grille while pressing the talk switch. The device featured no manual volume or controls, relying on fixed audio levels, which meant operators had to tolerate background noise when no signal was present. Basic procedures emphasized clear enunciation and synchronization of the press-to-talk switch to avoid cutting off transmissions, with the set's design allowing one-handed use during movement. Field maintenance was limited to user-accessible tasks, such as replacing depleted batteries (which provided roughly 15 hours of intermittent use) or swapping crystals and coils to change channels, performed by communications personnel using basic tools. Operators were instructed to check connections by tapping the case and to wipe away any from the moisture-sealed to prevent internal damage, but no further disassembly was recommended without specialized equipment. Training for infantrymen was straightforward, requiring no prior radio experience, and focused on battery insertion, antenna handling, press-to-talk technique, and the importance of brief transmissions to extend battery life amid the set's limited power supply. This simplicity enabled rapid familiarization, with emphasis on conserving energy by avoiding prolonged talks and ensuring the antenna remained extended only when needed.

Military Use

World War II Applications

The SCR-536 played a pivotal role in the of 1942, particularly during , where it was employed in improvised communication setups during initial landings to support small-unit patrols in desert conditions. Its short-range capabilities proved effective for coordinating infantry movements across open terrain, allowing leaders to maintain contact with forward elements without extensive wire networks. Early field testing in these arid environments validated its portability for mobile operations, marking one of the first combat deployments of handheld radios by U.S. forces. In the Sicilian campaign of 1943 during , the SCR-536 was used in company command nets for communication between platoon leaders, company commanders, and executives, aiding tactical coordination within infantry units. Its portability supported short-range voice communication during landings and early phases, supplementing messengers and wire, and was credited in after-action reports with saving "many hundreds of lives" through enhanced situational awareness. Captured units impressed German forces after encounters in , who noted its lightweight design and efficiency, influencing interest in portable radio concepts. During the Normandy invasion on D-Day in 1944, the SCR-536 enabled real-time coordination for U.S. forces during beach assaults and airborne operations. Airborne units, including the 82nd and 101st Airborne Divisions, used it for assembly and linking scattered paratroopers with ground elements despite equipment losses from drops. Its short range was effective in fluid conditions but limited by terrain. In the Pacific theater, the SCR-536 was issued to and infantry, paratroopers, and tank crews during island-hopping campaigns, supporting squad-level coordination in and amphibious assaults despite environmental challenges. The SCR-536 revolutionized across these campaigns by introducing wireless squad communication, which diminished dependence on vulnerable runners and messengers, thereby accelerating command decisions. After-action reports highlighted its life-saving potential through faster coordination of support. This shift allowed small units to operate with greater flexibility, providing clear voice links from leaders to higher commands and transforming the pace of ground maneuvers.

Limitations and Adaptations

The SCR-536 exhibited several key operational limitations that impacted its effectiveness in diverse environments. Its battery life was restricted to approximately one day of normal use, rendering it highly power-intensive and necessitating frequent changes during extended operations. The radio's range was typically limited to about 1.6 under ideal conditions, but performance degraded significantly in challenging terrain, often dropping to less than 500 m in hilly or forested areas due to signal . Additionally, despite being tropicalized and designed with features, the SCR-536 remained susceptible to moisture ingress, leading to and reduced reliability in humid or settings, where units could fail within a month of exposure. Reliability challenges further compounded these issues, particularly with the vacuum tube components prone to failure in extreme heat or , which prompted improvements in later variants for better environmental . Overuse during prolonged s could cause overheating, so operators adhered to recommended duty cycles—typically limiting continuous to short bursts—to prevent and maintain functionality. To address these drawbacks, soldiers implemented practical adaptations in the field. For extended range, relay stations were employed to bridge gaps in coverage, allowing messages to be passed sequentially over greater distances. security was enhanced through swappable crystals and coils, enabling changes to one of 50 channels within the 3.5–6.0 MHz band, though this required disassembly and tools like a . Training programs mitigated battery drain and interference by stressing brevity codes and concise messaging protocols, which minimized airtime and preserved power while reducing the risk of enemy interception.

Legacy

Technological Influence

The SCR-536 pioneered the concept of a compact, handheld by integrating all essential components—transmitter, , , earphone, , and —into a single, self-contained unit weighing approximately 5 pounds, which enabled one-handed operation and marked a significant advancement in portable radio . This design directly influenced post-World War II civilian applications, as Galvin Manufacturing Corporation (later ) adapted the for commercial walkie-talkies in the 1950s, such as early handheld models that brought communication to industries like and public safety. The emphasis on portability and battery efficiency in the SCR-536 also contributed to the foundational principles of modern cellular phones, demonstrating the feasibility of personal, mobile voice communication devices that evolved into today's smartphones. In military contexts, the SCR-536's legacy extended through direct successors like the AN/PRC-6, developed by Raytheon in the late 1940s as a replacement, which retained the handheld form factor while shifting to FM modulation and was deployed into the early 1960s, including during the Vietnam War for squad-level communications. Its core principles, including crystal-controlled frequency stability for reliable operation and amplitude modulation for voice transmission, were adapted in FM-based systems like the SCR-300 backpack radio, which expanded range and reliability while building on the SCR-536's low-power, portable ethos to support tactical coordination in later conflicts. The SCR-536 demonstrated the viability of battery-powered, low-power RF systems for personal communications, operating at 20 milliwatts with ranges from to a mile, which highlighted the potential for widespread adoption beyond use. This breakthrough was recognized in the community through extensive coverage in QST magazine, where it featured on the November 1942 cover and in advertisements, inspiring hams with its compact design and sparking interest in postwar handheld transceivers for civilian and applications. Galvin Manufacturing's designs for the SCR-536, developed and contracted in 1941, laid the groundwork for the company's advancements in FM radio technology, as chief scientist Daniel E. Noble integrated frequency modulation expertise to produce the SCR-300 shortly thereafter, influencing broader portable FM systems.

Collectibility and Preservation

The SCR-536, known as the Handie-Talkie, is highly sought after by vintage radio collectors for its pioneering role as one of the first portable handheld transceivers. Its rarity stems from wartime production and subsequent wear, making functional examples particularly valuable; auction estimates for complete units typically range from $400 to $600 USD. Restoration of SCR-536 units is a popular activity among enthusiasts. Common challenges addressed in such efforts include corrosion from leaked electrolytes damaging internal contacts and the need to replace aged vacuum tubes, often with modern equivalents like those substituting for the original 1R5 and 1T4 types. Preservation initiatives extend to institutional collections, with examples like the BC-611-C variant held by the in as part of its equipment archive (catalogue number COM 629). Online enthusiast communities, such as RadioNerds, facilitate preservation by sharing technical manuals, schematics from TM 11-235 and TM 11-310, and guidance on sourcing components like FT-243 crystals and replacement tubes. Key obstacles in maintaining operational SCR-536 radios include sourcing authentic BA-38 high-voltage batteries, which powered the plate supply and are no longer manufactured, often leading restorers to use modern alternatives. Legal operation is restricted to licensed operators under FCC Part 97 rules, requiring modifications to align the device's 3.5–6 MHz range with authorized amateur bands like 80 meters while ensuring compliance with emission and power standards.

References

  1. [1]
    The SCR-536 Handie-Talkie Was the Modern Walkie-Talkie's ...
    Sep 25, 2020 · Built by Galvin Manufacturing (which later became Motorola), the SCR-536 weighed just 2.3 kilograms and was “designed for operation under battle ...
  2. [2]
    Motorola Handie-Talkie SCR536 Portable Radio
    The most famous radio of the World War II era, the Handie-Talkie SCR536 handheld two-way radio, almost never came to be.
  3. [3]
    BC-611 - Crypto Museum
    Jun 7, 2022 · BC-611, also known as SCR-536, 1 handy talkie or walkie talkie, was a valve-based hand-held two-way radio transceiver, developed in 1940 by Don ...
  4. [4]
    Who actually developed the first Walkie-Talkie?
    The company went into full production of the SCR-536 in July of 1941, six months before Pearl Harbor. The Galvin team credited with the SCR-536 development is ...
  5. [5]
    The Talkies -- Handie and Walkie - Michael Wright
    Galvin sent Don Mitchell, his chief engineer, and Ray Yoder to Camp McCoy. During the inspection, Mitchell saw the heavy and cumbersome back-pack radios the ...Missing: Manufacturing | Show results with:Manufacturing
  6. [6]
    Wrist-Wearable Electronics - Engineering and Technology History Wiki
    Jul 22, 2014 · At about the same time, in 1940, Donald Mitchell at Galvin Manufacturing Corporation began developing a handheld AM transceiver that the U.S. ...<|control11|><|separator|>
  7. [7]
    Walkie-Talkies and “Operation Gold Rush” | Article - Army.mil
    Apr 22, 2022 · Radio Set SCR-536 was a first in the military communications field. The designers incorporated the microphone, earphone, batteries, antenna, and ...
  8. [8]
    [PDF] A Short History of the Handheld Transceiver - eHive
    The SCR-536 was de- veloped in 1940 by a team led by Don. Mitchell, Galvin's chief engineer. By July. 1941 it was in mass production, and at war's end ...
  9. [9]
    Wireless Equipment, Transceiver BC-611-C (SCR-536), "Handie ...
    It was used virtually everywhere in the world, weighed only 2kg, and was proofed against fungi and moisture. The SCR-536 was also modified for use in military ...Missing: prototypes testing 1940-1941
  10. [10]
    [PDF] The Technical Services THE SIGNAL CORPS: THE TEST - GovInfo
    ... SIGNAL CORPS: THE TEST. (December 1941 toJuly 1943) by. George Raynor ... SCR-536, the handie-talkie used by air- borne and parachute troops, called ...
  11. [11]
    U.S. Army Rifle Company (1944-45) - Battle Order
    Jun 6, 2021 · Six M1918A2 BAR automatic rifles and six M1A1 Thompson submachine guns were added to this weapons pool on 30 June 1944. *Six SCR-536 "handie- ...
  12. [12]
    [PDF] US ARMY COMMUNICATIONS IN EUROPE, 1942-45
    Until the new infantry radios SCR-300 and SCR-536 could be ready for ... of North Africa, Sicily, and Italy. Finally, US Army military communications ...
  13. [13]
    SCR-536 Radio Set BC-611 (Variants A, B, C, D, E and F)
    The first ever made AM "Handy-Talky", for the US-Service. One channel xtal-operation in the range 3.5 - 5.995 MHz. Variants -A to -F. Another part of SCR-536 is ...
  14. [14]
    [PDF] TM 11-235 RADIO SETS SCR-536-A, SCR-536-B,I . A SCR-536-C
    Over-all dimensions and weights of l"omponents are given in paragraph 2 ... the antenna of the radio set or varying the length of the wire will control the.Missing: ergonomics | Show results with:ergonomics
  15. [15]
    [PDF] TM 11-4019 - Crypto Museum
    FILAMENT AND BIAS VOLTAGES MEASURED ON 30 VOLT RANGE. OF VOLT-OHMMETER UNIT OF SIGNAl CORPS TEST SET 1-56-("). All OTHER VOLTAGES MEASURED ON 300 VOLT RANGE. "A ...
  16. [16]
    [PDF] RADIO SETS SCR-S36-A, -B, -C, -D, -E, AND -F"
    This manual supvrsedes TM 11-235, 14 May 1943, including C 1. 15 December ... Set SCR-536-(*) .............. . Frequency Spectrum Chart . . 0 0 ...
  17. [17]
    Inside the Handie-Talkie, July 1946 Radio-Craft - RF Cafe
    Oct 29, 2021 · The SCR-536 is designed for two-way voice communication over distances up to one mile. The effective range is often decreased by terrain ...
  18. [18]
    [PDF] TM 11-235 - Crypto Museum
    Radio Set SCR-536--A, -B, -C, -D, -E, or -F consists of a five-tube, low-power, dry-battery-oper- ated radio receiver and transmitter, and certain ac- cessories ...Missing: variants improvements clarity stability
  19. [19]
    [PDF] THE BC-611, - SCR-536 HANDY-TALKIE
    Handie-Talkie signals the attack! HANDIE-TALKIE IS. ANOTHER MOTOROLA RADIO FIRST! The FIGHTINGEST Radio in the Armed Service.Missing: weight ergonomics
  20. [20]
    [PDF] JUN 9-/1945 - RadioNerds
    A short training period was given to the new personnel before being assigned ... Radio Set SCR-536-( ) plus spare batteries (4 sets). Radio Set SCR-593 ...
  21. [21]
    Motorola Handie-Talkie SCR536 Portable Radio
    Motorola's Handie-Talkie Portable Radio changed the way the WWII was fought. Find out more about the history of the Handie-Talkie radio.Missing: prototypes testing waterproofing ease
  22. [22]
  23. [23]
    [PDF] Reports of Signal Corps Units Engaged in the Sicilian Campaign ...
    Aug 25, 2023 · Signal Corps Equipment. &» SCR-511 is aB excellent set but should b ... SCR-536 of infantry AT Go are of no value, SCR-510 ox 610.
  24. [24]
    [PDF] The Evolution of Communications in the Military as it Relates to ...
    Aug 30, 2017 · The walkie-talkie (SCR536) was the primary means of radio communications during WWII for small tactical units such as platoons and companies.
  25. [25]
  26. [26]
    The Noisy Line Page
    The US Signal Corps designated the Handie-Talkie as the SCR-536 (i.e. Set, Complete, Radio 536). This number referred to the complete installation i.e. the ...
  27. [27]
    Walkie Talkie History: From World War II to Nextel - Tedium
    Aug 17, 2017 · Walkie-talkies even inspired a major cell phone network ... A signaler with the SCR-536 walkie talkie, the first hand-held model.
  28. [28]
    The 50-year story of cell phones that changed communication
    May 19, 2025 · During the Second World War, the SCR-536 Handie-Talkie played a crucial role in advancing the technology of portable two-way radio transceivers.
  29. [29]
    [PDF] History of the Squad Radio - DTIC
    a. Battery life 72 hours desired b. 1:24 Trans - Rec ratio. 10. Priority of Characteristics a. Range b. Two preset channels c. Size and weight d. Cost e.
  30. [30]
    [PDF] The First Walkie-Talkie Radio - Repeater Builder®
    Enter the SCR-536, the famous handie-talkie, shown at right in a staged photo of a beach landing (note adoption of the then-new helmet as compared to the ...
  31. [31]
  32. [32]
    BC-611 - RadioNerds
    May 12, 2025 · Frequency Range: 3.5 - 6.0 mHz ; Modulation Type: AM ; Number of Crystals: One transmitter and one receiving crystal required per channel ; Preset ...