Robison's Manual of radio telegraphy and telephony for the use of naval electricians (1918)
Robison, S. S. (Samuel Shelburne), b. 1867, United States Naval Institute, Todd, David Wooster, Hooper, Stanford Caldwell · Annapolis, Md. : The United States Naval Institute · leaf 147
Fia. 88.—Audion. to 4000 meters, and additional calibrated loading coils for very long wavesare supplied. With very loose coupling the wave length of received signals can thus beread directly. 200. Fig. 89 represents receiving circuits for continuous oscillations;it shows the receiving telephone… … Fig. 89.—Federal Co (Poulsen) In using undamped oscillations for wireless telegraphic purposes itmust be remembered that the frequency of the oscillations themselves istoo high to be heard in the telephone connected with the ordinary re-ceiving circuit, and when the circuit at the sending station…
