I remember doing something with one of AD's quadrature modulators, using an
AD9854 as the LO source. I came up with a circuit that would give 50dB
opposite sideband suppression from 4MHz to 1.5GHz. I don't know if Motorola
ever applied for a patent for that circuit. I guess that circuit could also
work. It sounds like you have taken a sound approach.

Pete

Jake Brodsky wrote in message
...
On Tue, 30 Dec 2003 07:08:46 GMT, "Pete KE9OA"
wrote:

I am not sure how to do the selectable sideband function, but I can
figure
it out, I will sure throw that function in.

On my bench as I type this is a nearly completed audio phase shift
network for KK7B's R2pro. It is designed for handling the 90 degree I
and Q phase shifts for audio from below 300 Hz to at least 4 kHz.

Yes, it uses 1% components for the resistors and capacitors. However,
it's built with commonplace operational amplifiers. With just an
amplitude balance pot, one should be able to achieve opposite sideband
rejection ratios of at least 50 dB. If you really want to get the
very best out of it, one could reach rejection ratios of 60 dB, though
KK7B says that maintaining this performance over typical room
temperature shifts is probably more trouble than it's worth.

To put this sort of performance in perspective, most consumer SSB
receivers audio noise floors would mask the opposite sideband.


Jake Brodsky, AB3A
"Beware of the massive impossible!"