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Newmarket Semiconductors

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Newmarket transistors Newmarket Transistors Ltd., usually referred to as NKT, and located in the Suffolk town famous for its racecourse, was one of the more idiosyncratic, and therefore interesting, small UK manufacturers of germanium transistors in the 1950's and 1960's. The original company "The Transistor Development Company" was formed in December 1953 as a wholly owned subsidiary of Pye Ltd., to 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. Intriguingly, they were true to their name and, to my knowledge, never made a single diode. Their logo seems to have changed a few times, possibly with the name changes, although they never printed a stylised logo on their transistors, the earliest types having no branding at all, and the later ones using the 'NKT' prefix.

Newmarket transistors Ltd Newmarket seem to have been quite successful in the germanium transistor business, judging by the number of different types that they manufactured. Their earliest devices are the V-series, then they changed over to the NKT series, and finally they made a number of Proelectron and other registered types in various series, including silicon types and FETs (although these may have been sourced elsewhere). They also made packaged circuit boards and even custom hybrid microcircuits in DIL and TO-99 packaging.

Unlike most UK germanium transistor manufacturers, NKT did survive the transition into the world of modern electronics, albeit at the cost of losing its original identity. Its direct successor still exists in the guise of Micro Circuit Engineering which specialises in the design, manufacture and testing of custom electronic components and sub-systems, including Application Specific Integrated Circuits, Custom Electronic Modules, Standard Components, Packaging of Microsystems and Ruggedised Displays.

Newmarket Pye If you know anything about Newmarket, or have other information about NKT's early semiconductors, please

I do not possess all the transistors below, in fact I am seeking many of them. It is noted in the text where I am seeking examples of any particular type: if you have some for sale or exchange, please Conversely, I am happy to help anyone looking for information on these devices. I have an extensive collection of original data sheets and books, and can provide characteristic data on almost all Newmarket types.
V6 transistors V10 transistors The first commercial Newmarket devices were junction types in 1956: the red-painted V6 trio: V6/R2, V6/R4 and V6/R8, and the the green-painted V10 trio: V10/15, V10/30 and V10/50. These were very limited in performance: the V6 types were IF/RF transistors with a maximum collector-base voltage of 6 volts, and the V10 types were AF transistors with a maximum collector-base voltage of 10 volts. The three types in each trio were distinguished by gain selection, although there was considerable overlap between types according to contemporary NKT data books.
V10/15 in envelope These early types are occasionally found in paper envelopes as shown, with handwritten characteristics. Presumably these were prepared at the factory as specially-selected devices for critical applications. If anyone knows more about this, please

These transistors are of particular historic interest because they were used in the Pam 710, the first British transistor radio. However, it had one oddity: it appears to have used a red V6/R3, a type that is not mentioned in any contemporary data book. If anyone knows more about this, or has such a transistor, please
later V6 transistors It seems that the limited performance of the early V6 and V10 types was of concern, because in about 1958 Newmarket issued unpainted versions with a higher maximum power dissipation. The modified V6 types were distinguished by reversing the two characters of the gain banding, creating types V6/2R, V6/4R and V6/8R. The improved V10 series was identified by a suffix A. According to Newmarket literature, all the improved types were also available in a cylindrical can, with a further suffix C added, but I have never come across any transistors of this shape. If you have some, please
Spot-on transistors Like other manufacturers, Newmarket sold their out-of-spec low-power AF devices to the hobbyist market at reduced prices. This image shows a 'Spoton brand' transistor, marked as a 'yellow/green' type. I am unsure if these would have been of much use to anyone, they must have either had totally pathetic gain or else very high noise.
V30/10P transistor Newmarket did not in fact confine themselves to small-signal devices for radios but also released high-power AF types in 1956, using unusual 'stud' cans with a large bolt on the bottom and two pins for the other leads, still bearing part numbers indicating the collector voltage and current gain of the transistor. They came in three varieties: a few that I suspect are the earliest examples are simply black with a white part number, the majority have black/gold colouration, and late examples are completely unpainted. My image shows all three varieties for the V30/10P type.

The black body with gold painted top is significant: Newmarket used the branding 'Goltop' for many of its transistors. If anyone can explain the commercial reasoning behind this, please
V15/20IP transistor In 1959 Newmarket claimed to be first to release an "intermediate power" type of transistor: this image shows the top and bottom of the V15/20IP. The IP types, of which there are many with different voltage/gain values, used this circular domed can with a wide flange. In NOS condition they come with a mounting washer that clamps over the top and has two lugs with holes so that the transistor can be bolted to a heatsink. The image shows Goltop colouring: I also have some later IP types that are unpainted metal.
V10/1S transistor The bulk of the types in the V series were AF transistors, with the V6 IF/RF types being exceptional. In 1959 Newmarket announced two low-power switching types in the same oval SO-4 can: the V10/1S and V10/2S, also available in the cylindrical can with suffix SC. The oval V10/1S was used in the Ferranti Argus series of British process-control computers. I am seeking examples of the V10/2S, the V10/1SC and the V10/2SC. If you have any, please
noodle transistor Newmarket eventually made a few of the high-power V-series types in the standard TO-3 'diamond' can. For some strange reason, they initially gave them the suffix NP for 'noodle power' (yes, really, this is documented in their data books). If anyone can explain this unusual choice of characterisation, please My image shows a V15/30 in Goltop colours with a handwritten suffix NP (difficult to see on the small image). I have a number like that. Later on, they switched to the suffix DP, which I assume stands for 'diamond power', in an unpainted TO-3 can.
Newmarket's second series of transistors, the NKT series, became available in 1961 and developed into a very broad range of devices. I show a selection of them below.
NKT15 transistor The devices NKT1 to NKT99 are classified in the Newmarket 'Products Portfolio' (apparently dated 1962, although I suspect it is later) as germanium alloy PNP RF transistors with low maximum collector-base voltage, but the Portfolio only lists a small number of types in a standard TO-1 can, whereas I have many examples of types in the SO-4 oval can, such as the NKT15 shown, that are not listed. I suspect that the Portfolio shows a rationalised and very limited subset of the types actually produced during the early days of the series. If you can shed more light on this, please
NKT100 transistors The Portfolio describes the range NKT100 - NKT199 as germanium alloy PNP RF transistors with medium maximum collector-base voltage and again lists only a handful of types, this time in TO-5 cases, whereas I possess a selection of unlisted types in SO-4 oval cans, often with handwritten numbers. The image shows a uniquely black-painted NKT102, an NKT104, and a handwritten NKT152. I do have a solitary NKT128 in the TO-5 can.
NKT200 transistors The range NKT200 - NKT299 is described in the Portfolio as comprising germanium alloy PNP AF transistors, in TO-1 and TO-5 packaging. I possess a number in those standard cans, but also have several types in the oval SO-4. For reasons that are mysterious to me, one type in this range, the NKT275, seems to be regarded as the 'holy grail' of germanium PNP transistors by people who build guitar effects units using 1960's circuits. In terms of its characteristics, this is quite a poor device, with low collector-base voltage and a wide spread of low gains. I have been a huge fan of Hendrix since his first album, but I can't help thinking that he would have embraced new technology rather than slavishly copy obsolete circuits.
NKT300 transistors In the NKT300 range we break out into germanium PNP intermediate power types, some AF, some IF and some switches. These use the domed TO-8 can with screw-down washer, somewhat reminiscent of the V/IP types. I even have one example marked just '362' that uses the V/IP case, although this type number is not listed in the Products Portfolio.
NKT400 transistors The range NKT400 - NKT499 contained germanium PNP high-power types in TO-3 cans, both switching and audio devices. Many are unusual for TO-3 devices in that the diamond-shaped flange is not a solid integral part of the domed body but is made of thin metal cold-welded around the dome with a plastic former underneath.
NKT600 transistors The NKT600 range comprised germanium PNP alloy-diffused transistors in TO-8 cans, for VHF applications.
NKT700 transistors The NKT700 range contained all the NPN germanium transistors in the NKT series. It included both AF and RF types but all were low-power devices in TO-1 cans.
NKT PC3
The Product Portfolio also lists other types of device. These include
  • NKT10419 - NKT20339 silicon industrial transistors in TO-18 cans
  • NKT80111 - NKT80216 junction FETs in TO-17 and TO-18 cans
  • junction transistors in the ACY, BC, BCY, BDY, BFX, BFY, BSX and BSY series
  • junction transistors in the 2N series
  • packaged circuits PC1 - PC10 and PC101 - PC106
  • micro-miniature silicon active devices for direct attachment to film circuits
  • MC series custom microcircuits

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