Confidence: Medium · Source: FCC ULS · As of 2026-09-14
W9NDU callsign genealogy
Currently held by KATZNELSON, BARRY J
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 W9NDU's current licensee, walking backwards.
- KATZNELSON, BARRY Jcancelled 1999-05-12
Successor callsigns
Callsigns held now by people who previously held W9NDU.
No current licensee on record previously held this callsign.
All historical holders
Every license row we've seen with the callsign W9NDU, oldest first.
- MARCOWITZ, HARRY IL1996-07-24 → cancelled 1999-03-17
- KATZNELSON, BARRY J IL2019-02-21 active