Radio Shack 20-412 Scanning Receiver

RadioShack Corporation 20-412, RadioShack Pro-2036, Police Scanner / Communication Receiver FCC ID AAO20-412 AAO-20-412, AAO 20412, AAO20-412, AAO2O-412, AAO20-4I2, AA020-412

A 200-channel desktop scanner designed for enthusiasts interested in monitoring a variety of radio transmissions. Released in the mid-1990s, this model was part of Radio Shack's extensive line of scanning receivers and offered a blend of user-friendly features and broad frequency coverage suitable for hobbyists at the time.

Key Features and Specifications:

• Channels: The 20-412 has 200 programmable channels, organized into 10 banks of 20 channels each. This allowed users to group frequencies by category (e.g., police, fire, ham radio) for easier access and scanning.
• Frequency Coverage: It covers a wide range of bands, including:

29–54 MHz (VHF Low, including 10-meter ham band and 6-meter ham)
108–136.9875 MHz (Aircraft)
137–174 MHz (VHF High, including 2-meter ham band and military land mobile)
380–512 MHz (UHF, including 70-cm ham band and federal government frequencies)
806–956 MHz (UHF public service bands, excluding cellular frequencies)

• Modes: It supports AM and FM modulation, making it versatile for listening to aviation (AM) and public safety or ham radio (FM) transmissions.
• One-Touch Search Banks: The scanner includes preprogrammed search banks for specific services like ham radio, police/fire/emergency, aircraft, weather, and marine frequencies. This feature simplified finding active channels without manual frequency entry.
• Scan Delay: A two-second delay before moving to the next channel ensured users could hear replies on the same frequency, enhancing the listening experience.
• Memory Backup: It retains programmed frequencies during power loss, though the duration depends on the condition of an internal capacitor or battery (not always specified in user reports).
• Power Options: The unit operates on AC power via an included adapter (12V, 300 mA) or can be powered from a vehicle’s 12V source with an optional DC cord and Adaptaplug.

Physical Design:

• Display: It features a basic LCD for showing channel numbers, frequencies, and status indicators.
• Antenna: Comes with a telescopic antenna for local reception, with a BNC connector for attaching external antennas to improve range and signal quality.
• Controls: Includes a keypad for manual frequency entry, bank selection, and scanning controls, along with volume and squelch knobs.

Performance and Use:

The 20-412 was designed to monitor conventional analog transmissions, such as those from police, fire departments, ambulance services, government agencies, aircraft, and amateur radio operators. It lacks trunking or digital decoding capabilities, reflecting its era before widespread adoption of trunked systems (e.g., Motorola Type I/II) or digital formats like P25. Users could manually program frequencies or use the search function to discover active ones, storing them into the 200-channel memory. Its sensitivity and selectivity were typical for mid-90s desktop scanners, performing well with strong local signals but potentially struggling with weaker or distant transmissions without an external antenna. The one-touch banks were a standout feature, offering quick access to popular frequency ranges, though users needed external resources (like frequency guides) to program specific local channels.

Legal Considerations:

The scanner complies with FCC Part 15 rules for scanning receivers, meaning it’s legal to listen to most receivable transmissions. However, it cannot legally intercept cellular phone frequencies (blocked in hardware), encrypted communications, or other restricted signals under the Electronic Communications Privacy Act (ECPA).

Availability and Legacy:

The 20-412 is no longer in production, but it remains available on secondary markets like eBay, often sold used with varying conditions (e.g., with or without power supply or antenna). Prices typically range from $50 to $100, depending on functionality and accessories included. It’s a nostalgic piece for scanner enthusiasts, valued for its simplicity and reliability in an age before digital radio dominance. For detailed programming instructions or troubleshooting, the original owner’s manual (not widely available online for this specific model) or Radio Shack scanner forums like those on RadioReference.com are recommended resources. This model reflects a time when analog scanning was at its peak, offering a straightforward tool for exploring the airwaves.