PYE (Cambridge England) Mod. P240 YEAR 1966.

It's a 24 Inches (59Cm) B/W television from PYE an electronics company founded in Cambridge, England . Now Defunct !

It has manual preselection of tuning via rotary switch on the back for VHF and UHF Channels.

Television receivers currently being manufactured for consumer use were capable of operation in either the VHF (very high frequency) or UHF (ultra high frequency) bands of frequencies. In order to provide this capability, however, it is necessary to include two separate tuners or tuning circuits in the television receiver with one of these circuits being utilized for VHF reception and the other being used for UHF reception. The VHF tuner conventionally is a turret type of tuner having 13 detented positions which accomplish the coarse tuning or channel selection of the VHF tuner and a separate control is provided to effect the fine tuning at each of the channel positions. Generally, mechanical channel selecting devices for VHF television tuners fall into two groups, namely, the rotary-switching type or the turret types. Turret type tuners include an incrementally rotatable channel selector shaft for selectively connecting certain ones of a plurality of tuned circuit elements to each of a plurality of channel selector positions. UHF tuners generally employ a separate control mechanism or a tuning knob and use a dial indicator of a type commonly found in manual radio receivers. UHF tuners for television receivers are usually of a continuous tuning type similar to the tuning system adapted for radio sets. Therefore, the tuning in UHF channels has been extremely difficult as compared to the tuning in VHF channels. Such continuous tuning systems for the UHF tuners has heretofore been sufficient, since only two or three UHF channels have been authorized in one locality. However, where more UHF channels, namely seven or eight channels, are available for reception, a non-continuous type UHF tuner, which enables simpler tuning operation, is desired. Nevertheless, this continuous tuning system has heretofore been satisfactory, because there were only 2 or 3 UHF band channels or stations available for reception in an area. However, where there are an increased number (7 or 8 or more, for instance) of UHF band channels or stations available for reception, a non-continuous or intermittent tuning system as is adopted for the VHF tuner is preferable.

More desirably, the fine tuning control is presettable, so that the desired channel may be readily selected by merely turning the main channel switch-over shaft. The use of two separate tuning control mechanisms in order to effect the VHF and UHF tuning of the receiver is  at best; and when a receiver is provided with remote control capabilities, generally only the VHF band of frequencies may be remote controlled and the UHF channels still must be selected manually at the receiving set location.Conventional turret tuners still leave room for improvement, especially as far as minimizing the tuner size and dimension, and simplifying the assembly, as well as lowering the manufacture costs and improving the tuner performance are concerned.


This is a fully Electronic tubes technology chassis.

The B/W Tubes Television set was powered with a External Voltage stabiliser unit for Television (portable metal box) which relates to voltage regulators of the type employed to supply alternating current and a constant voltage to a load circuit from a source in which the line voltage varies. Such regulators are frequently provided employingConventional AC-operated television receivers exhibit several undesirable performance attributes. For example, under low-line voltage conditions such as those encountered during peak load periods or temporary power brown-outs imposed during times of power shortage, picture shrinkage and defocusing are encountered and under extreme brown-out conditions the receiver loses synchronization with a resultant total loss of picture intelligibility.

On the other hand, abnormally high-line voltage conditions are sometimes encountered, and this can lead to excessive high voltage and X-ray generation. In addition, either abnormally high steady state line voltage conditions or high voltage transients such as those encountered during electrical storms or during power line switching operations may subject the active devices and other components of the receiver to over-voltage stresses which can lead to excessive component failure.

It is a principal object of the present invention to provide a new and improved AC-operated television receiver having greatly improved performance characteristics in the presence of fluctuating power supply voltages.

A more specific object of the invention is to provide an AC-operated television receiver affording substantially undegraded performance under even extremely low-line voltage conditions without excessive high voltage and X-ray generation under even extremely high-line voltage conditions.

Still another and extremely important object of the invention is to provide a new and improved AC-operated television receiver having greatly improved reliability against component failure. saturable core reactors and condensers connected in circuit...  in such manner as to provide a plurality of variable voltage vectors which vary in different senses, as the line voltage varies, but which add vectorially in such manner that the
voltage stabilization
is automatically effected by the provision of an inductive pilot control device which is adapted to provide two excitation supply voltages for producing excitation or satuation of two magnetic circuits of a reversible booster transformer unit or units and diversion of flux from one magnetic circuit to the other, the booster unit being energized by primary windings from the A. C. supplysystem and being provided with a secondary winding or windings connected between the supply system and the corresponding inain or distribution circuit and in series therewith, through which a corrective boost voltage is
introduced into the circuit under the influence of the pilot control device, of an amount equal to that of the supply voltage fluctuation which initiated it and appropriate in polarity and direction for restoring the voltage to normal value and providing automatic stabilization of the circuit voltage against supply voltages which fluctuate above and below normal value.

Their vector sum remains substantially constant upon variations in line voltage, for providing automatic voltage stabilization of single or multiphase A. C. circuits where the supply voltage and frequency are subject to variation above and below normal value and where the load is subject to variation between normal limits.
The pilot control device which may be employed singly or may comprise three units or their equivalent when applied to multiphase supply systems comprises a pair of closed magnetic circuits or cores constructed of strip wound magnetic material or stacked laminations, the two
circuits forming a pair being constructed of materials possessing dis~similar magnetic characteristics when jointly energized by identical windings in series or by a collective primary winding, the said magnetic circuits being suitably proportioned to provide equal fluxes when energized at normal voltage.

The pilot control device is provided with a main and an auxiliary secondary winding or group of windings, the main secondary winding or windings being adapted to provide a voltage representing the difference in the fluxes of the two circuits to which it is jointly associated, while
the auxiliary secondary winding embraces only one circuit, preferably that subject to the least amount of flux variation. Either of the windings consists of two equal sections or in effect a double winding with a center tapping to which one end of the single winding is connected.

The voltage in the single secondary winding of the pilot device becomes directionally additive to that in one half of the tapped secondary winding a nd substractive in respect to that in the other half. When the supply voltage is normal the voltage provided by the single secondary winding is zero, since there is no difference of flux in the two magnetic circuits, and the two excitation voltages
produced in the halves of the other secondary winding are equal and when connected to the two excitation windings of the booster units, do not produce any diversion of flux between the two circuits or sets of circuits in the magnetic system of the booster transformer unit become equal, and since the series winding on the booster unit is arranged to provide a voltage due to the difference of
the fluxes in its two magnetic circuits or sets of magnetic circuits, no corrective voltage is introduced into the main circuit by the booster. If, however, the supply voltage varies from normal the pilot control device provides a voltage across the one secondary winding due to the difference in the fluxes of the two dis-similar magnetic circuits of which it is comprised, which voltage is combined with thosc in the halves of the other secondary winding to provide two excitation voltages which vary complementarily to each other as the supply voltage fluotuates, and cause a transference of flux between the two
circuits or groups of circuits in the booster unit and automatically provide a corrective boost voltage in the main circuit in which the series winding of the booster transformer is included of a value equal to that of the variation in supply voltage which initiated it.
The pilot device may be arranged in various ways, forboth single phase and multiphase operation, as exemplified by the constructions hereinafter more fully described.Similarly, numerous arrangements of the booster transformer unit are possible, some of which are hereinafter described in detail. The booster transformer unit embodies thc principles of the inductive devices described in my co-pending Application No. 411,189, filed February 18, 1954.

As an alternative to the provision of an auxiliary secondary winding on the pilot control device this may be
replaced by an independent or external source of supply,which may be either subject to or independent of supply voltage variation, provided such supply may be arranged with a center tapping if required.

Feed-back arrangements may be employed for providing compensation against voltage drop due to the effects of load in various ways. These are preferably providedon the booster transformer unit and may comprise a current transformer in one or more lines of the main circuit,
the secondary output of the transformer being rectified and arranged to energize an additional excitation winding on the booster transformer unit which in clfect increases the amount of the corrective boost voltage as the load increases.



Pye Ltd. was an electronics company founded in Cambridge, England and is currently wholly owned by Philips.

W.G. Pye & Co. Ltd. was founded in 1896 in Cambridge by William George Pye, an employee of the Cavendish Laboratory, as a part time business making scientific instruments. By the outbreak of World War I in 1914 the company employed 40 people manufacturing instruments that were used for teaching and research. The war increased demand for such instruments and the War Office needed experimental thermionic valves. The manufacture of these components afforded the company the technical knowledge that it needed to develop the first wireless receiver when the first UK broadcasts were made by the BBC in 1922. Instruments continued to be designed and manufactured under W G Pye Ltd, later situated in York Street Cambridge, while a separate company was started to build wireless components in a factory at Church Path, Chesterton.
A series of receivers made at Church Path and were given positive reviews by Popular Wireless magazine. In 1924 Harold Pye, the son of the founder, and Edward Appleton, his former tutor at St. John's College, designed a new series of receivers which proved even more saleable. In 1928 William Pye sold the company, now renamed Pye Radio Ltd., to C. O. Stanley, who established a chain of small component-manufacturing factories across East Anglia.
When the BBC started to explore television broadcasting, Pye found that the closest of their East Anglian offices was 25 miles outside the estimated effective 25 mile radius of the Alexandra Palace transmitter. Stanley was fascinated by the new technology and on his instructions the company built a high gain receiver that could pick up these transmissions. In 1937 a 5-inch Pye television receiver was priced at 21 guineas (£22.05) and within two years the company had sold 2000 sets at an average price of £34.
The new EF50 valve from Philips enabled Pye to build this high gain receiver, which was a Tuned Radio Frequency (TRF) type and not a superhet type. With the outbreak of World War 2 the Pye receiver using EF50 valves became a key component of many radar receivers, forming the 45 MHz Intermediate Amplifier (IF) section of the equipment. Pye went on to design and manufacture radio equipment for the British Army, including Wireless Sets No. 10, 18, 19, 22, 62 and 68.
In February 1944 Pye formed a specialist division called Pye Telecommunications Ltd which it intended would design and produce radio communications equipment when the war ended. This company developed, prospered and grew to become the leading UK producer of mobile radio equipment for commercial, business, industrial, police and government purposes.
See http://www.pyetelecomhistory.org
(Please note:- The collection at the site aforementioned does not have any information on Pye or Philips domestic broadcast radio, television or audio equipment - this collection consists only of military and professional two-way radio communications equipment.)

After the war Pye's B16T 9-inch table television was designed around the 12-year-old EF50 valve. It was soon superseded by the B18T, which used an extra high tension transformer (EHT) developed by German companies before the war to produce high cathode ray tube voltages.
In 1955 the company diversified into music production with Pye Records. The Independent Television Authority (ITA) started public transmissions in the same year so Pye had to produce new television designs that could receive ITV and the availability of a second channel introduced the need for tuners. Pye's V4 tunable television was launched in March 1954 and was followed by the V14. The V14 proved to be technically unreliable and so tarnished the Pye name that many dealers transferred their allegiance to other manufacturers. This failure so damaged corporate confidence that Pye avoided being first to market thereafter, although they developed the first British transistor in 1956. Pye TVT Ltd was formed to produce broadcast television equipment, including cameras which, as well as international sales, were very popular with British broadcasters including the BBC. The early cameras were called "the Photicon" and the later ones by their Mk number 2, 3, etc. The Mk7/8 solid state monochrome cameras were the last ones produced. The Pye Mk6 Image Orthicon camera was the last version supplied to BBC Outside Broadcasts in 1963 for a new fleet of eight outside broadcast vans. The ITV companies purchased the popular Pye Mk3s, and to a lesser extent the Mk4s and Mk7s. Unfortunately, Pye (TVT) never made it into producing a colour broadcast television camera but there was an abortive colour telecine camera; few if any were sold. The reason for this was probably the financial difficulties the company was in.
In 1979 PYE were implicated in an episode of Granda's World In Action in relation to the sale of UHV and VHF radios as well as telephone intercept equipment which was used in the Public Safety Unit's genocide of many Ugandans. [World In Action: Inside Idi Amin's Terror Machine first broadcast first broadcast 13 June 1979]

Not wishing to risk further damage to their fragile brand, Pye first used transistors in a product sold as a subsidiary brand: the Pam 710 radio, with the transistors themselves labelled Newmarket Transistors (another subsidiary). When this proved acceptable the company launched the Pye 123 radio a Pye 123 (still with the Newmarket label on the novel internal components). Products such as these reversed the decline but the arrival of Japanese competition reduced demand to a level that threatened the viability of the manufacturing plants. The company, like most of its domestic competitors, attempted to restore demand with price competition and, where viable production exceeded demand, sold excess stock at loss-making clearance prices. This tactic has no strategic value and by 1966 Pye was in such difficulties that they started to reduce their manufacturing capacity with closure of the EKCO factory in Southend-on-Sea.
Philips attempted to buy out the ailing Pye in 1966. The Trade Secretary Anthony Wedgwood Benn determined that a complete sale would create a de facto monopoly so he permitted the transfer of just a 60% shareholding with an undertaking that the Lowestoft factory would continue to manufacture televisions.
On 20 April 1964, BBC2 was launched, broadcasting entirely on the new television standard of 625-line UHF, but BBC1 and ITV would remain in 405-line VHF until 1969, so, until 1971, all television receivers in the UK had to handle both the VHF and UHF wavebands. This added to the cost of producing television sets. The price of buying a dual-standard set, combined with the small coverage of BBC2 and the highbrow programming on that channel, meant that initial sales of dual standard sets were slow. The VHF system was finally switched off in the UK on 3 January 1985.
The arrival of 625-line UHF & PAL colour television in the mid sixties was not the rescue that domestic manufacturers had hoped. Test signals began in 1966 and scheduled transmissions commenced on BBC2 on 1 July 1967, with a full colour service beginning on that channel on 2 December 1967. BBC1 and ITV followed suit on 15 November 1969.
The arrival of colour broadcasting in the UK added further to the cost and complexity of producing television sets. The resulting high price and low coverage ares of the new technology delayed consumer adoption further. It wasn't until the TV licence year of April 1976 to April 1977 that the number of colour licences sold outnumbered those of black and white.
In the early 1970s Sony and Hitachi launched UK colour televisions that cost less than £200. Domestic manufacturers attempted to compete, but were handicapped by outdated manufacturing techniques and an inflexible workforce. Pye found themselves with high stocks and low cash flow at a time when industrial relations were poor, the economy was ailing and there was little scope for cost reduction. Foundering, the Pye group of companies was bought outright by Philips in 1976. The Lowestoft factory was subsequently sold to Sanyo and Philips moved the manufacture of Pye televisions to Singapore. Prior to the manufacturing offshoring, the company produced a range of televisions branded 'PYE Chelsea'. The range were teak clad with stainless steel 'feet' and sported three large channel selectors. Whilst unsuitable for the then upcoming 4th UK channel, the equipment would operate through early video recorders, machines with larger channel capability. The Chelsea range were popular with TV rental companies such as Radio Rentals, Rumbelows and Wigfalls. Maintenance of these sets continued well into the 1980s, with the northern rental chain Wigfalls being the last to withdraw them in 1988.
The PYE brand enjoyed a short-lived renaissance of audio equipment (known as music centres) during the 1970s and in the late 1980s with televisions, gaining something of a cult status among college students at the time.
In recent years the Pye brand has enjoyed a resurgence on the UK market, with domestic products including DVD recorders. The Pye brand is one of a handful surviving today from the early domestic electronics era that dates to before World War II.

A good point  on good  old  B/W Televisions.....................

The Sixties was a time of great change for TV. At the start of the decade there were just monochrome sets with valves, designed for 405 -line transmissions at VHF. By the end there was 625 -line colour at UHF, with transistorised chassis that used the odd IC.

The following decade was one of growth. The "space race" had begun in 1957, when the USSR launched Sputnik 1 and terrified the Americans. Thereafter the USA began to spend countless billions of dollars on space missions. This got underway in earnest in the Sixties, with the announcement that America would be going all out to get a man on the moon by the end of the decade. There followed the Mercury series of earth - orbit missions, then the Apollo launches. Success was achieved in 1969. Most of these missions were televised, and in those days anything to do with space was hot stuff. It was inevitable that everyone wanted to have a television set. At the time an average receiver would be a monochrome one with a 14in. tube - there was no colour until 1967. It would cost about 75 guineas. 
TV sets were often priced in guineas (21 shillings) as it made the price look a bit easier on the pocket. Anyway 75 guineas, equivalent to about £78.75 in 2000's currency, was a lot of money then.  For those who couldn't, rental was a good option. The Sixties was a period of tremendous growth for rental TV. 
Much else was rented at that time, even radios, also washing machines, spin driers, refrigerators and, later on, audio tape recorders (no VCRs then). 
For most people these things were too expensive for cash purchase. 
There were no credit cards then. And when it came to a TV set, the question of reli- ability had to be taken into account: renting took care of repair costs. 

TV reliability.........The TV sets of the period were notoriously unreliable. They still used valves, which meant that a large amount of heat was generated. The dropper resistor contributed to this: it was used mainly as a series device to reduce the mains voltage to the level required to power the valve heaters. These were generally connected in series, so the heater volt- ages of all the valves were added together and the total was subtracted from the mains voltage. The difference was the voltage across the heater section of the dropper resistor, whose value was determined by simple application of Ohm's Law. 
As valves are voltage -operated devices, there was no need to stabilise the current. So the power supply circuits in TV sets were very simple. They often consisted of nothing more than a dropper resistor, a half or biphase rectifier and a couple of smoothing capacitors. If a TV set had a transformer and a full wave rectifier in addition to the other components, it was sophisticated!
 As the valve heaters were connected in series they were like Christmas -tree lights: should one fail they all went out and the TV set ceased to function. Another common problem with valves is the cathode -to -heater short. When this fault occurs in a valve, some of the heaters in the chain would go out and some would stay on. Those that stayed on would glow like search- lights, often becoming damaged as a result. Dropper failure could cause loss of HT (dead set with the heaters glowing), or no heater supply with HT present. When the HT rectifier valve went low emission, there was low EHT, a small picture and poor performance all round. CRTs would go soft or low emission, the result being a faint picture, or cathode -to -heater short-circuit, the result this time being uncontrollable brightness. On average a TV set would have twelve to fourteen valves, any one of which could go low -emission or fail in some other way. All valves have a finite life, so each one would probably have to be replaced at one time or another. The amount of heat generated in an average TV set would dry out the capacitors, which then failed. So you can see why people rented! 

The CRT could cause various problems. Because of its cost, it was the gen- eral practice to place its heater at the earthy end of the chain. In this position it was less likely to be overloaded by a heater chain fault. But during the winter months, when the mains voltage dropped a bit, it would be starved of power. This would eventually lead to 'cathode poi- soning' with loss of emission. The 'cure' for this was to fit a booster transformer designed to overrun the heater by 10, 20 or 30 per cent. It would work fine for a while, until the CRT completely expired. At about this time CRT reactivators came into being - and a weird and wonderful collection of devices they turned out to be. Regunned tubes also started to appear. You couldn't do this with the `hard -glass' triode tubes made by Emitron. These were fitted in a number of older sets. Yes, they were still around, at least during the early Sixties.



Developments................... A great deal of development occurred during the Sixties. Many TV sets and radios made in the early Sixties were still hard -wired: the introduction of the printed circuit board changed the construction of electronic equipment forever. The first one was in a Pam transistor radio. PCBs were ideal for use in transistor radios, because of the small size of the components used and the fact that such radios ran almost cold. 
They were not so good for use with valve circuitry, as the heat from the valves caused all sorts of problems. Print cracks could develop if a board became warped. If it became carbonised there could be serious leakage and tracking problems. In addition it was more difficult to remove components from a PCB. Many technicians at that time didn't like PCBs. As the Sixties progressed, transistors took over more and more in TV sets. They first appeared in a rather random fashion, for example in the sync separator stages in some Pye models. Then the IF strip became transistorised. Early transistors were based on the use of germanium, which was far from ideal. 

The change to silicon produced devices that were more robust and had a better signal-to-noise ratio. 
Car radios became fully transistorised, and 'solid-state' circuitry ceased to be based on earlier valve arrangements. Many hi-fi amplifiers had been transistorised from the late Fifties, and all tape recorders were now solid-state. 
Both reel-to-reel and compact -cassette recorders were available at this time. Initially, audio cassette recorders had a maximum upper frequency response of only about 9kHz. 
To increase it meant either a smaller head gap or a faster speed. Philips, which developed the compact audio cassette and holds the patents for the design (which we still use in 2000!) wouldn't allow an increase in speed. Good reel-to-reel recorders had a fre- quency response that extended to 20kHz when the tape speed was 15in./sec. 
This is true hi-fi. In time the frequency response of compact -cassette recorders did improve, because of the use of better head materials with a smaller gap. 
This led to the demise of the reel-to-reel audio recorder as a domestic product We began to benefit from spin-offs of the space race between the USA and the USSR. 
The need to squeeze as much technology as possible into the early computers in the Mercury space capsules used by the USA lead to the first inte- grated circuits. 
This technology soon found its way into consumer equipment. Often these devices were hybrid encap- sulations rather than true chips, but they did improve reliability and saved space. The few chips around in those days were analogue devices.  To start with most UHF tuners used valves such as the PC86 and PC88. They were all manually tuned. Some had slow-motion drives and others had push -buttons. They didn't have a lot of gain, so it was important to have an adequate aerial and use low -loss cable..............................