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Confidence: Medium · Source: FCC ULS · As of 2026-09-14

KR4OK callsign genealogy

Currently held by ALDERFER, JEFFREY M

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 KR4OK's current licensee, walking backwards.

  1. K3JMAcancelled· A
    ALDERFER, JEFFREY MNCgranted 2008-04-22cancelled 2008-12-23

Successor callsigns

Callsigns held now by people who previously held KR4OK.

  1. K3JMAcancelled· A
    ALDERFER, JEFFREY MNCgranted 2008-04-22cancelled 2008-12-23
  2. WA4JMAcancelled· A
    ALDERFER, JEFFREY MNCgranted 2000-10-17cancelled 2001-08-25

All historical holders

Every license row we've seen with the callsign KR4OK, oldest first.

  • ALDERFER, JEFFREY M NC
    1994-03-08 → cancelled 2000-10-17
  • ALDERFER, JEFFREY M NC
    2003-11-01 → cancelled 2008-04-22
  • ALDERFER, JEFFREY M PA
    2018-09-25 active
← Back to KR4OK License history →