Some progress. I checked if the audio trap is on 5.5 MHz used in Italy, and the interference in the sound is disappeared. Remains the problem of low power audio, I tried to connect my walkman to the volume control and I saw that the audio is low and distorted, the problem is in the power audio output. Tomorrow I check some capacitors, including the coupler capacitor between 6T8 and 6W6 and the capacitor between the anode and cathode of the 6W6
