Newmarket Transistors Ltd. with its logo NK was located in Newmarket, Suffolk. It was an entire Pye subsidiary for manufacturing germanium transistors in the 1950's and 1960's. "The Transistor Development Company" was formed in December 1953 to develop and manufacture small signal low frequency germanium transistors for use in portable radios. In 1957 the company name was changed to "The Newmarket Transistor Company" and in 1958, it was changed again to "Newmarket Transistors Ltd". Newmarket did not make any point-contact transistors, their first commercial products were junction types released in 1956. The earliest types of transistors had no branding at all, followed by naming them "Yellow Circle" araound 1960, followed by a number 1 to 5 - see Pye model Q4. The later ones showed the NKT prefix.