Here's a small table with previous and present preffixes

1925
first and only wireless station R1FL from russia

since 1926
01-RA,02-RA...   personal radio
RA-01,RA-02,...  club stations
---------------
since 1929
EU1..9 - european USSR
AU1...9  - asiatic USSR
--------------
etc
...
...
since 1.05.1984
until 1993= since 1 jan.1993 till nowadays
-------------------------------------------------------
RN,UN,RA,RV,RW,RZ,UA,UV,UW,UZ=RA-RZ,UA...UI
RT,UT,RB,UB,UY=UR...UZ
RC,UC=EW,EU,EV
RD,UD=4K,4J
RF,UF=4L
RG,UG=EK
RH,UH=EZ
RI,UI=UK
RJ,UJ=EY
RL,UL=UN,UO,UP
RM,UM=EX
RO,UO=ER
RP,UP=LY
RQ,UQ=YL
RR,UR=ES
4K1=R1AN..
4K2=UA1 european part of Arctic ocean islands (incl. 4K2=R1FJ...)
4K3=UA9 asiatic part of Arctic ocean islands
4K4=UA0 far east part of Arctic ocean islands
UPOL.., 4K0=drifting polar stations
4K5=UA0F Kuril is
4J1=R1MV..
----------------------------------------------------------------
For example:
UN1AB in 1992 - Karelia, Russia
UN1AB now  - Kazakhstan

PS.
RK,UK =radioclub from anywhere above or below until 1 may 1984. Later as
Russia until 1993. Since 1993 as Uzbekistan

PPS.
EZ-call signs were used by 'novice' class stations since 22.march.1979 until
1.may.1984. Later
reserved. Now it belongs to Turmenistan...
EZ3A in 1983 - Moscow, Russia
EZ3A in 2000 - Ashgabad, Turkmenistan........

PPPS.
Some unusual calls are aired now:
U1,U2,U3,U4,U6,U9,U0=UA  WW2 veterans
U5=UR  WW2 veterans
RAEM=Krenkel memorial call (Moscow Russia)
U1MIR...U0MIR=space ships calls


The list of Russia oblasts (both old and new) is on my home site
www.qsl.net/rw4nm/
Best 73 & dx

de Andrei rw4nm