cascade analysis paradox

I am using a free software tool for cascade analysis. http://www.spectrummicrowave.com/cascade.asp

I am using the SA636 for the second down conversion in my rx chain.

The problem is that the SA636 spec has a mixer that provides conversion gain instead of conversion loss.

The parameters for the mixer in the software does not allow you to enter a conversion gain for a mixer, only conversion loss.

Is there any free software out there that allows you to enter conversion gain for the mixer? Is there any way to get around this problem within this software?

Positive numbers are conversion gains, negative numbers are conversion losses..

The mixer parameter box only accepts positive numbers for conversion loss.

You can split the problem in to two section
One is mixer and amplifier (the other) in cascade.
Now you model this such that you get the mixer amplifier cascaded sage gives the same as the SA363

try Appcad

You can find the cascaded analysis under noise calc menu

Appcad from Agilent has what you need, plus some other goodies.