UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - 6-gang FM stereo tuner heads

regenfreak · 23rd Jul 2022, 10:11 pm

OK, in your circuit, it has a series LC and parallel LC plus two 50 ohms. At the resonant frequency, the series LC has very low impedance, only a narrow band can pass through. The parallel LC has very high impedance so the two 50 ohms resistors have no effect on the circuit.

Outside the bandpass freqencies, the opposite happens. The parallel LC appears as a low impedance path and they see the two 50 ohms resistors to the ground.

23rd Jul 2022, 10:11 pm	#132
regenfreak Heptode Join Date: Nov 2018 Location: London SW16, UK. Posts: 655	Re: 6-gang FM stereo tuner heads OK, in your circuit, it has a series LC and parallel LC plus two 50 ohms. At the resonant frequency, the series LC has very low impedance, only a narrow band can pass through. The parallel LC has very high impedance so the two 50 ohms resistors have no effect on the circuit. Outside the bandpass freqencies, the opposite happens. The parallel LC appears as a low impedance path and they see the two 50 ohms resistors to the ground.