Operation [top]: 1. Connect condenser detector to input.; 2. Connect telephone to output.; 3. Decrease grid leaks to minimum resistance.; 4. Set filament controls at OFF position.; 5. Turn on A Battery by pulling out snap switch.; 6. Increase filament current of last tube to almost full value.; 7. Set filament control knobs of other tubes to index marks. (Never turn past these marks.); 8. Increase grid leak resistance until maximum amplification is obtained.; 9. No further attention is required.

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Size: 1278px × 1564px
Photo credit: © Aclosund Historic / Alamy / Afripics
License: Licensed
Model Released: No

Keywords: 980604--7726d-002, air, airplanes--research--photograph, america, archive, armed, army, bureau, collections, defence, force, forces, military, national, navy, reportage, service, serviceman, servicemen, soldier, standards--history--photograph, states, united, usa