The identification for this radio is found on the dial. In the center it shows the text "R.R. RADIO" and in the lower right corner the word "STANDARD".
In a Belgian magazine on historical radio the origin of the name is explained. "R.R." refers to Mr. Roy and Mr. Revol who cooperated in the development of radio equipment in Belgium since the beginning of the early twenties.
An advertisement on their 1936 cataloque is depicting the cabinet of a radio exactly the same as mine and is indicating the model number 640. The original price of this radio was 975 Belgian Francs. It is quite likely that the first digit of the model number refers to the year of origin (1936). All models in a 1937 advertisement have the "7" as the first digit. For almost all models the second digit relates to the number of tubes used (this does not apply to my model 640 !).
According to the official catalog of the 10th Radio Exhibition ("Salon de la T.S.F.") in Brussels in 1938, the company R.R. Radio, S.A. (address 44-46, rue de Goujons, Brussels) is one of the exhibitors. This company is still doing business from the same address in 1949, as can be seen in the catalog of the 13th "Salon de le Radio" in Brussels.

    Dial of R.R. RADIO

This R.R. Radio employs 5 tubes (2A5, 2A7, 2B7, 58 and 80), covers two bands and the wooden cabinet measures (hxwxd) 42x38x28 cm.
The chassis has a military-like green colour.

I am very much interested in more information about this radio (schematic etc.).

The radio (acquired on a radio flea market) had the following main defects:
1. volume potentiometer burnt out (so I don't know its value)
2. two open-circuit windings in an RF transformer.

Restored chassis. The tubes are not yet put back on place and the volume control is still missing.