I received a QSL for my reception of RCN Cartagena on 1000 kHz. I heard this station, and the RCN stations from Medellin (990 kHz) as well as Cali (980 kHz) while staying on Curacao. Unfortunately the response was a poorly detailed answer via facebook messenger only.
The structure of the Radio Cadena Nacional organisation in Colombia is quite complicated with national and regional production centers and various network programs. On medium wave RCN as I heard it on 1000 kHz is their main program.
Antena 2 is their second network broadcasting sports. Antena 2 has dedicated frequencies in Bogotá, Cali and Medellin, but in other cities it shares the frequency with La Cariñosa. The latter is a network program started in 2000, focusing on popular music.
I came also across RCN owned Radio Red network (for example Bogotá, 970 kHz). Until 2013 these frequencies belonged to Cadena Super. The station I heard from Medellin (710 kHz) is referred to as Cristal Radio Red, but is in fact part of the same network.
Finally I received a “stand alone” RCN station called Años Maravillosos from Bogotá on 1340 AM. This seems a “left over” of the Amor Radio network which had several stations on FM. The FM stations have all been transitioned to other “FM only” networks of RCN: La Mega, La Uno and La FM.