Ok, did some experimenting when I got home from work. I did this on a Cobra 2000 GTL. I got the best results by using a non-polarized .22uf mica dipped capacitor with a 22 uH choke in series. This netted me about 150% positive peaks, about 90% negative peaks with no changes in audio tone or clarity. SSB output and audio were also unaffected.
This time, I DID get audio checks from a neighbor of mine that's about 4 miles down the road from me, and he gave me the reports posted above. Is this the ultimate answer to compressing the negative peaks for AM CB? Probably not. But it sure is fun to experiment.
Just for giggles, I did it the original way, with the 10uf 25V electrolytic cap, and gave my neighbor a holler, he told me I sounded flat and muddy. Removed the cap, and it cleared me up immediately. Positive peaks on the Cobra 2000 with the electrolytic cap were close to 200%.
Also of note, I tried several different values of electrolytic caps, from .047uf to 10uf. They all did the exact same thing, both on the scope and in actual audio checks, all sounded muddy and flat. It seems as though it works better with a non-polarized capacitor, I had better adjustability of the AMC circuit, as well as better performance from an audio standpoint. And while my positive peaks weren't as high with the non-polarized cap (150-160%), that's really no big deal. Who wants to have 200% positive peaks anyhow, when you're sacrificing audio quality? I wouldn't.
If anyone is interested in some scope pictures, I'll gladly take some and post if requested.
~Cheers~
