Introduction
The CW-38 is a high‑power continuous‑wave (CW) radio transceiver that was manufactured from the early 1970s until the mid‑1990s by the British company CW Engineering Ltd. Designed primarily for use by amateur radio operators, maritime communication stations, and emergency services, the CW-38 became a standard in the industry due to its reliability, robust construction, and versatility across a wide frequency range. The name “CW-38” derives from its designation as a Continuous‑Wave transceiver operating on the 38‑MHz band in the early prototype stage, although the final model covered a broad spectrum from 1.8 MHz to 54 MHz.
History and Development
Origins
In 1969, CW Engineering Ltd. identified a market need for a durable, high‑gain transceiver that could support both amateur and professional users in challenging environments. The company’s founder, John L. Carter, was an amateur radio enthusiast who had experienced the limitations of existing transmitters, especially their susceptibility to power surges and the difficulty of operating in remote locations.
The initial research and development phase began with the creation of a prototype referred to internally as the “Model 38.” The designation reflected the prototype’s main operational frequency of 38 MHz, a mid‑band frequency chosen for its balance between range and atmospheric propagation characteristics. The prototype was successfully tested in a series of field trials, demonstrating a power output of 100 W and a modulation accuracy that met the emerging standards for Morse code communication.
Commercial Release
After two years of iterative improvements, CW Engineering introduced the first commercial version of the CW-38 in 1973. The release coincided with the International Radio Regulation meeting, where the device received approval for operation on amateur and maritime frequencies. The transceiver was priced competitively and marketed through radio hobbyist magazines, trade journals, and direct sales to maritime authorities.
Evolution of the Model
Over its production life, the CW-38 underwent several revisions, each adding new features and refining performance. The most notable updates included the 1976 “CW-38A” variant, which incorporated a solid‑state oscillator for reduced frequency drift; the 1982 “CW-38B,” which added a dual‑band tuning mechanism; and the 1989 “CW-38C,” which introduced an integrated power‑management system for battery operation.
Discontinuation
By the mid‑1990s, advances in digital modulation and the rise of portable satellite communication devices rendered the CW-38 less competitive. CW Engineering ceased production in 1995, after more than 120,000 units had been sold worldwide. Despite its discontinuation, the CW-38 remains in use in many remote and emergency communication setups due to its proven durability.
Technical Specifications
Frequency Range
- 1.8 MHz – 54 MHz (VHF and HF bands)
- Multiple sub‑band tunings available: 1.8–6 MHz, 6–12 MHz, 12–18 MHz, 18–27 MHz, 27–40 MHz, 40–54 MHz
Power Output
- Continuous wave: 100 W (max)
- Pulse mode: 500 W peak (for certain emergency applications)
Modulation
- Primary: Morse code (CW) with adjustable bandwidth from 1.5 Hz to 15 Hz
- Secondary: Single sideband (SSB) and Amplitude Modulation (AM) for specific maritime traffic channels
Physical Dimensions
- Overall: 48 cm × 28 cm × 10 cm (length × width × height)
- Weight: 8.5 kg (excluding power supply)
Construction
- Enclosure: Marine‑grade aluminum alloy with corrosion‑resistant anodized finish
- Components: Solid‑state oscillator, high‑voltage power supply, printed circuit board (PCB) with 1.6 mm FR‑4 substrate
- Cooling: Passive heat sink with forced air intake for extended operation periods
Power Requirements
- AC mains: 220 V ± 10 %, 50 Hz (Europe), 110 V ± 10 %, 60 Hz (North America)
- Battery: 12 V DC, 50 Ah lead‑acid battery (for mobile operation)
Interfaces
- Input: 12 V DC power jack, optional 24 V DC for higher‑power operations
- Output: RF connector (TNC type) for transmission, and a balanced line for reception
- Control: 5‑pin DIN connector for external control, including frequency selector and power level
Operating Modes
Continuous‑Wave (CW) Mode
The CW mode is the primary operational mode of the CW‑38, designed for Morse code transmission. The device offers adjustable keying speeds ranging from 5 to 60 words per minute (WPM), with the ability to lock the carrier frequency for precise tuning. The CW output can be directed to an external antenna system via the RF connector, allowing for both mobile and fixed installations.
Single‑Sideband (SSB) Mode
In certain maritime and emergency applications, the CW‑38 can be switched to SSB mode. This allows for voice communication with limited bandwidth (0.75 kHz to 1.5 kHz), providing a cost‑effective alternative to conventional radio voice systems. The SSB mode also supports optional Automatic Frequency Control (AFC) for maintaining carrier stability.
Amplitude Modulation (AM) Mode
AM mode is available for broadcast of short audio signals, typically used by emergency services for issuing alerts. The AM output features a built‑in limiter to protect against signal distortion during high‑power transmissions.
Pulse Mode
For applications requiring rapid burst transmission, such as search‑and‑rescue beacon signals, the CW‑38 can operate in pulse mode, delivering peak powers up to 500 W for short intervals. The pulse width is adjustable from 10 µs to 10 ms, enabling flexible adaptation to different propagation conditions.
Applications
Amateur Radio
Amateur operators widely adopted the CW‑38 for its robust design and high output power. The device’s compatibility with a broad frequency range made it suitable for contests, field day events, and long‑distance “DX” communications. The CW‑38’s reliable modulation accuracy facilitated participation in international Morse code championships.
Maritime Communications
The maritime sector employed the CW‑38 to maintain line‑of‑sight communication between vessels and coastal stations. The transceiver’s ability to operate on specific maritime channels, coupled with its solid‑state power supply, ensured dependable operation even in harsh marine environments. Many coast guard units across Europe and North America integrated the CW‑38 into their emergency response suites.
Emergency Services
Disaster relief organizations utilized the CW‑38 for establishing communication links in areas where infrastructure had been damaged or destroyed. Its battery‑operated mode allowed for deployment in remote regions, and the high‑gain antenna compatibility extended operational range up to 200 km in favorable conditions. The device’s pulse mode was especially valuable for sending distress alerts to rescue teams.
Military Training
While not intended for direct combat use, the CW‑38 was employed by military training units for signal discipline and radio operation courses. The transceiver’s straightforward controls and clear indication of frequency and power levels made it an effective teaching tool for new recruits.
Educational Use
University radio clubs incorporated the CW‑38 into their curricula, using it for practical lessons on radio theory, modulation, and antenna design. The device’s durability also made it suitable for laboratory projects that required repeated testing under variable conditions.
Variants and Models
CW‑38A
Released in 1976, the CW‑38A incorporated a solid‑state crystal oscillator, reducing frequency drift and increasing stability under temperature variations. The A variant also introduced a simplified front‑panel layout, with dedicated push‑buttons for mode selection.
CW‑38B
In 1982, the CW‑38B model added a dual‑band tuning knob, allowing users to switch between HF and VHF bands without accessing the front panel. This improvement was particularly appreciated by operators who required rapid frequency changes during contests or emergency operations.
CW‑38C
The 1989 iteration, CW‑38C, introduced an integrated power‑management system that enabled the device to operate from a 12 V battery supply. The system automatically adjusted power output to extend battery life, making the C variant ideal for mobile operations.
CW‑38D
Although never released as a commercial product, a prototype CW‑38D was developed in 1993 with an upgraded high‑power output of 150 W and a digital frequency counter. The prototype was evaluated by a small group of field engineers but was shelved due to market shifts towards digital communication systems.
Impact on Communications
Standardization of Amateur Radio Equipment
The CW‑38 contributed to a period of standardization within the amateur radio community. Its widespread adoption fostered a common set of operating practices and facilitated the exchange of best practices among operators worldwide. The transceiver’s compatibility with a variety of antenna systems also encouraged the development of new antenna designs optimized for CW transmission.
Enhancement of Maritime Safety
By providing a reliable, high‑power communication link, the CW‑38 played a role in improving maritime safety during the 1970s and 1980s. The ability to transmit over long distances without reliance on satellite infrastructure reduced the risk of communication loss during storms or equipment failures.
Legacy in Emergency Response
The CW‑38’s battery‑operated capabilities and rugged construction have made it a staple in emergency response kits. Many retired operators continue to rely on the device in disaster relief scenarios, and its enduring presence underscores the importance of analog communication in situations where digital networks may fail.
Contemporary Usage
Legacy Systems
Despite its discontinuation, the CW‑38 remains operational in a number of legacy systems. Many radio clubs maintain active stations featuring the CW‑38, often in conjunction with modern digital modes, for the purpose of preserving historical equipment and providing a tactile learning experience.
Collector’s Item
Collectors of vintage radio equipment view the CW‑38 as a significant artifact of radio history. The transceiver’s robust design and historical importance contribute to its desirability among enthusiasts who specialize in classic analog communication devices.
Experimental Research
Research groups studying the propagation characteristics of continuous‑wave signals sometimes employ the CW‑38 in field experiments. The transceiver’s adjustable output power and frequency stability make it a suitable platform for controlled studies of HF and VHF propagation phenomena.
Related Equipment
WJ‑23 Transceiver
The WJ‑23 was a contemporaneous amateur radio transceiver that targeted a different frequency range (160 kHz to 30 MHz). While the WJ‑23 offered broader coverage, it lacked the CW‑38’s high‑power CW capabilities, making the two devices complementary in many users’ arsenals.
Maritime Radio Model M‑4
Model M‑4, produced by the Maritime Communication Corp., served as an alternative to the CW‑38 for marine operations. It featured a more compact design but did not provide the same level of power output, which limited its use in long‑range communications.
Modern Analog Transceivers
In recent years, analog transceivers such as the A‑Wave 900 and the R‑Tech 1500 have reintroduced high‑power CW operation. These modern devices incorporate digital control systems while maintaining the core analog transmission principles that made the CW‑38 popular.
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