Confidence: Medium · Source: FCC ULS · As of 2026-09-12
KC1SOW callsign genealogy
Currently held by Klemm, Mark S
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 KC1SOW's current licensee, walking backwards.
- Klemm, Mark SNHgranted 2025-05-30cancelled 2025-09-20
Successor callsigns
Callsigns held now by people who previously held KC1SOW.
- Klemm, Mark SNHgranted 2025-05-30cancelled 2025-09-20
All historical holders
Every license row we've seen with the callsign KC1SOW, oldest first.
- Klemm, Mark S NH2023-03-03 → cancelled 2025-05-30
- Klemm, Mark S NH2025-09-20 active