Pye could not deliver a complete Turnkey Television System without the transmitter to broadcast the signal to the home.
After World War II B.J. Edwards appointed Jim Bennett, on the right of the picture below, to lead a team to develop the transmitters to go with the rest of the products such as the studio cameras to build a complete system.
Fortunately the wartime aerial mast was still at St Andrew’s Road so it would come in useful in the future.
1947 - 1948
The first product to be developed was a 25 Watt Band 1 Television Transmitter which was installed to deliver test signals such as Test Card ‘C‘ to the factory for testing television sets.
This type of transmitter was used to transmit pictures from the first demonstrations of television by Pye in Copenhagen and Stockholm.
In March this year, for the first time, pictures were obtained from a launch following the crews in the Oxford and Cambridge boat race. The 25Watt Transmitter was installed on the launch ‘Consuta’ which had a single camera on board.
The Pye engineers were pleased as Cambridge won by a canvas!
The Boat Race in 1949
The first time a television picture was obtained from a launch on the Thames using a Pye Transmitter
In this year a Band III version of the 25 Watt Transmitter was introduced. When used again for the boat race interference from Band I transmissions, which occurred in 1949, were eliminated.
The transmitter, on board a Bristol Freighter aircraft, was used to provide the first air to ground television signals from an aircraft for the BBC.
The first air to ground TV Broadcast
The world’s first 500Watt Band III TV Transmitter was developed.
It was first used to transmit signals from HMS Reclaim which was carrying out underwater television trials looking for wreckage using a special Pye camera.
Pye supplied the first TV Transmitter to be installed on the African Continent at Casablanca. It comprised a 500Watt vision and a 100Watt sound transmitter. It operated on the French 819 line system as the French controlled broadcasting in Morocco.
Two 5kW Band III Transmitters were installed at the ITA Lichfield Transmitting Station to provide ITV broadcasts in the Midlands, one being the main transmitter and the other a passive reserve.
Transmitter Control Console
A system was designed and patented which enabled the two Lichfield 5kW Band III Transmitters to operate in parallel. This enabled a break free transmission should one of the two fail.
This technique was used when UHF transmitters were introduced in 1969 for Colour TV and thereafter.
The two 5kW Transmitters
A 1kW UHF Transmitter was designed using a three cavity klystron as its power amplifier.
Approximately 50 were supplied to the Supreme Headquarters of the Allied Powers Europe (SHAPE).
They were used for a tropospheric forward scatter communications system called ACE HIGH.
“One night in the Spring of 1961 disaster struck”.
These were the words of Jim Bennett when he got a phone call to report that the Tower Hut (where transmitters were built) was on fire.
Six SHAPE amplifiers and two 5kW Transmitters destined for Mt Kippure were destroyed.
In spite of this, in double quick time, the two Dublin transmitters were rebuilt.
As a result of experience gained in the application of klystron power supplies Pye received an order to supply 25kW UHF TV Transmitters to the BBC.
The first parallel operating pair were installed at the BBC’s station at Wenvoe in 1963.
Jim Bennett explaining the working of the transmitter to BBC engineers
In this year Princess Margaret visited the factory which had now moved to York Street alongside Pye Unicam.
With Jim Bennett is Princess Margaret and The Hon. Roger Frankland of Pye.
This 10kW UHF transmitter was produced earlier in the year for the Swiss PTT. Many of these transmitters were produced for overseas customers and also the BBC and ITA (Independent Television Authority).
Later in the year 25kW UHF Transmitters were supplied to the ITA for the opening of their colour television service. Two of these transmitters were installed at each station and operated in parallel.
In this year a 12.5kW Band III Transmitter was produced, a number of which were supplied to the United States.
In the top of the left hand cabinet is the sound power amplifier and the vision penultimate amplifier with panel opened.
In the lower part of this cabinet is the IF modulator.
The right hand cabinet houses the vision final power amplifier below which is the high voltage power supply.
A 55kW UHF Transmitter was developed and produced in two versions either employing internal or external cavity klystrons.
These types of transmitters were sold to Canada and the USA, the flagship being The World Trade Centre installation where two 55kW transmitters were operated in parallel to produce 110kW.
First produced in 1980 this 15/25kW Transmitter was supplied to the IBA (previously the ITA) to establish the new Channel 4 network.
They employed the more efficient external cavity klystrons produced by the Philips owned Valvo company in Hamburg.
Although the main products were television transmitters, TVT moved into radio transmitters with the introduction of a 10kW MF Transmitter some of which were sold to the BBC. However the move to solid state technology soon rendered the design obsolete.
Another product was a solid state 500Watt Band II Radio Transmitter.
500W Solid State TX
10kW MF Radio TX
Television Transmitters at Pye TVT
1980s - the end of TVT Transmitters
In this period the Sceptre Solid State Television Transmitter was developed and a large contract was obtained from Indonesia.
However Philips, having pulled out of the TVT Studio business in 1986, decided to sell the remaining transmitter arm to Varian in 1988 which retained the title TVT.
New power devices were introduced such as the klystrode but in 1990 Varian sold the business to Harris where the company continued to work at the Coldham's Lane factory before it was closed in 2002 and moved to Huntingdon.