Author: Alan, 5B4AHJ

Callsigns of the format KA#xx can cause some confusion regarding which DXCC entity they are used from.

In the above format # is a numeric digit [0:9] and xx is two consecutive alpha characters [A:Z]

Confusion arises because two separate licensing authorities issued these calls, with an overlapping period when callsigns issued by both authorities were in use at the same time.

In the post-war period in the Pacific, many US service personnel, who were amateur radio operators, were stationed in Japan and the Philippines and were issued with KA#xx callsigns. Stations in Japan, Okinawa, Ogasawara and Minami Torishima using these callsigns were known as Auxilliary Military Radio Stations (AMRS), not to be confused with the Austrian Military Radio Society, also AMRS. AMRS stations were regulated by the Far East Auxiliary Radio League (FEARL), a military organisation.

Although the KA1 prefix was not allocated to AMRS it was used from Iwo Jima (KA1IJKA1IW) and Minami Torishima (KA1AAKA1BLKA1CGKA1DXKA1MCKA1MIKA1NC).

From March 1978, FCC started issuing KA#xx callsigns to radio amateurs in the USA, thus overlapping the use of KA#xx callsigns in Japan. 

The first KA#xx calls issued by the FCC were the KA1xx series, commencing in March 1978. These were later followed by KA0xx.

The table below shows how Club Log maps KA#xx callsigns:

ADIF Name ADIF DXCC No DXCC status Date Prefix
Philippines 375 Current 1946-48 KA[1-9] (also three-letter suffixes)
Ogasawara 192  Current  1950-59  KA0
Ogasawara 192 Current From 1968-06-27 until 1978-03-23 KA1
Minami Torishima 177 Current By exception KA1
United States of America 291 Current From 1978-03-24 KA[0-9]  (also three-letter suffixes)
Japan 339 Current From 1950-06-01 until 1978-03-23 KA[2-5, 7-9] 
Okinawa 193 Deleted From 1950-06-01 until 1972-05-15 KA6
Japan 339 Current From 1972-05-15 until 1978-03-23 KA6


  • KA#xx calls that do not conform to the above rules are handled by exceptions (eg calls from Japan after 1978-03-23).

References and acknowledgments

AD1C Jim Reisert

JJ1WTL site on the history of Japanese callsigns: JJ1WTL callsign.

K1ZZ David Sumner