Q meter Experiment

  Procedure:

  1. Set the Shunt Resistance (Rsh) value as small as possible (Say=0.02 Ohm). Set all the parameters of unknown coil. A sample parameters may be this (Say, L=5.277*E-5, R=100, Cd=20pF ).

  2. Set the voltage value of the oscillator (V=10 V).

  3. At f=1Mhz. Check the value of voltage drop across capacitor. (VC).

  4. If Vc at maximum during resonance, click simulate to measured the value of Q meter. Else change the frequency.

  5. Find Q true value by changing the tab to "Q true".

  6. Find Discharge capacitance (Cd) from "Discharge capacitance" tab: 1st resonance occurs due to frequency (say f1). Note down the value of tuning capacitor C. (say C1). Set the next resonance occurs at (say 2*f1). Note down the value of tuning capacitor C. (say C2). Discharge capacitance (Cd) would be =(C1-4*C2)/3.
  •   1. Switch on the above circuit.
      2. Search for maximum 'Vc' at a particular 'f' by varying 'C'.
      3. Then click on simulate to get the value of Q-measured.
      Vc (in volt):   Vsh (in volt):   Q-Measured:
  •   Click on the Simulate button to get the Q-True value.

      Q-True:

  •   Click on the Simulate button to get the Discharge Capacitance value.
      Maximum Voltage at 'C', Vc (in volt):
      Oschilator output, Vsh (in volt):
      Discharge Capacitance Cd:

Tutorials Point