The Redifon SPT9010 is a solid-state, high-frequency (HF) or very-high-frequency (VHF) communications system, specifically designed as a 24-channel transmitter and receiver combination. It was part of Redifon’s prestigious “SECO” (SEquential COmmunication) product line, which was renowned for its reliability and advanced features for its time. This system was intended for demanding fixed-station, marine, or mobile applications where robust and clear multi-channel communication was essential.
The unit is housed in a heavy-duty, rack-mountable case, characteristic of professional and military-grade electronics of the era. Its construction emphasizes durability, serviceability, and stable performance.
Key Features & Specifications
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Channel Capacity: 24 fully synthesized channels. This allowed operators to quickly switch between multiple pre-set frequencies without manual tuning.
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Frequency Range: Typically covered a VHF range, such as 68-88 MHz or 100-156 MHz (Marine VHF Band), though specific ranges depended on the customer order. Some variants were built for the HF bands.
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Technology: Fully solid-state (transistorized), a significant advancement over older valve/tube-based equipment. This resulted in lower power consumption, less heat generation, and greater reliability.
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SECO System Compatibility: As a “SECO” product, the SPT9010 was designed to work within a network where multiple stations could share a limited number of channels efficiently, often using techniques like Selective Calling (SELCAL). This meant a station would only alert the operator when it was being specifically called, reducing noise and operator fatigue.
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Modulation: FM (Frequency Modulation) for clear, static-resistant voice communication.
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Power Output: Typically in the range of 10 to 30 watts, providing a strong signal for its intended applications.
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Construction: Built to high environmental standards, likely to specifications such as DEF-133 (a UK military standard), making it resistant to moisture, vibration, and temperature variations.
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Interfaces: Featured a comprehensive rear panel with connectors for:
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Primary Power (e.g., 24V DC for mobile/marine, or 110/240V AC for fixed stations)
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RF Antenna Output
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Audio Input/Output (for microphones, speakers, and remote control heads)
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Remote Control Capability for use in bridge consoles on ships or control rooms.
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Typical Applications
The SPT9010 was used in scenarios requiring robust and reliable medium-to-long-range communications:
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Marine Communications: A primary application. Installed on ships for ship-to-ship and ship-to-shore communication, often in the international marine VHF band.
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Military & Defence: Used by armed forces for ground-based and vehicle-mounted command and control networks.
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Aeronautical Ground Services: For communication between control towers, ground crews, and aircraft on the ground.
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Emergency Services & Government: For reliable network communications for police, fire, or other civil authorities.
