In a 24-hour blitz that will include nationwide communications, the Elmhurst-based York Radio Club will operate at least three radio stations from the Elmhurst Fire Department Training Facility, 910 N. Addison, on Saturday and Sunday, June 27-28. The operation will be part of Amateur Radio Field Day, an annual contest started in 1933 that is designed to test emergency preparedness. In past years, more than 30,000 Amateur Radio operators in the United States and Canada have taken part. Visitors interested in learning more about the ham radio hobby, or those who are simply curious, are welcome. The operation will include a small solar power demonstration, as well as digital technology that combines computers with ham radios.