702 
Orel) = 
These difficulties of field work underline the importance of mutual 
understanding on the part of the man who develops the equipment and the 
man who uses it. The former should know what will be required of the equip- 
ment, and should have field experience; the operator should have some knowl- 
edge of the basic principles of the equipment in order to use it intelligent- 
lye When a new type of measurement is to be undertaken, the design of needed 
electronic equipment must be based on knowledge of field requirements and 
what is reasonably possible. 
The actual design should then be developed to meet the requirements 
with a minimum of adjustments and a maximum of reliability, Large safety 
factors should be allowed, to take account of such things as tube variations, 
tolerances of component parts, leakage currents, Good mechanical layout 
and construction and clean wiring may mean the difference between servicing 
in the field and stopping work until laboratory repairs can be made, It is 
also worth while to use standard and readily available components as far as 
possible. 
The completed instrument should be tested under actual or simulated con- 
ditions and these results kept recorded as a part of the service record, on 
the instrument. Routine tests and inspections of all equipment are valuable 
in maintaining it at peak performance and avoiding breakdown. 
