Marconi Mk III TV camera production line is re-born

Paul Marshall reports on an ambitious project – on a small scale

Since the beginning of lock-down, hardly a day has gone past when some aspect of the old main Marconi Chelmsford works hasn’t been re-invented here at our base near Lincoln.

Marconi’s gigantic New Street works was an integrated facility – raw materials and small components went in and finished equipment went out. Facilities here have become something like a miniature New Street – the old Section 15 wiring shop, Section 169 (‘TV Test’) and a host of support services. Although there’s nothing as grand as Building 720 Canteen, there is a kitchen staffed by one (my wife Jill!). We have seen so many of the old factory functions live again in terms of metalwork, paint shop, wiring and assembly and final test, albeit on a tiny scale.

Recreating the 1950s

The reason for all this activity has been the drive towards completion of Project Vivat, BECG’s recreation of a 1950s Marconi-equipped BBC television OB (outside broadcast unit). It generates huge demands in terms of recovery from essentially scrap electronics to working equipment.

The goal is a fully functional unit with three working cameras restored to a standard as close as possible to mid-1950s practice. It will be the oldest fully operational OB truck anywhere in the world and it has to be right. The process has required a large investment of time, money and resources not just into the truck itself but also in restoring and testing a huge amount of mid 1950s Marconi broadcast television equipment. All the restored items must be safe, as authentic as possible and reliable for proper use.

Some of these goals conflict and it’s a question of balance – new components or refurbish, exposed live terminals or cover, re-paint or call it ‘history’? Just as vintage aircraft are best appreciated when flying, period outside broadcast trucks and their cameras need to be seen working.

The resolution of a complete camera channel being tested. Cyril Teed of test division has this camera trained on a special transparent photograph of a picture which might be seen in a normal outside broadcast. It is Ilford’s picture of Kersey Village, and it has test lines superimposed on it ‘The Marconi Companies and their Peoples’, Vol 6, No. 7 February 1956 p20.
Lens turret assembly in Section 15. J. Warner, chargehand centre, with R. Wood, right, who is fitting turret bearings, and G. Murdy, left, fitting the filter ring ‘The Marconi Companies and their Peoples’, Vol 6, No. 7 February 1956 p18.

Star attraction

Of course, it’s not just about cameras. There’s all the support equipment including vision and sound mixers, monitoring, communications and test facilities. That said, the working cameras will always be the star attraction.

With most of the restoration of support equipment complete, attention in the last few months has turned to bringing all three cameras up to operational status at as high a standard as possible. There’s enough raw material for up to six working camera channels, but for now it’s just the three required for Project Vivat. The minutiae of decisions taken on a daily basis can be overwhelming but staying focused on the goal has been a good motivator. Nowhere has this been more apparent than in the work to produce the truck’s three fully operational Marconi Mk III 4½” Image Orthicon TV cameras.

On the production line

The need for three cameras has meant working as something like a production line in terms of refurbishment and testing. We have changed many hundreds of defunct 60-year old capacitors, replaced and dressed wiring, and carried out deep cleaning and painting. We have sourced damaged and missing components and done in-depth technical testing to ensure correct functionality. Where possible and appropriate, we have built test jigs for sub-units that are best tested on the bench. These include ones for viewfinders, low-noise head amplifiers, power supplies and picture monitors. New Street lives again!

Paul working on a Marconi Mk III camera head.

First pictures

Camera 3 is now going through initial test and by the time this article appears, it will have produced its first pictures. That’s the three cameras done apart from minor issues such as ‘why doesn’t the iris meter work on Camera 2?’ which will become items for the pre-delivery snag sheet. Fortunately, BECG is the customer and we won’t be facing the dreaded factory acceptance test.

Actual picture from Camera 1 looking at a test chart.