Vacuum Tubes in Wireless Communication; A Practical Textbook for Operators and Experimenters

Vacuum Tubes in Wireless Communication; A Practical Textbook for Operators and Experimenters

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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1918 edition. Excerpt: ... the plate circuit of the second valve is tuned by the coils L-5, L 6 and the condenser C-5, an untuned circuit may be employed. It is not always essential in a system of this kind that the plate circuit of the first valve be tuned to the incoming radio frequency currents, but for the best signals it is of prime importance that the grid circuits of both valves be thus tuned. This is accomplished mainly by condensers C-1, and C-3, the usual secondary condensers. Variation of L-2, L-3, LA, P-1, etc., is necessary to obtain a wide range of frequencies. In practice, the coupling of transformer M-l is very close and is usually fixed. Very careful adjustment of the couplings M or M-2 is necessary, or otherwise the valves will be set into self-oscillation at an audio or radio frequency. Summarizing the functioning of the circuit of Figure 47: (1) The incoming radio frequency oscillations are repeated in the plate circuit of the first valve and amplified through the regenerative coupling M, then impressed upon the grid of the second valve through M-l, and further amplified through coupling M-2. (2) This amplified current is rectified by the valve action between G and F and over the duration of a wave train a charge piles up in the grid condenser C-4. (3) The charge in this condenser raises the potential of the grid to a high negative value, reducing the plate current. (4) At the termination of the wave train this charge leaks out the grid condenser and the plate current returns to normal value. This variation of the plate or telephone current occurs at an audio frequency. This circuit will function with or without the grid condenser C-4 of the second valve. A battery with a potentiometer may be connected in the grid circuit and the potential of the more

Product details

  • Paperback | 48 pages
  • 189 x 246 x 3mm | 104g
  • Miami Fl, United States
  • English
  • black & white illustrations
  • 1236494113
  • 9781236494115