"matt weber" wrote in message
...

You can make a fairly respectable single conversion receiver, but
there are a couple things you need to do to get reasonable image
rejection, and selectivity. Raise the IF frequency to several Mhz, and
put a tuned rf amp in front of the mixer. That usually required a
crystal filter for good shape characteristics and good selectivity.


But if the IF is in the middle of the range of a wide coverage receiver, the
low bands will track backwards with respect to the oscillator frequency.
This can be dealt with by manually tuning the RF amp seperately or by
beating the tuning oscillator against a seperate oscillator and taking the
difference, which will track in the right direction.

Making single conversion radios with good image rejection is certainly
possible, but it isn't simple.


[snip]

Frank Dresser