"Fred Nachbaur" wrote in message
. ..

There may be more knowledgable folk who will differ, but it seems to me
that it's immaterial whether you amplify the RF directly, or after
conversion to a fixed intermediate frequency. The only real difference
is that in a superhet, tracking difficulties are greatly reduced because
you're dealing with only one frequency.


The biggest problem with TRF isn't the varying bandwidth, or even the
tracking.. but the tendency for feedback. The more stages you have at the
same frequency, the more likely it is that you will have feedback problems.
This is where the characteristic squeal and swishing sounds you hear
associated with very old radios come from. TRF's would break into
oscillation on a whim, unless each stage was very well shielded from all the
others. IIRC, this is how regenerative receivers were discovered/invented.