I read in alt.binaries.schematics.electronic that Chuck Harris
wrote (in
) about 'MK484 single chip AM radio
question', on Fri, 8 Apr 2005:

Ahhh! Well, that changes everything. I took a look for the spec
sheet, and found the sheet for the ZN414Z, which is apparently almost
identical to the MK484. There are two things that I think would limit
operation at lower frequencies:

1) the gain appears to be purposefully rolled off at about 40KHz. That
is to say, it approaches zero at that frequency.

Yes, having found a 'data sheet' (handwritten), I see it has four
coupling capacitors between the stages. Not good news.

2) the detected audio stage has bandwidth out to 20KHz.

That may be controllable, but it's beside the point of there is no
useful gain at 20 kHz. In that case, a 741 would be usable, but a 709
would be better (small signals). (;-)
--
Regards, John Woodgate, OOO - Own Opinions Only.
There are two sides to every question, except
'What is a Moebius strip?'
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk