Timer TimerGetAlarms= new Timer(new TimerCallback(TimerHandler), null, 500, 10000);

 

 private void TimerHandler(object state)
        {
            TimerGetAlarms.Dispose();
            TimerGetAlarms= null;
            this.Dispatcher.BeginInvoke((Action)delegate()
            {
                 //todo
            }

                );
        }