I designed the AF amp to have 1KOhm input. Now to try the detector with 1K load. First a look with 1nf coupling.(my earlier posted circuit.)
It has been suggested just use a larger coupling cap. So let's try .1f.
WOW! That cut the output plum near in half! Maybe the larger coupling cap is not such a good idea. Let's try 500p.
so does the coupling cap matter?