Move the external FM filter so it's before the amplifier. It does little to no good after the amp. The internal filter in your amp is ineffective at the low end of the FM band and it's the low end of the FM band (90-93 MHz) that has the greatest potential to cause 2nd harmonic interference into channel 8's bandwidth.
I have no idea if this will solve your particular issue, but its a glaring error in the connection scheme. I always recommend fixing the obvious first to get those issues off the table.
|