Confidence: Medium · Source: FCC ULS · As of 2026-09-14
W0BTB callsign genealogy
Currently held by Haselhorst Mr, Mark 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 W0BTB's current licensee, walking backwards.
- Haselhorst, Mark RCOgranted 2023-12-06cancelled 2024-01-09
Successor callsigns
Callsigns held now by people who previously held W0BTB.
No current licensee on record previously held this callsign.
All historical holders
Every license row we've seen with the callsign W0BTB, oldest first.
- Kucera, William F NE2005-08-30 → cancelled 2017-11-14
- Haselhorst Mr, Mark R CO2024-01-09 active