Complex sentence: In 1935, the Hammarlund Manufacturing Company introduced the first of the famous "Super-Pro" line after more than four years of planning and engineering: the SP-200 series, an 18-tube, single conversion superhet receiver.
Split into simpler sentences: In 1935, the Hammarlund Manufacturing Company introduced the SP-200 series, the first of the famous "Super-Pro" line. More than four years of planning and engineering went into producing the 18-tube, single conversion superhet receiver.