Hi,

I've been trying to build my first superhet but I have been having problems.

What I have been doing is building seperate boards for each of the
stages and debugging them seperately. I worked on the audio stages
first.

My two AF boards a 1) a low level X100 amplifier, and 2) an LM386
based power amplifier connected to speaker by RC network. Power
supply is a 9V battery.

Each of these boards work fine seperately, I have tested them with an
audio signal source and a scope. I used ground plane construction with
each of these.

However, when I try to use capacitive or inductive coupling between
the stages, I get the classic symptoms of motorboating... 10 to 45 hz
out of the loudspeaker.

I have the ground planes of each respective board on a piece of aluminum
foil, and both boards are connected in parallel to the 9V battery.

Advice, anyone?

Thanks,

The Eternal Squire