Hi
On Sun, 24 Oct 2004 14:30:59 -0700, The Eternal Squire
wrote:
Hi,
I've been trying to build my first superhet but I have been having problems.
snip details
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
Some wild guesses g
- not enough decoupling on the 9v rail of the audio power amp (a
couple of hundred uF's as close as possible to the chip)
- speaker leads running too close to the inputs to the x100 amp
- try running the x100 board at less than 9v (anything from some
resistance and a decent electrolytic in the 9v line up to some
'proper' voltage regulation)
- some kind of an earth loop ? - if the board are connected by coax
try lifting the braid at one end of the cable
Hope these help ....?
Adrian
Suffolk UK
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