Maybe this will help:
In the diagram below, R1 limits the current that can be drawn from the discriminator tap, C1 blocks the flow of DC current, and R2 is a shunt that prevents any DC bias on the output to the sound card. R1 should be in the 10KΩ-100KΩ range, and R2 should be about 10x the value of R1. The interaction between C1 and R1 and R2 determines the low frequency cutoff on the output side. The larger the value, the more low-frequency audio will pass. A 10μF capacitor should be fine.
In the diagram below, R1 limits the current that can be drawn from the discriminator tap, C1 blocks the flow of DC current, and R2 is a shunt that prevents any DC bias on the output to the sound card. R1 should be in the 10KΩ-100KΩ range, and R2 should be about 10x the value of R1. The interaction between C1 and R1 and R2 determines the low frequency cutoff on the output side. The larger the value, the more low-frequency audio will pass. A 10μF capacitor should be fine.
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