Hi Patrick,
Sorry that I forgot about your schematic request, however sometimes other things
in life take precedence. *The following files contain a description and a
simplified schematic of the HP AM Demodulator that I was talking about.
http://www.fmamradios.com/HP_AM_Demo...PJ-979-P14.jpg
The AM distortion is claimed to be less than 0.1%, although this article doesn't
say what modulation depth this is good to. *IIRC the service manual contains
those details. *I believe that the łaudio˛ bandwidth of this detector is
something on the order of 250 kHz. *I have a copy of the relevant pages from the
service manual somewhere around here, with a detailed schematic and parts list,
however I am not going to try and dig it out, the simplified schematic should
suffice to convey the basic idea. *The specs as to modulation depth vs.
distortion are probably also in the relevant HP catalog, I believe some of these
old HP catalogs are available on line, although I don't have any links to hand.
Thanks for all those links, but the schematics are not simply
explained or detailed and use more parts than I do and don't use tubes
and I'm not attarcted to trying out anthying they show. Most of it is
about FM detection.
Nothing is there that is specifically worked right out for a simple
old superhet with 455kHz.
My CF detector is looking real good to me.
Patrick Turner.