We are told ...
This Polish company has its origins in the Kasprzak radio manufacturer in the Wola district of Warshaw that was founded in 1951 on the basis of the old Philips Wola manufacturing plant and took over the produce of the AGA Radio from Diora Świdnica although there was parallel production for a short while. The company's name was formally “Zaklady Radiowe im. Marcina Kasprzaka w Warszawie” but that translates roughly as “The Warshaw Marcin Kasprzak Radio Manufacturing Plant”, and the company was named after Marcin Kasprzak, but he was a Polish revolutionary that was hanged in 1904 for killing 4 policemen a year earlier but later martyred by the communist government of post-WWII Poland.
The company started manufacturing radios of its own design in 1953 and introduced Poland's first commercially manufactured tape recorder in 1958 and the first car radio receiver a year later. Their tape recorder products became quite well known in the west during the 60's due to their keen price, some of them sold under their own ZRK (Primarily in Eastern Europe) or ZK names but more frequently as an OEM producer with products sold under a variety of names including Marconi and Ferguson, some of these tape recorder actually were designed by German company Grundig and in the 70's when open reel tape recorder sales began to slow Grundig actually moved their production to the ZRK factory.
The company became part of Unitra union at some point in the 1950's but their products usually kept on being branded ZK until the foundation of PHZ Unitra in 1972, in the west at the least, but after that most of their consumer products appear using the Unitra brand. The company was liquidated in the economic reforms of the early 90's as it was thought that it would never be able to compete in a market economy and the old factory has been refurbished and turned into an office block.