Confidence: Medium · Source: FCC ULS · As of 2026-09-12
KC4FSU callsign genealogy
Currently held by Duffy, Joseph C
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 KC4FSU's current licensee, walking backwards.
- Duffy, Joseph CFLgranted 2019-05-07cancelled 2019-05-25
Successor callsigns
Callsigns held now by people who previously held KC4FSU.
No current licensee on record previously held this callsign.
All historical holders
Every license row we've seen with the callsign KC4FSU, oldest first.
- Harris, Ryan C FL2003-02-05 → cancelled 2015-02-06
- Duffy, Joseph C FL2019-05-25 active