NORSK RADIOFABRIKK

The Norwegian Radio Manufacturing Company

The company was founded in 1979 by Espen Evensberget, Paal Rasmussen and myself. 

I will come back with more info on this later, but for now, see what the press said at the time:

Danish High Fidelity no. 2 1981

Hi-Fi & Elektronikk no. 2 1980

Hi-Fi & Elektronikk no. 5 1980

Musikkavisen PULS no.2 1980

Musikkavisen PULS no.4 1980

And read the company's own press release "Tre Faser i en Utvikling" about the story of the Otala power amplifier including the NRF modifications, written in 1979.