Confidence: Medium · Source: FCC ULS · As of 2026-09-14
KO9S callsign genealogy
Currently held by Schellhorn, Nikolaus
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 KO9S's current licensee, walking backwards.
Successor callsigns
Callsigns held now by people who previously held KO9S.
No current licensee on record previously held this callsign.
All historical holders
Every license row we've seen with the callsign KO9S, oldest first.
- COIL, ALLEN L WI2008-07-04 → cancelled 2020-08-05
- Schellhorn, Nikolaus CA2020-09-09 active