I powered it up with the variac. Alas the band switch is really tight and not functioning properly. I was able a couple of times to get it in just the right'spot' on 40 meters and did a quick tuneup on cw. Output was good near 100 watts, but the correct'spot' on the band switch was illusive. It's gonna need some help.
There could be other issues with the unit that are yet to be discovered. Will require maintenance sooner or later. The item "Vintage Heathkit SB-401 Ham Radio Transmitter for restoration 2956" is in sale since Tuesday, August 28, 2018.This item is in the category "Consumer Electronics\Radio Communication\Ham, Amateur Radio\Ham Radio Receivers". The seller is "raptor7x" and is located in Covington, Georgia. This item can be shipped to United States, Canada, United Kingdom, Denmark, Romania, Slovakia, Bulgaria, Czech republic, Finland, Hungary, Latvia, Lithuania, Malta, Estonia, Australia, Greece, Portugal, Cyprus, Slovenia, Japan, Sweden, South Korea, Indonesia, Taiwan, Belgium, France, Hong Kong, Ireland, Netherlands, Poland, Spain, Italy, Germany, Austria, Israel, Philippines, Switzerland, Norway, Saudi arabia, United arab emirates, Qatar, Kuwait, Bahrain, Croatia.