We used a calorimetric method to measure the microwave absorption of a high-mobility 2-dimensional electron gas in small magnetic fields. The calorimeter responded well to the signal, even when reduced to a single dot. Curiously, in the smaller dot lattices we found the zero-field plasmon resonances to be much less the than expected values; however a second, larger sample yielded better values. As a result of the high mobility of the sample we also saw evidence of the second harmonic of the plasmon frequency coupling with the cyclotron resonance, although a corresponding edge mode was not found. The calorimetric method appears to be a valid means of measuring signal absorption in a 2DEG and has potential for probing other types of systems.