A while ago I procured a used MFJ Model 784B tunable DSP filter. I found that the audio output was not working but the output was active thru the headphone, which I piped into an amp and a speaker ok. It works ok this way, but I am not enamored with it. I made the cables for the power and audio to the radio. I also made a binder with the instruction manual. If anyone out there has an interest in it, it can be yours. Or if someone has experience with it and could offer some insight into its workings, I would be obliged.