Sure - but remember, the OP is using the SB-220 on the CW/TUNE setting, so the output might be 600 watts on a good day. According to the chart, the Cantenna is good for at least 10 minutes at that level, with mineral oil. IMHO, tuneup shouldn't take more than 30 seconds or so. Fun fact: The Globar resistor in the Cantenna comes in two versions - one is coated to resist oil, and the other isn't. Homebrewers take note! IMHO, it all depends on what the dummy load will be used for. What amateur application requires dissipating large amounts of RF for more than a few minutes at a time?