Heathkit Virtual Museum

AJ-21 AM Tuner

AJ-21 AM Tuner


  • "Fidelity" Selector Switch
  • Three tuned stages
  • Self-powered
  • Exciting new styling

With the exciting new styling of charcoal grey enamel on its steel cabinet and ivory-colored bezel and lower front panel, the Heathkit AJ-21 AM Tuner proudly awaits display in any room in your home. This superb successor to the AJ-20 brings you high fidelity AM reception at a budget price and in a size convenient to everyone...for bookshelves, tables, etc.

This self-powered unit has three tuned stages for high sensitivity and a full wave voltage doubler detector for lower distortion. The "fidelity" switch gives you a choice of maximum selectivity or maximum fidelity. One of the two outputs is the variable level cathode follower type for the direct driving of power amps, regardless of cable length...the other output is fixed for use with preamplifiers. Has built-in rod antenna and provision for external antennas. Flywheel tuning and edge-lighted slide-rule dial.

AJ-21 Internal View

This inside view of the AJ-21 shows the clean, straight-forward circuitry employed by Heath engineers to provide dependable performance and ease of assembly.

SPECIFICATIONS—Tuning range: 550 kc to 1600 kc. Intermediate frequency: 455 kc. Sensitivity (for 20 db quieting IHFM standards): 1000 kc—8 uv. IF bandwidth (6 db down): NORMAL—2 kc.; MAXIMUM—18 kc. Output impedance (cathode follower): 5000 ohms. Input signal for 1 volt output: 2.5 uv—30% mod, 1000 kc. Image ratio: 1000 kc—50 db. Harmonic distortion (750 uv 95% mod.): Less than 1%. Hum and noise (500 uv—30% mod.): 40 db. IF rejection: 1000 kc—35 db. Tube complement: 2-6BA6, RF amplifier-IF amplifier, 1-6BE6, Oscillator-mixer, 1-12AU7, AF amplifier-Cathode follower, 2-Crystal Diodes, Audio Detector, 1-Silicon Diode, Rectifier (Power Supply), 1-No. 47 Pilot Lamp (Dial Illumination). Power supply: Transformer operated (fused). Power requirements: 117 V AC, 50/60 cycles at 19 watts. Dimensions: Overall—including cabinet and feet, 4-15/16" high x 13½" wide x 6" deep. Shipping Weight: 9 lbs.

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