AT-21 ​Aircraft ADF System Trainer

Model AT-21 Aircraft Automatic Direction Finder Equipment Trainer is designed to provide hands-on training on a real and operational equipment approved for aircraft installation. The equipment is mounted on a mobile workstation containing aircraft ADF unit, ADF indicator, and ADF loop and sense antenna assembly package. Aircraft quality electrical shielded wiring, cables, connectors, and harness assemblies and easily removable ADF antenna with coaxial cable connections. All interconnections are of aircraft quality electrical shielded wiring, cables, connectors, and harnesses. The workstation includes a test panel console for bench testing of ADF equipment.

Using Model AT-21, Avionics Instructors can effectively teach students on installing, removing, and testing an ADF unit.Students also develop proper understanding and learn how to troubleshoot the ADF equipment.


  • Durable, steel frame, Vertical standing panel with sturdy casters
  • Wood shelf
  • Accessories storage case
  • Adjustable height equipment panels
  • Adjustable height test panel
  • ADF Indicator
  • Avionics panel, complete with Allied Signal KX 155 with Indicator
  • Power Supply with voltage and current meters, power cord
  • Installation and mounting kit
  • Aircraft Antenna mounted on rotating mechanism

Test Panel Specifications:

Metering is provided by a panel mounted digital meter. The meter switch selects the following inputs:

The Automatic Direction Finder Test Panel is engineered for the bench testing of ADF receivers. The panel has a digital meter to monitor input voltage and current, as well as, several output voltage test points. The panel has a built-in speaker for audio monitoring.

The following lists the Model AT-21 panel functions and controls:
  • Combined Voltmeter/Ammeter (Digital readout)
  • 4-digit thumbwheel frequency selector
  • Speaker
  • 3-Position Band Switch (low, Medium, High)
  • Audio Gain Control Knob
  • RF Gain Control Knob
  • Fuse for DC Power
  • Power On Indicator
  • AC Selector (INT. or EXT.) Six panel-mounted jacks
  • Five Function Control Switches
  • ADF Connector
  • RMI Connector
The panel has 56 Breakout Jacks for access to a variety of signals and functions.

Communication section provides the following common test points and switches.
  • Metering of the supply voltage and current draw
  • Microphone input
  • Key Switch & Lamp Panel speaker (monitors speaker or phone/interphone channels)
  • Squelch control and Disable
  • Tuning Lamp Indicator
  • Serial or Parallel controller selection
  • Headphone Output Jack (monitors phone/interphone & aux audio channels)
  • Test Point Jacks for - Audio (microphone audio Comm input), Audio (microphone intercom audio input), Audio (Comm audio out), Audio (sidetone / aux audio out), Audio (speaker audio).


  • Technical Reference Manuals
  • Students’ Manual
  • Wiring diagram

Computer Based Training:

Model AT-21 is supplied with CBT covering the relevant topics, at no additional cost.

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