Confidence: Medium · Source: FCC ULS · As of 2026-09-12
WU4D callsign genealogy
Currently held by CASTILLO, RENE R
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 WU4D's current licensee, walking backwards.
- CASTILLO, RENE RVAgranted 1999-05-24cancelled 2001-02-13
Successor callsigns
Callsigns held now by people who previously held WU4D.
No current licensee on record previously held this callsign.
All historical holders
Every license row we've seen with the callsign WU4D, oldest first.
- GRUOL, LESTER E NC1988-06-07 → cancelled 2000-06-09
- CASTILLO, RENE R VA2021-01-06 active