MAGNADYNE MOD. CR93 YEAR 1968.

 

  The MAGNADYNE MOD. CR93 is a 19 inches B/W television  and a fumè front heavy dark glass.

Backside VHF and UHF 300 ohm antenna inputs and usual controls for frame /  line amplitude and frequency.

• Tuning is with 2 programs selection with VHF and UHF channels selectors and manual tone controls and classic brightness / contrast / volume.

These sets were cheap and branded even with other names:ETERPHON KENNEDY RAYMOND VISIOLA and DAMAITER.

• the set is almost completely tubes based.

•   Was first model series with a UHF tuner  transistorized.

The tellye here in collection is a ELCIT branded .MAGNADYNE.

In Brief ...........   SEIMART / ELCIT and its conglomerate was even proprietary of brands like:

ETERPHON KENNEDY RAYMOND VISIOLA and DAMAITER.

and

MAGNADYNE + KENNEDY

Founded in 1922 in Torino ELCIT was a Radio fabrication industry which in the 1953 joined Visiola to produce television sets and other domestic appliances such washing machines and fridge.

ELCIT Was even proprietary of the MAGNADYNE brand which WAS a radio and Television well known brand.

In the 1960 the society was joined and aquired by SEIMART because of a market contraction which landed to GEPI a new society which re - founded ELCIT.

The conglomerate of ELCIT AND SEIMART which was a joint developed by GEPI a government special system invented to "save" industry with "some" difficulties (!!!) was unified.


and;

The following sub brands were even from the group but were specialized in other fields like
preparing materials, developing parts and other jobs like domestic appliances and even CRT TUBE manufacutring.

NEOHM was a resistor fabricant and was part of the group

Basically the industry group was completely autonomous exept for semiconductors which were coming from other well known brands and manufacturers.

RADSET

VISSET

NEOHM was a resistor fabricant and was part of the group conglomerate and components factory.

VITAUT (SCREW AND PARTS)
STAMPLAST
STAMFER

BOBSET
CIRSTA
FRIMAX

MOBFER P (METAL PARTS)

TRAMAX
FINPLAST (PLASTIC)
VALVEX (CRT TUBES)

ELCIT died in 1998 by typically Italian Industry Destroy culture and all workers and employee landed.......... on the street !!!!!!!!!!!!!

The Magnadyne Radio, known simply as Magnadyne, was an Italian manufacturer of consumer electronics, electronic components and household appliances in Turin, controlled by the financial holding INFIN S.a.s., active from 1928 to 1955, among the largest in its field at the national level. Ceased to exist as a company, it became a simple commercial brand, which after the bankruptcy of INFIN in 1972, passed under other properties.

The company Magnadyne Radio was founded in 1928 in Turin on the initiative of Mr. Mario Pesce with Mr. Paolo Dequarti as a silent partner, from the change of name of Accumulatori Ohm, owned by the same Pesce. The object of the new company was the construction of radios, electric accumulators and refrigerators.
Its registered office was located in Via Sant'Ambrogio 8, in the Turin district of Pozzo Strada, in the building owned by Pesce, and next to it, at number 10, stood the shed where its activities were carried out, owned by Candido Viberti.
At the time of its establishment, the number of workers employed was of 20 units.

The development of the company was rapid and its products exceeded in sales on the Italian market, larger companies such as CGE, FIMI-Phonola, Philips and Radiomarelli.

In 1931, Magnadyne took part for the first time in an exhibition, the III National Exhibition of Radio in Milan, where was presented the four-valve radio M10.

Three years later, in 1934, at the VI edition of the same exhibition, Magnadyne took part in the exhibition of radio receivers of popular type, organized by the Ente Radio Rurale and the National Research Council, sponsored by the Ministry of Communications, and presented three, four and five valves radio receivers, and four and five valves radiophonographs.
 The number of employees employed by the Turin company reached 300 units in 1936, and grew further the following year, in 1937, when Dequarti took over the S.A. ing. Clemente Diena & C., a company producing telegraphic equipment that employed 61 people and was located in Via Avellino 6, in the San Donato area, whose name was changed to Magnadyne S.A..

The equipment was entirely produced by the Turin company, both in their internal electronic part - except for the thermionic valves supplied by third parties - and in the external part, i.e. the ebony casing.
 The production criteria were modern, based on the industrial production of large-scale series.
 Magnadyne, on the eve of World War II employed over 1,000 workers, and to the production of radio receivers and electronic components were added those of car radios and refrigerators.
 The first car radio model produced by Magnadyne, four valves, in 1937 won a competition organized by RACI.
 
 At the end of the conflict, production, albeit to a limited extent, could be resumed, with the production of components for radio receivers. In 1948, faced with a revival of sales in the radio equipment sector, a new factory was opened in Turin, Via Avellino 6, entirely dedicated to the production of electronic components, where the company's registered office was also transferred.
Four years later, in 1952, the company also started the internal production of thermionic valves.

• In 1955, Magnadyne Radio ceased to exist as a company, and consequently brand and activities were merged into the holding INFIN S.a.s. di Dequarti & C., established two years earlier in Freiburg.
•  This company, which became known as INFIN-magnadyne, its activities were diversified with the production of televisions, cathode ray tubes and washing machines, and since 1961, of transistors.
•  The equipment produced by INFIN-Magnadyne were also marketed under other brands, such as Belvis, Damaiter, Eterphon, Nova, Radioson, Raymond and Visiola.
• In 1964, the INFIN-Magnadyne Group had about 5,000 employees - half of which were employed in the plant in Sant'Antonino and the rest in the three factories in Turin and in the commercial offices scattered throughout the Italian territory - and starting from that year, it showed the first signs of crisis, mainly due to the increase in production costs, the decline in exports and the decline in installment sales of equipment.
•  The crisis of the Piedmontese company worsened afterwards: the industrial activities were downsized, as well as the number of employees, reduced to 3,300 in 1970, and it also found itself facing other problems, such as a liquidity crisis, debts for 2 billion lire, suspension of credits, and blocking of material supplies by subcontracting companies.
• In January 1971, Dequarti was solicited by Edoardo Calleri, president of the Piedmont Region, and Carlo Donat-Cattin, minister of labor, to request admission to the receivership procedure for his company (whose factories were occupied by workers), but the interested party, concerned that such a solution could lead to bankruptcy, did not provide any response in this regard, and the following month, in February, the same Piedmontese governor promoted the establishment of SEIMART, in order to take over the management of activities and absorb the workers of INFIN-Magnadyne.

 Shortly afterwards, in March, Dequarti asked for and obtained the admission of INFIN to receivership by the Court of Turin, which appointed Piero Piccatti as judicial commissioner.

 SEIMART rented the four factories of INFIN-Magnadyne in Turin and Sant'Antonino di Susa, took charge of the 2,000 workers who worked there, and at the expiration of the contract, in April 1972, began negotiations with the property to purchase the factories and machinery.

 After three months, in July, the negotiations between Dequarti and SEIMART failed due to the failure to reach agreement on the sale price, for which SEIMART was willing to pay 700 million lire compared to the 3 billion requested by Dequarti.
 The failure to reach an agreement between the parties provoked new unrest from the workers (at risk of dismissal by SEIMART), who occupied the factories, and this situation led the prefect of Turin, Dr. Giuseppe Salerno, to issue a decree ordering the requisition of the INFIN-Magnadyne plants and the resumption of production activities.


In November 1972, the sixth bankruptcy section of the Court of Turin declared INFIN bankrupt, following the judges' rejection of Dequarti's request for a composition with creditors.
 At the origin of the decision was the serious financial instability found during the administration of Dr. Picatti, who summoned the creditors to file for bankruptcy.

 The debt accumulated by INFIN amounted to 11 billion lire.
 Following the bankruptcy of the Dequarti Group, the tangible and intangible assets owned by the subsidiary companies were auctioned off: in November 1975, SEIMART, through its subsidiary Beta-Geri S.p.A., acquired at auction "without auction" the plant in Sant'Antonino di Susa, with its machinery, its 900 employees and the Magnadyne and Kennedy trademarks, for 750 million lire

 One month later, in December, SEIMART together with Magneti Marelli, established a new company, SEIMART Elettronica S.p.A., with registered office in Turin, where the production activities of the two companies were merged, with the brands Magnadyne, Kennedy, LESA, Radiomarelli and West.


SEIMART Elettronica, which shortly afterwards assumed the company name ELCIT Elettronica Civile S.r.l., was the fourth largest Italian manufacturer of consumer electronics and in 1978 produced 26,000 televisions and had a market share of 2.3%.

 The electronics industry in Italy, in the period between the end of the seventies and the beginning of the eighties, was in a serious crisis due to technological delays and aggressive competition from foreign producers, and therefore in 1982 the Ministry of Industry established REL, a financial company created with the aim of rehabilitating companies in the sector: ELCIT, which in that year had achieved a turnover of 33 billion lire and had 630 employees in the Valsusino factory, was excluded from the intervention of REL, since it was controlled by GEPI and was in fact in public hands.
 In addition to television sets under the Magnadyne and Radiomarelli brands, ELCIT also produced computer monitors for Olivetti and other computer companies.

For much of the 1980s, the business performed reasonably well, despite the technological constraints.

• The modest levels of profitability recorded by ELCIT led GEPI to initiate liquidation proceedings in May 1990 for the company and its employees, who were reduced to just 287 units.
•  The following month, in June, the liquidation procedure was suspended by GEPI, following the mediation of the mayor of Sant'Antonino Val di Susa, and the employees were granted a redundancy fund.
•  In May 1991, ELCIT was privatized and sold to Sandretto, a well-known Piedmontese manufacturer of injection molding machines, but at the same time 115 employees were made redundant in accordance with agreements made between GEPI and the buyer.
• The new owners made large investments to relaunch and diversify production, but nevertheless found it too difficult to compete in the market, now characterized by aggressive competition from Asian and Turkish products. Thus, in 1997, 83% of the staff were laid off.
•  In 1998, in the absence of measures to continue the natural course of the activities, the company closed down definitively, laying off the 100 employees who remained in the plant of Sant'Antonino di Susa, which was dismantled in parallel with the disappearance of the Magnadyne brand from the market.

 

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..............................

Further Notes & references : 

S. Sacco - La Magnadyne di Sant'Antonio. La nascita, lo splendore, il declino e le lotte per la difesa dell'occupazione - Graffio, Torino, 2008, ISBN 88-95057-06-6

^ "L'azienda elettronica che produce televisori in crisi per mancanza di commesse Scatta la cassa integrazione alla Elcit Sant'Antonino: interessa 83 dipendenti su cento", Articolo del quotidiano La Stampa del 3 aprile 1997^{[collegamento interrotto]} ^ Dal sito haikellah.com ^ Dal sito haikellah.com

Annuario industriale della provincia di Torino 1936-XIV, Editrice U. S. I. L. A., p. 86.

U. Alunni, La radio in soffitta, Lulù.com, 2014, pp. 311-315.

Le visite del Federale ai lavoratori, in La Stampa, 22 novembre 1940, p. 2.
^ La III Mostra Nazionale della Radio, in L'Antenna, n. 19, Radioamatori Italiani, 15 ottobre 1931, p. 3.
^ Magnadyne M10, su ansaldolorenz.it. URL consultato il 19 aprile 2021.
^ E. Montù, Ciò che è stato realizzato in un anno di fecondo lavoro, in La Stampa, 22 settembre 1934, p. 6.
^ Annuario industriale della provincia di Torino 1936-XIV, Editrice USILA, p. 95.
^ Catalogo Raci 1938 (PDF), su airepiemonte.org. URL consultato il 20 aprile 2021.
^ Fra gli espositori della IX Mostra della Radio di Milano, in L'Antenna, n. 18, 30 settembre 1937, pp. 595-597.

Notiziario industriale, in L'Antenna, n. 19, Radioamatori Italiani, 15 ottobre 1940, pp. 330-331.

Magnadyne. Stabilimento per la produzione delle valvole, in Notizie e informazioni del gruppo Piemonte/Valle d'Aosta, n. 13, AIRE, gennaio-febbraio 2011, pp. 8-11.

Magnadyne Radio, su airepiemonte.altervista.org. URL consultato il 20 aprile 2021.
^ Alla Magnadyne 2000 licenziamenti?, in Stampa Sera, 9 marzo 1964, p. 2.
^ I 4500 dipendenti Magnadyne tornano alle 42 ore settimanali, in La Stampa, 1º settembre 1964, p. 2.
^ E' un momento difficile per Magnadyne e Tobler, in La Stampa, 5 dicembre 1970, p. 5.
^ I 3300 della Magnadyne oggi riprendono il lavoro, in La Stampa, 22 dicembre 1970, p. 5.
^ La Magnadyne deve chiedere l'amministrazione controllata, in La Stampa, 24 gennaio 1971, p. 5.
^ Costituita la società per la "Magnadyne,,, in La Stampa, 23 febbraio 1971, p. 5.

Dichiarata fallita la società proprietaria della Magnadyne, in Stampa Sera, 24 novembre 1972, p. 5.

Alla Magnadyne 2000 in ansia perché non si trova un accordo, in La Stampa, 18 luglio 1972, p. 4.
^ Magnadyne: una schiarita sospesi i licenziamenti, in La Stampa, 17 luglio 1972, p. 5.
^ Il prefetto fa riprendere il lavoro alla Magnadyne, in La Stampa, 22 luglio 1972, p. 4.
^ L'Infin, società proprietaria della Magnadyne dichiarata fallita con passivo di undici miliardi, in La Stampa, 25 novembre 1972, p. 4.
^ La ex Magnadyne passa al gruppo Seimart, in Stampa Sera, 28 novembre 1975, p. 4.
^ Pignoramenti Imi sulla Magnadyne, in Stampa Sera, 25 febbraio 1976, p. 6.
^ È nata la Seimart Elettronica, in La Stampa, 25 dicembre 1975, p. 14.
^ Che cosa rappresenta la nuova Società, in La Stampa, 25 dicembre 1975, p. 14.
^ Anagrafe Operatori - Regione Piemonte, su extranet.regione.piemonte.it. URL consultato il 20 aprile 2021.
^ V. Ravizza, Tv-color: la guerra dei prezzi intacca i bilanci delle imprese, in La Stampa, 30 ottobre 1979, p. 9.

V. Ravizza, E la Elcit si chiede: «Perché noi fuori?», in La Stampa, 19 maggio 1983, p. 14.
^ Elcit chiude e licenzia 287 addetti, in La Stampa-Sezione provincia di Torino, 26 maggio 1990, p. 37.
^ Elcit non licenzia Erber in vendita?, in La Stampa-Sezione provincia di Torino, 9 giugno 1990, p. 43.
^ La Elcit di Sant'Antonino è passata ai Sandretto, in La Stampa-Sezione provincia di Torino, 4 maggio 1991, p. 40.
^ F. Morello, Scatta la cassa integrazione alla Elcit Sant'Antonino, in La Stampa-Sezione provincia di Torino, 3 aprile 1997, p. 37.
^ F. Morello, Sant'Antonino, chiude la Elcit, in La Stampa-Sezione provincia di Torino, 9 gennaio 1998, p. 40.
^ Redazione, Twenty acquisisce il marchio Sèleco, in E-Duesse.it, 22 dicembre 2016. URL consultato il 21 aprile 2021.
^ B. Andolfatto, TORNANO LE TELEVISIONI MAGNADYNE MA ARRIVANO DALLA CINA E DALL’EUROPA DELL'EST, in La Valsusa, 17 marzo 2017. URL consultato il 21 aprile 2021.
^ Redazione, I ped Magnadyne sugli scaffali dei punti vendita, in E-Duesse.it, 2 dicembre 2016. URL consultato il 21 aprile 2021.
^ E. Sesta, TWENTY SPA CAMBIA IN SÈLECO SPA, in E-Duesse.it, 11 maggio 2017. URL consultato il 9 aprile 2021.
^ R. Broch, SÈLECO AL CAPOLINEA, in E-Duesse.it, 27 maggio 2019. URL consultato il 9 aprile 2021 (archiviato dall'url originale il 25 settembre 2020).
^ A. Bacci, Sèleco, scoperto il bluff: addio rilancio Il tribunale ha dichiarato il fallimento, in Messaggero Veneto - Sezione di Pordenone, 17 maggio 2019, p. 21. URL consultato il 9 aprile 2021.
^ M. Lucchese, MAGNADYNE NUOVO “RETRO” SPONSOR DELL’UDINESE, in Sport Economy, 8 luglio 2016. URL consultato il 21 aprile 2021.
^ Magnadyne tifa S.P.A.L., in Distribuzione Moderna, 24 maggio 2017. URL consultato il 21 aprile 2021.

MAGNADYNE MOD. CR93 CHASSIS 1-7001 1537 / 1-7001 1476 INTERNAL VIEW.

 

The chassis is divided by 2 boards.

•  signal board  left side 
•  deflections board + EHT right side.
  
•  Tuning is obtained with rotatable drum selectors for VHF with a PHILIPS Tuner type:312210850082.
• The UHF TUNER  is transistorized type.
  

 

Tuning is obtained with rotatable drum selectors for VHF and variable rotatable capacitor for UHF.
A rotatable drum containing twelve pre-defined channel-specific filters determines the received channel, where the inductors of the input matching, the channel filter and the LO tank circuit are changed. The tuner is divided into two chambers for maximum isolation between the sensitive RF input and the mixer-oscillator-IF section with its much larger signals. Also on the drum there are eventually two separate sub-modules.
It's completely based on tubes technology.
With this concept, which essentially turned the tuner module into a kind of Lego building block construction, many different tuners became possible. Depending upon the country of destination and its associated standard and IF settings, the required filter modules would be selected. Service workshops and tv fabricants could later even add or exchange modules when new channels were introduced, since every inductor module had its individual factory code and could be ordered separately. As a consequence more versions of the tuner were produced, covering at least standards B, B-for-Italy, C. E, F and M.


The principle of the drum tuner. On an axis two times 12 regularly spaced channel-specific filter modules are mounted. In front are twelve channel filter modules for both the channel filter and LO tank circuit tuning. Seven contacts are available, and one module is shown removed. The second row contains 12 modules with five contacts for the input filter circuit. In the tuner module the front section (for mixer-ocillator and channel filter) is separated by a metal shield from the rear RF input and pre-amp section. [Philips Service "Documentatie voor de kanalenkiezers met spoelenwals", 1954]

Examples of the filter modules as used in the drum tuner. Left the 5-contact input filter, right the 7-contact BPF and LO tank filters. In both modules the coils are co-axial for (maximum) mutual coupling.





1970'S TRANSISTORIZED UHF VARIABLE CAPACITOR TUNER  EXAMPLE:

A continuously adjustable UHF tuner has a multi-compartmented housing each of which has a tunable frequency selector. These selectors are essentially identical to one another in respect of dimension and configuration. Each is made up of a multi-turn inductor which, in conjunction with the compartment walls, constitutes an approximately quarter-wave transmission line at the high frequency end of the tuning band and also of an adjustable capacitor for tuning the selector over a band equal in width to the UHF band. The capacitor has both stationary and movable electrodes. The former is an extension of an end turn of the inductor and the latter has a main body portion and another portion which is located at one end of the main body portion and is adjustable transversely relative thereto. The movable electrode has a first extreme position which is one of minimum capacitance and in which the aforesaid other portion of the movable electrode is the predominant tuning adjustment and is used to establish the high frequency end of the tuning range. The other extreme or maximum capacitance position of the movable electrode determines the low frequency end of the tuning range and a control shaft permits displacement of the movable electrode between these two extreme positions to tune the selector over its range.

1. A variable capacitor comprising two cooperating capacitor plates mounted for movement with respect to each other between a first position wherein the capacitance of the capacitor is at a minimum and a second position wherein the capacitance of the capacitor is at a maximum, one of said capacitor plates having a main part and an auxiliary part, only said auxiliary part of said one capacitor plate being opposite the other of said capacitor plates when the capacitor is in said first position thereof, said auxiliary part of said one capacitor plate being adjustable toward and away from said other capacitor plate, thereby to allow the minimum capacitance of the capacitor to be adjusted, said auxiliary part of said one capacitor plate being not opposite said other capacitor plate when the capacitor is in its second position, said capacitor further comprising means for preventing an abrupt change in the capacitance characteristic of the capacitor at the point where said auxiliary part of said one capacitor plate ceases to be opposite said other capacitor plate.

2. A capacitor in accordance with claim 1 in which said other capacitor plate is configured to constitute said means.

3. A capacitor as defined in claim 1 wherein said one capacitor plate is provided with means forming calibrating electrodes and wherein said auxiliary part has a size and configuration different from that of said calibrating electrodes.

4. A capacitor as defined in claim 1, said capacitor being a rotary capacitor and said one capacitor plate being a rotatably mounted capacitor plate.

Description:

This invention relates in general to wave signal tuners and in particular to an improved continuous type tuner for the UHF television band.

Under present allocations there are two rather widely spaced bands in the radio frequency spectrum which are reserved for television broadcasting. The first, a relatively low frequency band, is designated the VHF band and it accommodates twelve channels; five having frequency assignments between 54 and 88 megacycles and seven between 174 and 216 megacycles. The second band is the relatively high frequency UHF band which accommodates seventy television channels at 6 megacycle intervals between 470 and 890 megacycles.

In view of the relatively few (12) channels in the VHF band, either a turret or a switch type tuner, that is, a tuner having a discrete-stop or position for each channel, is feasible. Insofar as UHF is concerned, however, a discrete-stop tuner is obviously impractical because of the number of positions (70) that would be required. While tuning strips tailored to individual UHF channels are available for use in turret type VHF tuners, the total number of UHF and VHF stations that can be accommodated is limited, of course, to the number of strips which may be accommodated on the turret.

In view of the aforementioned mechanical considerations, the prior art has invariably resorted to a continuous type tuner for receivers designed to accommodate the entire UHF band. The frequency determining circuits for such tuners, however, pose special design problems since conventional lumped constant circuit elements, which ordinarily suffice at VHF, do not function properly at UHF. This is due to the fact that the physical dimensions of such components become an appreciable fraction of the wavelength of UHF signals, and particularly is this the case in the upper reaches of the UHF band. This, in turn, dictates recourse to distributed constant elements, such as tunable transmission lines, for use in the frequency determining circuits.

A conventional tuned-line UHF tuner of the type above-mentioned comprises one or more RF preselector stages, a vacuum tube oscillator stage and a mixer circuit which develops an IF or difference frequency signal by heterodyning a selected RF signal with the oscillator signal. It is conventional practice to use substantially identical quarter-wave transmission line elements, which are tuned by rotatably supported capacitor electrodes, in each of the preselector stages while employing a tunable half-wave line in the oscillator stage. While the operating frequency of the oscillator throughout most of its range is primarily controlled by the tuning capacitor, it is also conventional prior art practice to employ separate trimmer capacitors to insure that the upper and lower limits of the UHF range can be readily tuned. Specifically, when the tuning capacitor is positioned for minimum capacitance, one trimmer capacitor is adjusted to tune the oscillator to the high frequency end of the band. On the other hand, when the tuning capacitor is positioned for maximum capacitance, a second trimmer capacitor is adjusted so as to establish the lower frequency limit of the oscillator. In like fashion, the upper tuning range of the preselector stages is determined by a separate trimmer capacitor in each stage. All of these expedients, while effective, are undesirably costly and complex, both as to component requirements and assembly and alignment procedures in production.

It is therefore a principal object of the invention to provide a new and improved multi-stage UHF television tuner.

It is also an object of the invention to provide a UHF tuner construction which requires a minimum number of component parts.

It is another object of the invention to provide a continuous UHF television tuner of a unique and economical construction.

A continuously adjustable UHF tuner constructed in accordance with the invention comprises a housing which has a plurality of compartments each of which includes a signal translating stage. A control shaft extends through each of the compartments and is rotatably supported by the end walls of the housing. The tuner also includes a corresponding plurality of tunable frequency selector circuits, one for each stage and each comprising an inductor having an electrical length which approaches one quarter of a wavelength at the high frequency end of the UHF band. Each tunable circuit further includes a capacitor having a stationary electrode constituted by an extension of the inductor and an assigned pair of spaced electrodes which are affixed to the control shaft for rotational displacement from a position overlapping and embracing the stationary electrode to a position remote therefrom. All of the displaceable electrodes have a substantially identical configuration and at least one of each of the displaceable electrode pairs has an adjustable tab for establishing, in conjunction with its assigned stationary electrode, the principal tuning capacitance for its associated frequency selector circuits at the high frequency end of the UHF band.

The features of this invention which are believed to be novel are set forth with particularity in the appended claims. The invention, together with further objects and advantages thereof, may best be understood, however, by reference to the following description taken in conjunction with the accompanying drawings, in the several figures of which like reference numerals identify like elements, and in which:

FIG. 1 is an elevation view, in section, of a continuous type UHF television tuner embodying the invention;

FIG. 2 is a sectional view of the tuner taken along lines 2--2 of FIG. 1;

FIG. 3 is a detail view, partly in cross section, of one component of the UHF tuner shown in FIG. 1; and

FIG. 4 is a schematic diagram of the UHF tuner.

Referring now specifically to FIGS. 1 and 2, the continuously adjustable UHF tuner 10 shown therein comprises a metal housing 11 which encloses a plurality of signal translating stages. More particularly, tuner 10 includes first and second RF preselector stages 12, 13, respectively, separated by a compartment wall 14, and an oscillator stage 15 shielded from preselector 13 by a wall 16. A control shaft 17 extends through the compartments and is rotatably journaled upon bearings supported by the end walls 18, 19 of the housing. Shaft 17 is conductively connected to end walls 18, 19 and to compartment walls 14, 16 by a series of grounding leaves 20 each of which has one end soldered to a housing or compartment wall and an intermediate portion seated within an under cut portion of shaft 17, see FIG. 2.

Preselector stage 12 includes a tunable frequency selector circuit comprising an inductor 22 having an electrical length which approaches one quarter of a wave length at the high frequency end of the UHF band. One end of inductor 22 is conductively secured to the top wall 23 of housing 11 while the other end terminates in a planar extension 24 which is supported by a post 21 of insulating material, see FIG. 2. In this fashion inductor 22 constitutes the inner conductor of a coaxial transmission line while the housing and bordering walls form the outer conductor.

Extension 24 serves as the stationary electrode of a tuning capacitor which also includes a pair of spaced electrodes 26 which are soldered, staked or otherwise conductively affixed to control shaft 17 for rotational displacement in a plane parallel to stationary electrode 24 from a position overlapping and embracing the stationary electrode to a position remote therefrom. The latter position is illustrated in FIG. 2. Electrodes 26 are of identical arcuate configuration and each includes an adjustable tab 26', preferably struck or formed along one edge of the electrode itself. As will be explained more completely below, tabs 26' together with electrode 24 serve to establish the principal tuning capacitance for preselector 12 at the high frequency end of the UHF band. Additionally, each of electrodes 26 has a plurality of canted knifing slots 27 to facilitate tuning preselector 12 so that it will "track" or follow oscillator stage 15 when the latter is tuned across the UHF band.

Preselector 12 also includes an antenna input circuit comprising a pair of UHF antenna terminals 28 which are mounted on a panel 25 of insulating material atop housing 11 and are coupled to inductor 22 via a coil 29. One of terminals 28 is returned to a plane of reference potential, housing 11, through a resistor 30 which provides a leakage path for any static charge accumulating on the antenna.

The tunable frequency selector circuit for preselector 13 comprises an inductor 32 which is similar in length and configuration to inductor 22 and is coupled thereto through a window 33 in compartment wall 14. Inductor 32 also has one end grounded to top wall 23 of the housing and a free end formed into a planar extension 34 which is supported by a post 21 thus permitting inductor 32 to serve as the inner conductor of a coaxial transmission line of which compartment walls 14, 16 and housing 11 constitute the outer conductor. Extension 34 is of the same size and configuration as extension 24 and is in alignment therewith as viewed along shaft 17.

Preselector line 32 is tuned by a capacitor which includes inductor extension 34 as a stationary electrode and a pair of adjustable electrodes 36 which are conductively affixed to shaft 17 in axial alignment with electrodes 26 and displaceable over the same limits as electrodes 26. Electrodes 36 are identical in configuration to electrodes 26 even to the extent of having similar slots 27 and adjustable tabs 36' which, together with stationary electrode 34, constitute the principal tuning capacitance for preselector 13 at the high end of the UHF band.

Preselector compartment 13 further includes a mixer diode 35 having one lead connected to a tap on inductor 32 and a second lead protruding through an aperture 37 in compartment wall 16 to form a coupling loop 38 which is connected to the center lead of a feed-through capacitor 39 mounted in wall 16. An IF output coil 40 is connected between the center lead of feed-through capacitor 39 and the center terminal of an IF output jack 41. Jack 41 is coupled to a television receiver, now shown, via a coaxial cable 59.

As is apparent in FIG. 1, capacitor electrodes 26, 36 are mounted symmetrically relative to the walls of their respective compartments. This, of course, permits a measure of control over stray capacitances by equalizing the effects of the strays between the capacitor electrodes and the compartment.

On the other hand, inductors 22, 32 are not symmetrically disposed relative to their compartments in that their center sections are offset relative to their respective extensions 24,34. Although the inductors are substantially identical in length, inductor 32 constitutes, in effect, a mirror image of inductor 22 rather than being identical in configuration. In this fashion their electrode extensions 24, 34 remain centered in their respective compartments while the inductor portions assume positions which provide a desired magnitude of mutual coupling commensurate with the smallest feasible opening for window 33.

Oscillator stage 15 also includes a tunable frequency selector circuit comprising an inductor 42 having an electrical length approaching a quarter wave length at the high frequency end of the UHF band. The low impedance end of inductor 42 is coupled to wall 23 of the housing through a capacitor 43 while its opposite end is formed into a planar extension 44 which is supported by a post 21 and disposed in alignment with preselector extensions 24, 34. Inductor 42 together with housing 11 and walls 16, 19 form a third capacity-tuned co-axial transmission line. Except for the fact that its low impedance extremity is turned back to accommodate a connection to capacitor 43, see FIG. 1, inductor 42 is substantially identical in length and configuration to inductor 32. The tuning capacitor for the oscillator stage comprises inductor extension 44 as a stationary electrode and the pair of adjustable electrodes 46 which are conductively secured to shaft 17 in alignment with preselector electrodes 26, 36 for displacement in the same manner as those electrodes. While they do not have the canted knifing slots found in electrodes 26, 36, each of electrodes 46 does have a single tuning slot 47 which is located outside that area of the electrode which confronts stationary electrode 44 and is disposed normal to the straight edge of the electrode, see FIG. 3. In other respects, electrodes 46 are identical in configuration to preselector electrodes 26, 36 and, in like fashion, include adjustable tab portions 46' which cooperate with stationary electrode 44 to establish the tuning capacitance for the oscillator at the high frequency end of the UHF band.

As previously noted each of preselector stages 12, 13 and oscillator 15 also employ substantially identical inductors 22, 32 and 42, respectively. Therefore, insofar as the major components are concerned, the three stages are identical. It is appreciated, of course, that oscillator stage 15 must operate at a frequency which is displaced 40 megacycles from and preferably above, the operating frequency of the preselector stages. The oscillator stage maintains this frequency separation by virtue of capacitor 43 which is disposed in series relation with tuning capacitor 46, 46' thereby reducing the total capacitance of the oscillator stage and permitting tuning to a higher frequency.

The low impedance end of inductor 42 is directly connected to the output electrode or collector 49 of a grounded-base NPN transistor oscillator 50. By employing a low impedance oscillating device such as a transistor, a quarter-wave line or inductor is feasible. Collector 49 is connected to a source of unidirectional potential B+ via a decoupling choke 51, a feed-through capacitor 52 which is mounted in the top wall of housing 11, and a voltage dropping resistor 58. The emitter electrode 53 of transistor 50 is returned to reference potential housing 11, through a current-limiting bias resistor 54 which also serves to isolate the emitter from RF energy. The base or control electrode 55 is connected to B+ potential through a feed-through capacitor 56, a resistor 57 and resistor 58.

It is recognized, of course, that a PNP transistor can be substituted for transistor 50 simply by reversing the return connections of choke coil 51 and bias resistor 54. More particularly, such a substitution would merely entail returning collector choke 51 to reference potential and then connecting emitter resistor 54 through feed-through capacitor 52 to B+.

Located within the oscillator compartment is a range or limit control comprising a post 60 anchored to compartment wall 16 and a stop 61 which is affixed to shaft 17 and includes a pair of abutments 62, 63 which cooperate with post 60 to confine the rotation of shaft 17 to an angular displacement of approximately 200°, the travel required by capacitor electrodes 26, 36, 46 to tune their associated inductors across the UHF band.

UHF tuner 10 is actuated by a viewer control knob which is coupled to shaft 17 through a conventional gear reduction and vernier mechanism, now shown. Initially, however, tuner 10 must be set-up or phased by a test procedure which establishes the correct tuning range for each of the several stages. An acceptable procedure entails energizing transistor 50 and then rotating shaft 17 counterclockwise, as viewed in FIG. 2, until abutment 62 of the limit control encounters post 60. Transistor 50 functions as a conventional grounded-base oscillator and develops an output signal across frequency determining circuit 42, 44, 46. RF oscillator energy is coupled from this circuit to mixer diode 35 through loop 38. With shaft 17 so positioned, oscillator inductor 42 is tuned, principally by adjusting the proximity of electrode tabs 46' to electrode 44, to a frequency near the high end of the UHF band.

The frequency range of the oscillator is then adjusted by coupling the output of a sweeping generator to antenna terminals 28. In addition to an UHF signal varying in frequency above and below UHF channel 83, the output of the sweeping generator also includes a marker pulse which identifies the video carrier for channel 83. This sweeping signal is coupled to inductor 22 of preselector 12 through coil 29 and from there to inductor 32 of preselector 13 through coupling window 33. A portion of this signal is also injected into mixer diode 35 by virtue of the tap on inductor 32. To the output of diode 35 is externally added a pair of markers which are separated by 41/2 megacycles and represent video and sound IF carriers. This composite signal is then externally detected and applied to the terminals of an oscilloscope. The displayed pattern shows the channel 83 marker, as well as the sound and video IF carriers, and also gives an indication of the pass band of preselector stages 12 and 13. The frequency of oscillator 15 is adjusted for the high end of the UHF band by positioning electrode tabs 46' relative to electrode 44 until the channel 83 marker on the scope pattern is properly disposed in relation to the sound and video IF markers. The pass bands of preselectors 12, 13 are then adjusted by positioning their respective electrode tabs 26', 36' relative to electrodes 24, 34 until a desired pass band is displayed on the scope.

The oscillator is next adjusted for the low end of the band by rotating tuning shaft 17 until stop abutment 63 engages post 60. The previously described procedure is then repeated using a sweep signal centered about UHF channel 14. The oscillator frequency is now adjusted by inserting a tuning wand in slots 47 of electrodes 46 and positioning those electrodes relative to electrode 44 until the scope pattern reveals proper oscillator frequency at the low end of the band.

Tracking of the oscillator across the UHF band by the preselector stages is then checked by returning tuning shaft 17 to the channel 83 position. Tracking is accomplished by successively positioning control shaft 17 to tune in a series of stations in the UHF band. More particularly, shaft 17 is rotated clockwise, as viewed in FIG. 2, to a position corresponding to UHF channel 75, for example, at which station a sweep signal having a frequency centered about that channel is coupled to antenna terminals 28. Preselector stages 12, 13 are then "tracked" to the oscillator by inserting a tuning wand alternately in the slots 27 of capacitor electrodes 26, 36 and bending the section of the electrode adjacent the slot, i.e., "knifing" the rotor elements, until a pattern of desired band pass is displayed on the oscilloscope. Control shaft 17 is then rotated to another position where the above procedure is repeated a second time. The knifing procedure is repeated for as many channels as is required to achieve proper tracking of the preselector circuits.

As shown prior art trimmer type capacitors are eliminated by resort to the disclosed electrode-tab arrangement in the frequency determining circuits of the several stages. Moreover, a substantial economy is achieved by forming electrodes 26, 36 and 46 from the same tool. This procedure also eliminates any tuning discrepancies attributable to differences in electrode size or configuration. Moreover, by forming these electrodes from the same tool any change in electrode size or configuration due to tool wear will not affect one stage any differently than any other since all the electrodes will retain an identical shape and configuration.

In another aspect, section 12, for example, of the UHF tuner of the present invention comprises a variable capacitor including cooperating rotor and stator capacitor plates 26 and 24 respectively, the rotor plates 26 being mounted for rotary movement with respect to stator plate 24 between a first position wherein the capacitance of the capacitor is at a minimum and a second position wherein the capacitance of the capacitor is at a maximum. Each of the rotor plates 26 has a main part and an auxiliary part 26', and only the auxiliary part of the rotor plate 26 is opposite the stator plate 24 when the capacitor is in its minimum capacity position. Auxiliary parts 26' of rotor plate 26 is adjustable toward and away from the stator plate 24, thereby to allow the minimum capacitance of the capacitor to be adjusted. Auxiliary part 26' of rotor plate 26 is not opposite stator plate 24 when the capacitor is in its maximum capacity position. The variable capacitor further comprises means for preventing an abrupt change in the capacitance characteristic of the capacitor at the point where auxiliary part 26' of rotor plate 26 ceases to be opposite stator plate 24, such means constituting the bottom tapered edge of stator plate 24 which is non-parallel or forms an angle with the edge of auxiliary part 26' of rotor plate 26 as the rotor is turned clockwise to the point that auxiliary part 26' departs from confronting relationship with stator plate 24. It will be observed that rotor plates 26 are provided with means in the form of slots 27 to form calibrating electrodes, and that auxiliary part 26' has a size and configuration different from that of any of the individual calibrating electrodes.

By the same token resort to a low impedance device for the oscillator stage, transistor 50, permits use of substantially identical tuned quarter-wave lines, inductors 22, 32, 42, in each frequency selector circuit. The savings which accrue as a result of employing substantially identical components in each of the three stages of the tuner contribute not only to economy in component cost but also a reduction in labor cost because of the resultant simplicity in manufacturing the tuner.

While a particular embodiment of the present invention has been shown and described, it is apparent that changes and modifications may be made therein without departing from the invention in its broader aspects. The aim of the appended claims, therefore, is to cover all such changes and modifications as fall within the true spirit and scope of the invention. 

 

• Inventors:REYNOLDS WAYNE H 
• Assignee:ZENITH RADIO CORP. 

MAGNADYNE MOD. CR93 CHASSIS 1-7001 1537 / 1-7001 1476 CRT TUBE NEOVIDEO 19BV3/S.

 

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..............................