If you can't hold your hand on it for at least ten seconds, it's likely too hot. FWIW, -John W7QHO at aol.com wrote: > All, > > Have worked on several 348s over the years but this is the first one with an > original dyno (DM-28-R). > How hot do these things get when operating at rated in/out voltage and > current? > > Thanks. > > Dennis D. W7QHO > Glendale, CA