I re-measured the noise at TP7 using the Busby Low Noise Box and measured the instrument noise of the box - the noise is lower at high frequencies, but much higher at low frequencies. There is a possibility some of this came from old batteries - they measured 7.4 V, but we were 2 short in 40m so I couldn't replace them. I will try to get new batteries tomorrow and see if that affects it at all.

I also changed the couple of things that were wrong with the model and have the revised model as well as its resultant graph attached.

I subtracted the noise of the other amplifier from the previous measurement of the noise at TP7 and compared it with the new model and they line up almost perfectly except around 10 Hz, where they're a little off.