Recollections of BBC engineering from 1922 to 1997
The British Broadcasting Corporation
web site is: www.bbc.co.uk
Information Exchange and Contact
|This page is intended to help people who are seeking or offering assistance with matters relating to BBC engineering.||To contact the originator of an item below, click the link in the relevant section. I will forward your email to the intended recipient.||Let me know if you would like an entry on the page.
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White pulses in the active picture area
Chris Clift is seeking help to identify white pulses during the
vertical blanking period (or possibly right at the start of the active
picture area). Click here
to see an image* which illustrates the pulses annotated in the red
box. He writes: "No they are not interval cue-pulses or station idents
(Digital On-screen Graphics). I am a forensic investigator with a
broadcast engineering background and despite researching into this
issue I am stumped. Can you help? As you can see from the image, the
pulses are in the top left hand corner of the active picture area or
possibly just above in the blanking period. I suspect they are just
into the active picture area, but unfortunately the waveform monitor I
have access to does not allow me to expand down to line level to
confirm. These pulses only occur on imagery that has either been
captured digitally or possibly subsequently imported into a digital
editing system. I have seen such pulses on everything from domestic
digital video cameras through to ENG broadcast output. My questions
1. What are these pulses and what do they signify?
2. Does different equipment or do manufacturers generate a different set of pulses? (I have been asked to investigate one piece of video which has, due probably to a copy/encoding error, two different sets of these pulses, the 1st being positioned in the correct place, the 2nd in a blanking period that appeared ¾ of the way into the active picture area, due to the corruption. The pulse sets are different from each other!!!)"
*Please note, the composite image attached is a sanitised version of an actual image and as such contains no imagery, only a grey raster. The horizontal dimensions are accurate but the vertical dimensions may not be completely accurate (if you end up measuring them). The image is for illustrative purposes only, but clearly represents the area to be identified.
Resolved by Glyn Morgan and Martin Brown.
From Glyn: I believe these to be Wide Screen Signalling, WSS. Now we are all digital these should not really leak out for broadcast but often do, especially in news reports. WSS is on just over the first half on line 23. In analogue the active picture did not start until latter half of line 23 but for digital signals all of line 23 is in the active picture. WSS is specified in EN 300 294 which can be found here, or in long form here.
From Martin: What you are seeing is the widescreen
signalling pulses, which have inadvertently been displaced .....
|8-Apr-13||Calrec Minimixers||Matt Oliver writes: "Are there any BBC engineers that may remember using Calrec Minimixers? (MK1 versions.) If so, I'd be interested in hearing them share their experiences with these. Mine is Serial no 077. I'm also looking for a schematic for the DB1491 Compressor/Limiter module. (Click on the pictures to enlarge them.)|
|21-Feb-13||Calrec console||Brian Moran writes: "I would like to expand a BBC Calrec J-series console I have in my possession. I would be interested in any complete consoles or any parts (PQ10,/PQ14/PQ15S, RL23'S or any console frame/sidecars etc), in any condition. Thanks."|
|8-Feb-13||RP2/7 disc reproduction||Marnix Bosman has just acquired a couple of RP2/7 disc reproduction cards and would be very interested to know something more about them such as schematics and/or pin-outs.|
|29-Nov-12||HD recording: "Prince of the Pagodas"||
Ron Isted writes: "First of all, though I spent several years as a
vision mixer before becoming a tel. producer/director, I am NOT an
engineer, so please excuse any technical errors in the next paragraph!
About 1990 I remember directing a performance from Covent Garden of the above ballet, using experimental HD equipment developed (I think) by BBC Research Dept Kingswood Warren. I am sure I was told they operated on a 1250 line system (ie twice 625) and were therefore more compatible with the then current system. Any information about the type and number of cameras available, also recording details (I believe it used four digital machines, but I may be wrong about that). Finally does anybody know if the recording is likely to be still in existence, as I believe some of RD's archive has been transferred to modern formats? Thanks for any help"
|Huw Williams writes: "I have 2 of AM6/7 & 2 Pye Compression Amp type 842678 in for repair. Just hoping someone has the service manuals or at least the Schematics for these units & would be kind enough to send them to me."|
|30-Apr-12||DRD/5 desk||Tim Barrett has a complete DRD/5 desk that he would like to get back to working condition (not for sale, sorry!) - see the pictures on picassa at https://picasaweb.google.com/petebarrett1. He would appreciate any documentation on the DRD/5 or the GP/4 amplifiers that it uses. He says "we have the BBC monograph from 1956 but it would be great to find some service manuals or circuit diagrams so we can get this beauty working".|
|9-Feb-12||Painton faders||Tom Hakava is looking for Painton faders. Type GS 100 345 or GS 100 349. Any leads or comments greatly appreciated.|
|1-Dec-11||Gain adjustment on AM7/12||Flavio Encinas writes: "Now I'm ready to mount all of the units I have after testing the power supplies (all test perfect), but still missing a couple of details. On the pdf that you have sent to me there is a gain adjustment on AM7/12 modules that I don't know how to set, if it needs an external pot or if its a link I have to add between pins 8 , 10 and 11. If you can search for this information will be good for me. I'm still looking for any info on PS2/167 and nothing came up yet if you can find some will be fantastic. Thanks a lot."|
|10-Nov-11||TE1/7 transistor tester||
Sykes is seeking information on the TE1/7 Transistor Tester.
Click the thumbnail to enlarge.
|10-Nov-11||Unidentified early BBC Camera||
Brian Summers writes: "In
this picture of the experimental colour studio, the smaller of the
two cameras is unidentified, the larger is a Marconi three-tube 3" IO
RGB camera the BD848. The unidentified camera is a bit of a conundrum,
in the early 1960s colour cameras were Huge! and this camera is very
compact for a colour camera at that time. To me it has the look of a
Marconi. From the size it must have used Vidicons in a two or three
I have asked the most likely person to know, who suggested it might be a Philips LDK2 precursor, I'm not so sure myself. There seems to be 2 camera cables at the rear, possibly BICC Mk4b, it was common at the time for colour cameras to have more than one cable. This would have given 6 co-ax circuits back to the CCU, R,G & B plus Live Drive (scan?) and return viewfinder.
If anyone can help with the identity I would be very pleased. I have not seen this one before and have no other pictures of it. The original pictures came from Michael Barrett.
Subsequently Brian added: I have found a bit more about the camera, it is a Philips 3 x Plumbicon experimental camera. There is a picture and a short description in the "SMPTE volume 73 page 475". There is also a reference to the Philips technical review 25 1963/64 no. 6/7 which may have an illustration.
|10-Nov-11||Request for restoration||
Jake Clark-Darby writes: "I recently obtained some equipment from
a storage clearance from one of the engineers from Radio Caroline.
Amongst some other things I have a rack with:
1x UN10/47 telephone control and balance unit
1x AM20/4 program peak level meter
2x AM6/18 limiting amplifiers
(All in a 2U rack with power supply.)
I would love to use this equipment in my studio and although it powers up it does not seem to function properly. Would somebody be willing to restore this equipment for me?
|10-Nov-11||Mixer from BBC Radio Bristol||Ahmed of Studio 1999 writes: "Has anyone ever seen a mixer like this before? Its not like any BBC desk I have ever come across. Apparently it came out of BBC Radio Bristol. It is 12 channels and stereo with bass, treble, pan, echo and cue send on each channel. All the pcb boards have 'acorn' written on them. Any info much appreciated as I hope to begin to bring it back to life soon!|
|10-Nov-11||BBC master clock, model CA1/6A/118||Robert Wilkes collects electric master clocks and has an old BBC master clock model CA1/6A/118 together with an SE1/1 changeover unit. He has managed to get it running again, but this was difficult without circuit diagrams etc. So, he is seeking any information such as circuit diagrams, service handbook and operating handbook. The circuit boards are marked with the following part numbers: AM24/1 (amplifier PCB), OS2/41 (oscillator PCB), UN1/160 (frequency divider PCB). He would also like to know what approximate year it would date from.|
|7-Nov-11||Rolls Royce Radio!||David Adams would like to know if anyone can identify this picture (click to enlarge) and the occasion. He writes "It is a local Daventry photo obviously of the boy in front of a BBC vehicle. The Rolls Royce Club have identified as possibly a Phantom II or 20/25 chassis which were of used for hearses and ambulances etc. They suspect it was later obtained and modified as a BBC publicity vehicle possibly post 2nd World War. I wonder if it was to advertise the new Third Programme which started transmission from Daventry on MW in March 1950. The BBC Photo Archive are currently scratching their heads as are the RR Enthusiasts Club. The photo is in the Daventry Town Museum Photo Archive".|
|7-Nov-11||HF transmitting station on Antigua||Dave Porter is seeking the answer to this question from Mike Cooper. "DXLD coverage of the closing of the BBC Caribbean service makes me wonder whatever happened to the relay and monitoring station the BBC had on Antigua. The antennae, located on the eastern side of the island, were impressive. I vaguely remember hearing that the site was to be put up for sale years ago, but have heard nothing since. I wonder about the equipment (transmitting, receiving, antennae) and the land. Perhaps a DXLD reader has some insight? (Mike Cooper, Apr 3, DXLD)"|
|25-Oct-11||LSU10 speaker cabinet||Jimmy (London) is seeking a BBC LSU10 speaker cabinet(LB8).|
|23-Oct-11||DRD5 transciption turntable||Jimmy (London) is seeking information on the DRD5 studio BBC transciption turntable unit circa 1956. He has the upper part of the unit and is searching for the drive electronics and/or cabinet.|
|18-Jun-11||BBC Engineering Manuals||Chris Friedlander has kindly offered to provide information from various BBC Engineering manuals, within reason, on request: BBC Engineering Practice, BBC Technical Instruction S10, London Control Room operations manual. The equipment described in these publications was replaced by the BBC many years ago. Click here for more information.|
|7-Mar-11||ME16/3 standard level meter||Chris Friedlander has an ME16/3 standard level meter (the thermocouple AC one) and is wondering if there is any maintenance / calibration / schematic info around for this. According to the pcb the design drawing number should be D40934. He says that the unit seems to be working perfectly (after a long-ish warm up) and giving accurate readings. However, as with all these things, having service information would be wise insurance.|
|See the top of this page for links to items that have expired (after one year) or been resolved|