Diffrential pair circuit analysis in Pspice
To achieve some &quot;comparator&quot; action, make R1 and R2 about 1 ohm.
And bias the PNP into linear region when the diffpair is balanced; try 0.6v/2mA = 300 ohms, for R7.
But this assumes you do want a COMPARATOR action.
You can explore some hysteresis, by inserting a 100,000 ohm resistor from output collector to any internal (internal to diffpair) positive_feedback point.