Radio Broadcast - 1925, February - 113 Pages ... - VacuumTubeEra

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672 <strong>Radio</strong> <strong>Broadcast</strong>
What Reflex Means 673 might be expected. Here, however, we are dealing with a different problem. In the tickler case we are interested in a very small percentage of the total frequency, that of the incoming signals, say one million cycles. The tuning is so adjusted and the position of the FIG. 2 One of the simplest forms of reflex and one of the best known. The coil in the plate circuit is known to all users of regenerative sets. Some of the radio frequency energy is fed back again through the tickler coil to the primary circuit tickler so arranged that oscillations over this comparatively narrow band can be controlled. In audio-frequency amplifiers, however, we are interested in the uniform amplification of the whole band of frequencies from fifty to several thousand cycles. If the tickler were adjusted for one particular frequency, oscillations would probably occur at another. For code reception where all signals can be brought to a single audible note, say 1000 cycles, the audio amplifier may be made to regenerate in this fashion with remarkable results. In the case of the resistance-coupled amplifier, as illustrated in Fig. 3, part of the output energy of one tube is sent around the circuit again. There are certain precautions that must be taken before such a scheme works, precautions with what the engineer would call the "phase relations." In general such feed back is undesirable because of the difficulty in controlling the system. WHEN AMPLIFIERS OSCILLATE A UDIO-FREQUENCY amplifiers very ** fre- quently do oscillate, a result of some undesirable coupling between the output and the A high pitched squeal may betray this input. state of affairs, but often the oscillations take place at a frequency above audibility. Lack of amplification and some distortion is the result. It is for this reason that all grid and plate leads in multi-stage amplifiers should be as short and as far apart as possible. In practice, then, a frequency changer follows the amplifier that is to be reflexed and it is the greatly changed frequencies that are returned to a precceding part of the circuit to go the rounds again. Fig. 4 shows the general principle. Incoming signals are sent through a radio-frequency amplifier where they are boosted in amplitude. They are then changed ITAfflO( tKKtUOK) r
Page 1 and 2: RADIO ol. 6, No. 4 February. How Mi
Page 3 and 4: ( , me How Michael Pupin Succeeded
Page 5 and 6: . the '; tory. ; Early : scholar. a
Page 7 and 8: How Michael Puj3ih' Succeeded "665
Page 9 and 10: The Way of the Transgressor 667 or
Page 11 and 12: The Way of the Transgressor 669 ver
Page 13: What Reflex Means How One Tube is M
Page 17 and 18: : crystal ! toward : this What Refl
Page 19 and 20: The International Radio Broadcast T
Page 27 and 28: The Listener's Point of View 685 CA
Page 29 and 30: The Listeners' Point of View 687 SI
Page 31 and 32: The Listener's Point of View 689 [p
Page 33 and 34: f syncopation The Listeners' Point
Page 35 and 36: ! of ; an Some Experiences With the
Page 37 and 38: The March of Radio 695 communicatio
Page 39 and 40: The March of Radio 697 tial product
Page 41 and 42: The March of Radio 699 PROMINENT FI
Page 43 and 44: The March of Radio 701 It might be
Page 45 and 46: The March of Radio 703 year the Phi
Page 47 and 48: The March of Radio been bothered by
Page 49 and 50: Who Owns Our Broadcasting Stations
Page 51 and 52: Who Owns Our Broadcasting Stations
Page 53 and 54: "NOW, 1 HAVE FOUND. . A Department
Page 55 and 56: ' . THIS "Now, I Have Found. 713 JO
Page 57 and 58: . "You Our Busiest Dav 7'5 Follette
Page 59 and 60: THE LOSS STABILIZING R. F. CIRCUITS
Page 61 and 62: eceiving In the R. B. Lab. 719 It i
Page 63 and 64: In the R. B. Lab. 721 This resistan
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How to Build a One-Dial Reflex Rece
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How to Build a One-Dial Reflex 725
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THE ANTENNA AT STATION 5IT, BIRMING
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What We Are Doing With Broadcasting
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What We Are Doing With Broadcasting
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A Winder for Small Inductances How
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A Winder for Small Inductances 739
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A Winder for Small Inductances 74'
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Problems of Receiver Design 743 sho
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Our HAT , Readers Write Us A Word f
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The Grid 747 structed as a portable
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RADIO BROADCAST ADVERTISER 749 Set
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RADIO BROADCAST ADVERTISER 751 Grap
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RADIO BROADCAST ADVERTISER 753 No.
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Radio Broadcast - 1925, February - 113 Pages ... - VacuumTubeEra

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