Reflex receiver

Reflex receiver from the 1914 Schloemilch and Von Bronk patent.[1] The single triode vacuum tube amplifies the radio signal, then also amplifies the audio modulation signal extracted from it by the detector.

A reflex radio receiver, occasionally called a reflectional receiver, is a radio receiver design in which the same amplifier is used to amplify the high-frequency radio signal (RF) and low-frequency audio (sound) signal (AF).[2][3][4] It was first invented in 1914 by German scientists Wilhelm Schloemilch and Otto von Bronk,[1] and rediscovered and extended to multiple tubes in 1917 by Marius Latour[5][3][6] and William H. Priess.[3] The radio signal from the antenna and tuned circuit passes through an amplifier, is demodulated in a detector which extracts the audio signal from the radio carrier, and the resulting audio signal passes again through the same amplifier for audio amplification before being applied to the earphone or loudspeaker. The reason for using the amplifier for "double duty" was to reduce the number of active devices, vacuum tubes or transistors, required in the circuit, to reduce the cost. The economical reflex circuit was used in inexpensive vacuum tube radios in the 1920s, and was revived again in simple portable tube radios in the 1930s.[7]

  1. ^ a b US Patent no. 1087892, Wilhelm Schloemilch and Otto von Bronk Means for receiving electrical oscillations, filed March 14, 1913; granted February 17, 1914
  2. ^ Lee, Thomas H. (2004). The Design of CMOS Radio-Frequency Integrated Circuits, 2nd Ed. UK: Cambridge University Press. pp. 15–18. ISBN 0521835399.
  3. ^ a b c McNicol, Donald (1946). Radio's Conquest of Space. Murray Hill Books. pp. 283–284. ISBN 9780405060526.
  4. ^ Langford-Smith, F. (1953). Radiotron Designer's Handbook, 4th Ed (PDF). Wireless Press for RCA. pp. 1140–1141.
  5. ^ US Patent no. 1405523, Marius Latour Audion or lamp relay or amplifying apparatus, filed December 28, 1917; granted February 7, 1922
  6. ^ Grimes, David (May 1924). "The Story of Reflex and Radio Frequency" (PDF). Radio in the Home. 2 (12): 9–10. Retrieved January 24, 2016.
  7. ^ "Reflexing Today: Operating economy with the newer tubes" (PDF). Radio World. 23 (17). New York: Hennessey Radio Publications Co.: 3 July 8, 1933. Retrieved January 16, 2016.