L79, TV’s Signal Strength Meter


This circuit was designed to assist the installation of TV antennas. The signal is monitored using a small portable TV set and this circuit monitors the output of the TV's FM detector IC via a shielded lead. To initially calibrate the meter, adjust trimpot VR2 to zero the meter. Trimpot VR1 is a sensitivity control and can be set for a preset reading (i.e. 0dB) or can be calibrated in millivolts. Rotating the antenna for a minimum reading on the meter (indicating FM quieting) gives the optimum orientation for the antenna.


Components-

  • Q1, Q2 = BC337

  • VU meter EX tape

  • RCA Socket

  • Resistors = 470K, 5.6K, 15K, 330R (ohm)

  • VR1 = 5K, VR2 = 2.2K

  • Capacitors = 33pf, 2.2uf (2),

  • Battery 9volt

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