Confidence: Medium · Source: FCC ULS · As of 2026-09-14
W1SDN callsign genealogy
Currently held by Donovan, Sean P
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 W1SDN's current licensee, walking backwards.
- Donovan, Sean PGAgranted 2013-08-30cancelled 2015-11-17
Successor callsigns
Callsigns held now by people who previously held W1SDN.
No current licensee on record previously held this callsign.
All historical holders
Every license row we've seen with the callsign W1SDN, oldest first.
- THOMAS, RALPH G FL1997-12-09 → cancelled 2009-12-10
- Donovan, Sean P DC2025-09-03 active