Recollections of BBC engineering from 1922 to 1997
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My early days at TV Centre
by Dick McCarthy

I joined the BBC as an engineer in 1967, and after a few months in the Studio Unit of SPID (Studio Planning and Installation Department), based at Henry Wood House, transferred to Television Network department at TV Centre, where I stayed for the next 33 years. I would like to share some of my experiences of those early years with people, so that they can get some idea of television operations in the late sixties and early seventies. It is not intended to go into great technical detail, more to describe the different areas that I worked in in my early years. Everything is based upon my personal experiences, and what I can remember, and so if anything is left out, it is probably because I didn't have a personal involvement.

I first became involved with TV Centre on my second day in the BBC, in June 1967, as an engineer in SPID. I found myself in CAR (Central Apparatus Room), working under the late Eric Taylor, having to equalise and time the vision feeds for the new colour production studios TC6 & TC8. I suppose because I had spent the previous 4 years working for Rediffusion Engineering, in between going to college, I was deemed to be fully capable of doing the job; and this was before going to Wood Norton! These were exciting times. Colour television was starting on BBC2, and I well remember getting distracted by watching the 1967 Wimbledon Tennis Outside Broadcast on one of the Rank Bush Murphy colour monitors in CAR. I visited TC6, 7, & 8 CVAR (Combined Vision Apparatus Room), several times, to carry out equalisation on the OS and output lines, using a pulse and bar test signal, and a variable equaliser test set called a ’Fairy Fingers’. I then had to work out the values of the components to construct fixed equalisers, and get a wireman to build them, including winding the inductor coils. The CVAR was designed for both 525 and 625 line working, as at the time of planning these studios, there was no equipment available to carry out colour field store standards conversion, so it was felt that the best solution, with an eye on selling programmes to the States, was to have the means of originating in 525 NTSC, if required. Thus the CVAR contained both PAL and NTSC coders and decoders, with EMI 2001 and Marconi MkVII cameras being able to work on 525, as well as 625 lines. I do remember one programme originating from TC6 (or was it TC8) in 525 NTSC, and that was the comedy, 'Charley’s Aunt'. This must have been sometime in 1969, when the Advanced Field Store Colour Converter, RD1, was available to convert from 525 NTSC to 625 PAL. Since 'Charley’s Aunt' was made to be shown both here and in the USA, in colour, and no suitable converter existed to convert from 625 to 525, it had to be made in 525, and converted via RD 1 for the home audience.

Another job I was given to do in CAR, was to replace all the valve amplifiers in the studio vision outputs by new BBC transistorised ones, to improve the performance of signals in the vision chain. After a couple of other projects involving sending vision signals to Kensington House, via Union House, on twisted audio pairs, using a balanced sending arrangement to reduce crosstalk, and refurbishing the VIP Viewing System, which enabled me to visit all the posh offices in the 6th floor Direction Suite of TV Centre, I decided to transfer to Television Network and get involved in television operations. To be honest, the true reason for the move was to work shift, as I noticed the people on shift seemed to have every other day off. I started off in Television Network in Presentation Studio A in early '68. The studio had three EMI 201 vidicon cameras, with a valve vision mixer, and was working on 405 lines. NC1 (Network Control Room 1) next door, also had valve vision mixing equipment, and was also working on 405 lines. I became immersed in the joys of ‘racking’ the cameras, for Promotions and Weather, with the occasional ’Points of View’ presented by Robert Robinson. In those days the Weather presenters only numbered 4, and were Bert Foord, Graham Parker, George Luce, and Peter Walker. There were two permanent weather charts in ’A’; one Atlantic, and one British Isles, with magnetic isobar strips, which the weatherman had to stick on the charts before the transmission or recording. It is taken for granted now that VT insert machines run sync, but in those days sync working by Ampex VR1000 machines depended on devices like Intersync and Amtec, and couldn’t be guaranteed. Several times, just before a live trail, the Promotion Director had to be told that the insert VT machine couldn’t run sync. This obviously ruined the TX, as no studio captions could be superimposed over the VT replay.

Presentation studio B, next door, was working on 625 lines, and in colour, with a mixture of 3 makes of colour camera. They were field testing the relative merits of 3 and 4 tube cameras, to decide which colour cameras should be used in the main production studios. The camera control units for Pres B were housed in the NC2 Apparatus Room, which itself had its own claim to fame. It was where the first video tape machines i.e. Ampex VR 1000' s, were installed in TC before the VT area was established in the Basement. The main output of' ‘B’ in those days was 'Late Night Line Up' or LNLU for short, and this provided the early grounding in colour working for many Network engineers, being the first studio in TV Centre to regularly produce programmes in colour, until September 1967 when TC6 opened. I wasn’t allowed to work in Pres B at this time, as I hadn’t yet been on the ETD colour course (that came later in 1968). At the end of the 4th floor corridor, by the main doors, a room was being constructed to become the CVAR for both Pres A and B, as up to then the vision equipment was split between NC1 and NC2 Apparatus Rooms. Previously, this room had housed a colour caption scanner for BBC2 use, and a temporary home was found for it in CAR .

In March 1968, the decision was made to put NC I and Pres A on 625 pulses, even though the BBC1 service was still only 405 lines from TV Centre. The reason for this was to ease the Network 1 operation, since a large number of programmes were now only available on 625, including the News up at Alexandra Palace, and any BBC1 programme originating on 625 lines had to be first converted to 405 lines in the Standards Conversion Area, before being handled by NC1 (when it was still working 405). This meant the staff in Standards Conversion having to 'shadow' the NC1 operation. From the date when NC1 worked 625 lines, any incoming programme on 405 lines, mainly Regional material, had to be taken in emergency cut to bypass the NC1 vision mixer. On the output of NC1 were two Line Store Standards Converters, SCV11 and 12, (main and reserve), which converted in the direction 625 to 405. If 6251ine signals were present on NC1's output, the Converter output was fed to Network 1 distribution. If 405 line signals were present on NC1’s output, the Converter was bypassed. This arrangement avoided the need for double conversion when handling 405 line signals, apart from the fact there was only one 405 to 625 Line Store Converter. An auto line standard sensing device decided if the NC1 output should be converted or not. I remember at least two occasions when this device malfunctioned, and decided to feed a 405 line signal via the Converter to line. BBC 1 viewers were treated to what can only be described as an early form of scrambling! This hybrid system lasted until November 1969 when the BBC 1 service went 625, (and colour), and line store conversion then took place at the transmitting stations to provide the 405 service to the VHF transmitters.

About June 1968, I was posted to CAR, where I had worked previously as an SPID engineer. The CAR desk was manned (per shift)by two grade C, and two grade D engineers, with two grade B1 Supervisors. The Supervisors shared a small desk at the rear of the main desk, and reminded me of school, with the teacher keeping an eye on his pupils. The bays in the apparatus area run the length of CAR, with vision equipment on one side of the room, and sound equipment on the other side. The sound bays were mostly packed with grey painted valve amplifiers, such as C/9's and GPA's. The Main Routeing audio and comms circuits were switched by Motor Uniselectors, installed late 1950's, and housed in their own room at the back of CAR. These were working up to 1997, when they were removed, and the room used for the new encoding equipment for digital television transmissions. Even some vision signals were switched by mechanical switches at this time. Motorised wafer switches, called Ledex switches, were used to route TK and VT vision signals to the studio OS lines. All other vision routeing was carried out using BBC designed relay matrices. The relay matrix was an improvement on the Ledex switches, and not just in performance, as the latter could only route one source to one destination. The relay matrix did, however, have the drawback of requiring the use of a soldering iron to change the input and output amplifiers, or replace a relay strip; not a simple card change. Test Cards were generated using a mixture of Monoscopes (a type of camera tube with a test pattern etched on the target), and Transparency Scanners. One of the main duties of the CAR vision engineer every morning was to line-up the Test Card Scanners for Test Cards C, D, and F, as they appeared on-air a lot more frequently in those days; in fact a large part of the BBC2 daytime schedule consisted of Test Card F. The News was still at Alexandra Palace then, and before a News studio could go on-air via NC1 or NC2, the source (a vision and sound circuit from AP), had to be selected by CAR staff to the booked BH to TC vision and sound circuit, by remotely controlling a matrix at BH Switching Centre. It wasn’t possible to quickly cut to a News studio, as is done today. At that time CAR had to handle a mixture of 405 lines, and 625 line monochrome and colour signals. There were 405, 525, and 625 line pulse chains, with elaborate techniques for source synchronisation. There were no digital synchronisers then, and the main method of making OB's or Regions sync into a studio was to use a pulse locking system i.e. genlock or slavelock. The alternative was to use an optical standards converter, but more about that later. It should be pointed out that OB's and Regions were normally only picture phased into Network, (to avoid a frame roll during the cut), and were not sync. This was the era of CLNGS (Constant Line Number Generator Synchroniser), often referred to as 'Willie Nobles', after its designer, and these devices compared local and remote sync pulses, modifying a twice line frequency signal to a local SPG, in the case of genlock, or to a remote SPG, in the case of slavelock. Locking could take up to 30 seconds, depending on the picture phase difference between local and remote signals, but could be speeded up by initially picture phasing before locking. Since 405 line signals were mains locked, (to reduce the visibility of hum on some receivers), a piece of equipment called a Goniometer was used to shift the phase of a mains reference into the CLNGS, and hence move the SPG timing relative to other SPG's locked to mains.625 line SPG's were crystal locked, and a variable divider unit was used to achieve picture phasing. The two master chains, 4A for 405, and 6A for 625, were not subject to any timing change. At this time, because of the introduction of colour, a new system of pulse locking had also come into service, known as Natlock, short for National Slavelock, and this became the accepted method of achieving source synchronisation for many years until the digital synchroniser came on the scene around the late 70's. The Natlock system relied upon the use of audio tones to convey error signals for sync timing and colour phase, from CAR back to an OB or Region. A telephone control line (with no Ringers) was required to convey these tones, and during the line-up of each OB or Region, it was necessary to equalise this control circuit to ensure it could carry a range of 7 different tones, each representing a different error signal. The time taken to carry out this equalisation, apart from checking all the other signals from the source, and a wait of up to 4 minutes for full colour lock to be achieved, meant that some OB's were not sync until seconds before being on-air. No instant sychronisation in those days. A refinement of this system, that came later, was Icelock, whereby the error signals were sent as digital signals in the Network signal Vertical Blanking Interval, and Regions and OB's used BBC1 or 2 signals to receive the Natlock errors. It didn’t always work well if the OB had poor BBC1 or 2 reception from their Check Receivers. There was in fact a distance limitation on Natlock, the loop delay had to be less than a certain figure, or else satisfactory lock couldn't be achieved. I think that whenever we slavelocked Aberdeen to London, it was always touch and go.

A few weeks later, I moved upstairs to the Standards Conversion Area where equipment existed for changing the line and field frequency of signals between the four standards in use at that time i.e. 819, 625, 525,and 405 line. There was a mixture of optical and electronic converters, and the whole area was very spacious. There was even an 819 line test generator for checking equipment involved in 819 line conversions, although I think these were rare. The optical converters were no more than a TV camera looking at a high quality monitor, but obviously refined to minimise the various defects that the conversion process introduced, particularly when converting between different field rates. There were three basic types according to the type of camera tube used i.e. CPS Emitron, Image Orthicon, and Vidicon, and all required a great deal of skill to produce acceptable results. I certainly remember converting some 'Forsyte Saga' episodes from 625 to 525, using the Fernseh Vidicon converters, and carrying out 405 to 405, and 625 to 625 synchronisation (an alternative to pulse locking), on the Image Orthicon converters. Because the CPS Emitron and Vidicon converters could handle 525 lines, they could be powered from 60Hz mains obtained from rotary converters. There were also several electronic converters, and most of these were the Line Store Standards Converters, designed by the. BBC, and used mainly to convert from 625 lines to 405 lines. Two of these were permanently tied to NC l' s output, as mentioned earlier, with a third as a spare. The remaining two Line Stores were used for general programme conversion. One for 625 to 405, and one for 405 to 625. Since at this time, most, if not all, the Regions were still working on 405 lines, the daily News feed from Alexandra Palace, on 625 lines, to the Regions, as part of their evening opt-out programme, had to be brought into TC for conversion to 405 lines before being fed out again to wherever it had to go. All the foregoing equipment could only handle monochrome signals. With the start of the colour service, there was a requirement to be able to convert between 525 and 625 in colour.

To enable this, Design's Department built two simple converters, known as DD1 and DD2. These were three bays of equipment each, and converted in one direction only. DD1 did 525 NTSC to 625 PAL, and DD2 did 625 PAL to 525 NTSC. They used ultrasonic quartz delays to store a complete incoming field, (hence they were called Field Store Converters), and an oven was used to keep the quartz delay sections at a precise temperature to ensure the delay remained the same. It was the job of the early engineer in the area to use a resistance box, as part of an impedance bridge, to measure the oven temperature, and adjust for any drift. These two converters, however, had two drawbacks. When converting from 525 to 625, a 525 line picture was fitted into a 625 line raster, and with a corrected aspect ratio, it appeared as a smaller picture bordered like a postage stamp, although nothing was lost. I remember the Continuity Announcer having to apologise for the small picture every time DD1 was used on-air. This converter was used. to convert the early 'Rowan and Martin's Laugh In' programmes that went out in those days on BBC2. Although British viewers never saw the output of DD2, this converter actually lost picture information, as it was fitting part of a 625 line picture into a 525 line raster and with the corrected aspect ratio, appeared like a zoomed in picture. The other problem with these DD Converters was that two PAL or NTSC outputs existed. One with the right colour subcarrier frequency, but not locked to line syncs, and one with the wrong colour sub carrier frequency, but locked to line syncs. The former was referred to as the Transmission output, and the latter, as the Record output. It came about because 525 NTSC field frequency was not 60Hz, but 59.94 Hz. The DD converters used a rigid 5 to 6, or 6 to 5, ratio when converting the field frequency, and this resulted in the subcarrier, line, and field frequencies being 0.1% low, in the 525 to 625 direction, but 0.1% high in the opposite direction. This meant that both Transmission and Record PAL and NTSC decoders existed for monitoring. The Record output was suitable for later transmission, once recorded, as on a VT replay locked to station pulses, the standard frequencies were produced. Having two outputs from DD2 gave rise to problems when feeding the converter to the USA, which was most nights with News material from the three main American broadcasters, ABC, CBS, and NBC, based in London. All the material was on film, but there was only one Telecine machine that could work 525, so most feeds needed to be converted when 625 Telecine machines were used. Initially, the converted feed sent depended on if they were transmitting live or recording, but the problem was solved by feeding the Record output to the States, and getting the US broadcasters, to carry out an NTSC decode/recode to provide a signal suitable for live transmissions. There were also a couple of SECAM to PAL transcoders in the area to handle the occasional SECAM signals from France or Eastern Europe.

All this changed in the latter part of 1968, when Research Department staff arrived to install RD1, the Advanced Field Store Colour Converter. It was 7 bays long, and was installed in place of the CPS Emitron converters. It only converted from 525 to 625, but was a big improvement, as it gave full picture size, a standard PAL output, and was a synchronous source. It's only competitor was a Bosch colour optical converter, using three cameras, and in use by some broadcasters. RD1 spelled the end of DD1, and made its debut in converting the 1968 Mexico Olympics from 525 to 625, in colour, for 28 broadcasting organisations around the world. When the Olympics started, I was busy providing an optical back-up, on the Fernseh converters, just in case RD1 failed, when in walked James Redmond, the then Director of Engineering, asking how things were going! Converter DD2 was still used, however, to provide outgoing feeds to the States, but was replaced about June 1969 by converter RD2. This was very similar to RD1, but converted from 625 to 525, and made its debut in feeding pictures from the Prince of Wales's Investiture at Caernarvon Castle, to a 525 audience. Following this, RD2 was dismantled, and returned to Kingswood Warren for modification to provide additional 625 to 625 synchronisation facilities. It re-appeared in the Standards Conversion Area in early 1970. As a synchroniser, it provided the world's first electronic means of synchronising colour pictures, and was the first ‘instant' synchroniser. The 'Grandstand’ programme made full use of it, and I can recall a particular Saturday when Lime Grove Studio E, the 'Grandstand' studio, was synchronous into Cardiff, simultaneously with Cardiff synchronous into 'E'. This could never have been done before using just pulse locking techniques. A modification was also made to RD2 to enable it to synchronise SECAM signals, prior to being fed to the SECAM to PAL transcoders. This overcame a problem in the transcoders, which like DD1 and DD2, had both a Transmission and Record PAL output, because of the ‘looser’ spec of SECAM signals compared to PAL. Without doubt, my most memorable experience was the night of the moon landing in July 1969. I was on duty in the Standards Conversion Area, and RD1 was being used to convert the incoming 525 pictures to feed many parts of the world. The announcement was made that ‘The Eagle has landed’. All hell broke loose. Everyone in the world wanted to feed to the States with their congratulations, and so RD2, and the two Vidicon opticals, were kept busy converting the incoming 625 pictures to 525. I was still lining up one of the optical converters when the Prime Minister, Harold Wilson, appeared on the screen, live from Downing St. One incident sticks in my mind for this event. It was usual to complete a programme log for all conversions, showing the source and destination. One of my colleagues entered the source as 'The Moon'. Can this ever be beaten?

Looking back over the years, I feel I was fortunate to be around when so many developments in television broadcasting took place.

Dick McCarthy
August 2010