The harmonica is "the accordion of the soul," said Bud Gardner, founder of the Sun City Harmonicoots. Last year Gardner and the Harmonicoots, made up of 60 people from the Sun City retirement community, wrote a letter convincing the Society for the Advancement and Preservation of Harmonicas (SPAH) to hold the Harmonica Convention in Sacramento. The convention, now in its 46th year, began Tuesday and continues every day through Saturday at the Radisson Hotel. It features harmonica concerts, lectures and sales as well as impromptu (and scheduled) jam sessions. The convention will be continued next year in Milwaukee. "All four of the major harmonica manufacturers are here: Hoener, Sydel, H