This is the Telephone exchange and Sound Mixer

On the left is the Engineering Managers desk, it has the 15 line  manual telephone exchange. The outgoing sound lines and good talkback facilities.

On the right is the Sound desk. It has 20 channels divided into 3 groups, provision is made for PA outputs and extensive monitoring. There is no provision for equalisation, it is a flat response mixer. In case of power failure the whole sound chain of the MCR reverted to battery operation.
The Engineering Managers desk had the manual telephone exchange and good talkback facilities.

This picture was taken during construction at Pye's factory

MCR21's Monitor Stack

Just seven 14 inch monitors were deemed to be sufficient, one for each camera, two for engineering and production previews and in the centre the 17 inch transmission monitor. Associated with each 14 inch monitor is a BBC designed waveform monitor. 

Top centre is an Optical PPM, also a BBC design. The idea being that the sound super visor can see the PPM in the same eye line as the transmission monitor.  To either side are the clock and the dual standard off air check receiver. 

This receiver with 405 line VHF and 625 line UHF was installed in advance ready for the start of the 625 line the following year. 

The Vision Enginneers control desks

MCR21 had 4 Pye Mk6 cameras and these are the Operational Control Panels (OCP) for them. Two desks are provided each with a bench seat, seating two engineers each.

From left to right:-
Vision supervisors control panel and two OCPs for cameras 1 & 2. The Tektronix 515 oscilloscope in the middle. On the right, OCPs for cameras 3 & 4, at the end is a blank panel for a future caption scanner OCP. Each Camera has a dedicated picture monitor and waveform monitor.

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A publicty photograph with 2 cameras

This is one of series of pictures taken by Pye to promote their ability to produce a complex, yet flexible outside broadcast van to a detailed BBC specification.

Pye made ten of these, they were known by Pye as “Main Fleet Scanners”. Finishing with MCR28 they were the last of the line of BBC monochrome OB Vans. 

They were significantly more advanced than earlier OB vans. Many new innovations were used for the first time, laying the ground work for the colour installations that were to come in just a few years time.  

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