IT-12

The Heathkit IT-12 is a visual-aural signal tracer from 1962, designed for troubleshooting audio and RF circuits in radios and TVs. It uses vacuum tubes and a probe to detect signals, with a speaker and «magic eye» tube for output indication.

• Manufacturer: Heathkit, Heath Co., Benton Harbor, MI, USA
• Type: Signal tracer (test equipment)
• Year: 1962
• Dimensions: ~305 x 165 x 140 mm (estimated from images)
• Weight: ~3–4 kg
• Power: 117V AC, 50–60 Hz, 25W, transformer-operated
• Connections:
  • Input: Single probe (switchable audio/RF)
  • Outputs: Two banana terminals (speaker), three binding posts (B+, P, CT for transformer)
• Technical Specs:
  • Tubes: 12AX7 (dual triode, input amplifier), 12CA5 (output), 1629 (magic eye)
  • Speaker: 3.5″ internal
  • Amplifier: High-gain, 2-stage vacuum tube
  • Frequency: Audio and RF (diode detector for RF)
• Highlights:
  • Dual-Mode Probe: Switchable for audio or RF, with diode detector for RF demodulation, simplifying circuit tracing.
  • Visual & Aural Output: Green «magic eye» tube shows signal strength; internal speaker plays audio or detected signals.
  • Versatile Testing: Traces signals from antenna to audio stages, ideal for pinpointing faults in radios/TVs.
  • Substitute Speaker/Transformer: Three binding posts (B+, P, CT) allow testing audio amplifiers when powered off, using internal speaker/transformer.
  • Noise Locator: Detects noisy or intermittent components in circuits.
  • User-Friendly: Simple controls (gain, speaker switch) for rapid troubleshooting without complex tuning.
  • DIY Kit Appeal: Sold as a kit for hobbyists, balancing cost and functionality.