Personally, I prefer to use a square wave, or at least a strong sine wave
into any mixer....

The mixer itself is non-linear and so it will usually produce a number of
LO harmonics.

Driving the LO at a high level reduces the length of time the mixer is in
the 'semi-on/off' region as the LO transits through 0 VAC.

Generally speaking, that time near 0 VAC LO is where the mixer is most
prone to being overloaded and intermod products being created so a strong LO
drive usually results in somewhat better dynamic range for the mixer.

I plan on the filters before the mixer to keep signals at the LO harminoc
out of the mixer, and as noted in another posting, a simple lowpass will do
the trick in an upconverting Rx design.


Jim Pennell
N6BIU