Confidence: Medium · Source: FCC ULS · As of 2026-09-12
AC4IO callsign genealogy
Currently held by METZLER, DONALD A
The FCC publishes a previous_call_sign on
every amateur license — a self-link to the licensee's prior callsign.
Following those links produces the chain below.
Previous callsigns
Older callsigns held by AC4IO's current licensee, walking backwards.
- KN4ZIno FCC ULS record on file
Successor callsigns
Callsigns held now by people who previously held AC4IO.
No current licensee on record previously held this callsign.