A local oscillator is local, that is -- it is an oscillator in the receiver
that generates a signal to heterodyne (beat) with the incoming signal to
produce plus and minus difference signals, the minus usually being the
Intermediate freq (IF). See URL:
http://www.see.ed.ac.uk/~gjrp/EE3/Co...re6/sld005.htm

" As an example, if I wanted to make a single frequency receiver could I
just use an external fixed oscillator for the LO signal?

Yes many a superhet has a fixed LO particularily VHF and up older designs --
used xtal or xtals -- with a crystal oscillator circuit for stability, but a
tuneable LO or now a days a synthesixed LO is more common.

Have fun


"Liam Ness" wrote in message
...
I am trying to get a handle on superhet design and keep getting stuck
on the local oscillator portion. I've been wading through the ARRL
handbook and some other resources, but I can follow exactly how the LO
signal is created. Is the signal generated entirely in the radio, or
is the signal generated from the RF picked up from the antenna, or am
I so off base that neither explaination is right?
As an example, if I wanted to make a single frequency receiver could I
just use an external fixed oscillator for the LO signal?

TIA

Liam