Confidence: Medium · Source: FCC ULS · As of 2026-09-12
N9BU callsign genealogy
Currently held by CASTLE, RICHARD M
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 N9BU's current licensee, walking backwards.
- HOLLMANN, LAWRENCE EINgranted 2021-04-26cancelled 2024-01-09
Successor callsigns
Callsigns held now by people who previously held N9BU.
No current licensee on record previously held this callsign.
All historical holders
Every license row we've seen with the callsign N9BU, oldest first.
- CASTLE, RICHARD M MI2011-09-22 → cancelled 2021-11-11
- HOLLMANN, LAWRENCE E IN2024-01-09 active