Benitez,
It will help to know the manufacturer of the radio and a model number or other numbers on the radio chassis or case.
Radiodoc
Benitez,
If there are no markings on the radio such as model number or chassis numbers. Look at the parts on the chassis for a name. Also look on the tubes to see if there is a manufacturer name common to all or most of the tubes. This may help identify possibly who made the radio. It is possible say if most of the tubes were RCA tubes, the radio may be of RCA manufacture and possibly looking under reference of this manufacturer find a schematic for it. Possibly posting a picture of the radio and providing us with the link to the picture may also help with identification.
Radiodoc