I HAVE EQUIPPED THE STUNT BOXES IN MY 28'S ETC. TO RESPOND TO 'WA6ISGZW' (ACTUALLY 'ISGZW' SINCE THERE WERE NO OTHER DUPLICATES IN MY AREA) TO ACTIVATE MY ANSWER BACK UNIT... IT IS A STAND ALONE MECHANICAL SHOE BOX ANSWER BACK UNIT... ALSO WHEN IT RECEIVES MY CALL SIGN, IT PRINTS TILL 'NNNN'... THIS USES THE SOLENOID MENTIONED THE OTHER DAY BY SOMEONE... IT IS A FUN JOB BUT SOMEWHAT DETAILED...