I'm messing around with a log converter (aka log amplifier) in LTSpice and am a bit stuck. I figured that a good place to start would be an application note or something so found this on the LM394 NPN "supermatched pair" datasheet:

The LM394 datasheet can be found here:
http://www.sycelectronica.com.ar/semiconductores/LM394.pdfWhen I put this circuit into LTSpice I get the following performance:

The red trace is Vout and the green trace is Vin. I have attached a ZIP file containing the LTSpice simulation.
The plot has Vin (V(n009)) as the horizontal scale, which is the input to the log converter and is a 1 Hz triangle wave going from 1 uV to 10 V. I expect to see a straight line (which would be the log of a triangle on a log scale) but I only see that for 3 decades. Has anyone got any idea why I only get log conversion after 10 mV?
I have built other variants such as the circuit in the SSM2212 datasheet and have the same problem - I can only get about 3 decades out of it. I am tempted to just build one and see if it works but I'd like to get the simulation working really.