Question

Example 2: Calculate the BW for the modeled tuning circuit of the Fig. below at the Frequencies: 540 kHz (bottom of AM dial); 980 kHz (middle of dial); 1620 kHz (top dial) Comment your results. L1 500 μΗ LOOPSTICK C1 R (load) 100 K R (load) is the combined coil loss (L1) and input resistance of U1. It represents all the losses in the tuned circuit. 150 pF TUNING Parallel resistance X Q for loaded parallel resonant circuits: capacitive or inductive reactance Bandwidth BW = Q Note: An ideal receiver should have Constant BW and therefore Constant selectivity (Q). The TRF approach fails! This example proves that!

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Answer 1

At S40 KHy Xp 2L 2TX 540 Ka 500 N ,696,46 2 Re S8, 9 - 540K Bw I, 1584 KHy - S8.96 980 KHy At 3, 018,76 A. 32,50 - 3.072 K dx 980K B W2 30, 153 KH 32,S0 6 20 KHz At Xp 2TTX 1620 KX SO0M 5.089 kY 00 K S9 G 5.089 K 1620 K BWa 8 2,44 KI 19,65 5 en tuning at diforent fri a boue Ckt FYom Yesults, difterent Band udis has