uls-tracker
Sign in
Confidence: Medium · Source: FCC ULS · As of 2026-09-12

N6UFS callsign genealogy

Currently held by Castro, Mario 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 N6UFS's current licensee, walking backwards.

  1. KM6KDLcancelled· T
    Castro, Mario ACAgranted 2017-04-26cancelled 2017-12-27

Successor callsigns

Callsigns held now by people who previously held N6UFS.

No current licensee on record previously held this callsign.

All historical holders

Every license row we've seen with the callsign N6UFS, oldest first.

  • CASTRO, MARIO A CA
    1989-01-31 → cancelled 2001-02-01
  • Castro, Mario A CA
    2017-12-27 active