Confidence: Medium · Source: FCC ULS · As of 2026-09-12
KB4FRX callsign genealogy
Currently held by KRAUTHEIM, WILLIAM A
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 KB4FRX's current licensee, walking backwards.
- Krautheim, William AFLgranted 2014-07-23cancelled 2015-09-15
Successor callsigns
Callsigns held now by people who previously held KB4FRX.
No current licensee on record previously held this callsign.
All historical holders
Every license row we've seen with the callsign KB4FRX, oldest first.
- KRAUTHEIM, WILLIAM A FL1997-05-14 → cancelled 2004-01-01
- Krautheim, William A FL2015-09-15 active