FORMS OF MECHANICAL CONSTRUCTION 



controls of the unit may still be operated as usual, since knobs and dials remain 

 in place when the cover is removed. By pulling out the connectors and un- 

 doing two further thumbscrews, a unit may be pulled clear. Because the 

 construction is 'inside-out' with respect to a conventional chassis, a wide 

 solid-angle of access is possible to the connections of small components, 

 facilitating speedy alterations or additions: also, and for the same reason, 

 the units are very easy to make. There are no horizontal surfaces, and so 

 ventilation by convection is good. 



The unit in Plate 26.6 contains 1 1 valve-envelopes (4 Dekatrons, 4 double- 

 triodes, 3 trigger-triodes) and their associated circuitry, yet no difficulty 

 was experienced in laying out the components within the available space. 



328 



