Confidence: Medium · Source: FCC ULS · As of 2026-09-12
W4SDF callsign genealogy
Currently held by 304th Infantry Battalion, ALSDF
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 W4SDF's current licensee, walking backwards.
- Richter, Michael EKYgranted 2022-08-25cancelled 2022-11-26
Successor callsigns
Callsigns held now by people who previously held W4SDF.
No current licensee on record previously held this callsign.
All historical holders
Every license row we've seen with the callsign W4SDF, oldest first.
- 304th Infantry Battalion, ALSDF AL2007-06-05 → cancelled 2019-06-06
- Richter, Michael E KY2022-11-26 active