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Radio Corporation Of America Radiola 25 Instructions Manual

Super-heterodyne
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Radiola 25
Super-Heterodyne

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Summary of Contents for Radio Corporation Of America Radiola 25

  • Page 1 Radiola 25 Super-Heterodyne...
  • Page 2 Radiola 25 REG. U.S. PAT. OFF Super-Heterodyne...
  • Page 3 Instructions 86982 Edition F Radio Corporation of America 233 Broadway New York City 10 South La Salle Street 28 Geary Street Chicago, 111. San Francisco. Cat|...
  • Page 4 REG. U.S. PAT. Off. Super-Heterodyne INTRODUCTION RADIOLA 25 is a radio broadcast receiving instrument, utilizing the super-heterodyne principle, which provides unusual simplicity of operation, selectivity and sensitivity. The cabinet contains the operating mechanism and battery equipment, as well as a socket for the loop antenna which is plugged in through a hole in the top cover, making the receiver self-contained, with the exception of the Loudspeaker.

  • Page 5: Equipment Required

    The information herein is illustrated to show each step in the installation of Radiola 25. Read the instructions first, then follow the pictures, with accompanying descriptions, when making the installation.
  • Page 6 BATTERIES REQUIRED The following batteries are required for complete dry battery operation. .—The fact that the Radio Corporation of America does not list NOTE batteries of all manufacturers is not intended as a reflection on the products of any battery manufacturer not listed. Any battery having dimensions, ratings, and satisfactory terminal connections, similar to those of the batteries listed below, may be used.

  • Page 7: Installation

    Station Selectors. Raise the lid of Radiola 25 to the vertical position, permitting the stay arm to hold it open. Remove the red shipping clamp which holds the tube socket unit during shipment, by taking out the four round head screws.
  • Page 8 nuts and replace them if the receiver is shipped at a later time, to prevent the swaying of and possible damage to the spring-supported tube socket unit. Installation of Batteries. When making connections to the batteries, do not permit the metal terminals on any battery connector to come into contact with the terminals of other battery connectors, with other battery terminals, or with the metal framework of the set, even for a short time.
  • Page 9 The battery connections described herein are also shown on the "Instruction Card" fastened to the inside of the cabinet cover. Place ”B” Batteries in Cabinet and Push Them Toward Front Fig. 4. Location of 22 ½-volt "B" Batteries . - Throughout this booklet, where two or more wires are connected to NOTE a common terminal, the color identification of this group of wires is by means of the color of the particular wire on which the metal marker tag is clamped.
  • Page 10 VOLT BATTERIES Radiola 25 as follows: Set one of the 22 ½ -volt plate batteries (see paragraph B- l, pages 5 and 14) on the table at each end of the cabinet, and connect the four cable leads according to Fig. 3. Place the batteries in the cabinet (Fig. 4), setting them down upon the bottom next to the side, and then pushing them forward to the front of the cabinet.
  • Page 11 Place “C” Batteries on Top of Left-hand "B" Battery Fig. 6. Location of "C" Batteries 45-voLT "B" : Place the two 45-volt plate batteries (see INSTALL THE BATTERIES paragraph B-2, pages 5 and 14) in the two rear corners of the cabinet, and connect the four cable leads as described in Fig.
  • Page 12 Connect (+) 45 Maroon to Connect (-) Black to (+) 45 Post (-) Post Connect (-) One Yellow Connect (+) 45 Two Maroon with Red Tracer. One and Red, One Black to Black with Red Tracer to (+) 45 Post (-) Post Fig.
  • Page 13 There will be found six pairs of leads coining out of the cable just above these batteries, one of each pair being a short lead, the other a long lead. Connect each of the short leads (+A) to the central (positive) binding posts of their respective batteries.
  • Page 14 Insert Five Radiotrons UX-199 in Sockets l to 5 Fig.11. Insertion of Radiotrons UX-199 Turn the " "' pointer P to " ". Pull out the VOLUME CONTROL LOUD filament switch K. Then turn the " " pointer F BATTERY SETTING slowly to the right to 3.5.
  • Page 15 " pointer F to " ", push BATTERY SETTING in the filament switch K, and close the lid of Radiola 25. F G H J K L M N P Fig.13. Radiola 25 with Batteries and Radiotrons Installed Six "A" Batteries (see page 5) Two 22 ½...
  • Page 16 Fig. 14. Insertion of Loop Insertion of Loop. Unpack the loop for Radiola 25, which conies in a separate container. Handle the loop with care, preferably holding it by the center spindle to avoid damage to or stretching of the wires. Push the projecting center spindle of the loop through the loop socket hole (Fig.

  • Page 17: Operation

    OPERATION Clips for Measuring Filament Voltage Fig. 15. Location of Controls Loudspeaker. The phone plug of a Loudspeaker, such as Radiola Loudspeaker Model 100 or Radiola Loudspeaker Model 104, should be inserted in the second stage telephone jack (Fig. 15). The first stage telephone jack may also be used for Loudspeaker operation at reduced volume.
  • Page 18 " pointer slightly toward the left to compensate for this rise SETTING in voltage. Tuning. The tuning of Radiola 25 involves only the manipulation of the two drums G and N on the Station Selector Control L (Fig. 13), a simple operation after the principles described below become thoroughly understood.
  • Page 19 It is recommended that the right-hand drum N be consistently set at the "lower peak" in the manipulation of Radiola 25. (When this is done, the gradu- ations showing the settings of the right-hand drum will...
  • Page 20 (2) Two distant stations on the same frequency may be separated by rotating the loop, provided they are not in the same general direction from Radiola 25. Set the loop on Radiola 25 where best results are secured, trying to locate a position where the interference or undesired signals do not come in, but the desired signals do.

  • Page 21: Maintenance

    Fig. 16. Calibration on Station Selector Drums To calibrate make a short dash on each dial drum immediately opposite the center indicator and mark the station call letters opposite each dash. MAINTENANCE Radiotrons. It is good practice to keep one or more spare Radiotrons of each type on hand for emergency use.
  • Page 22 than is necessitated by the condition of the "A" battery or by accidental short-circuit of the "B" battery through the filaments. When the filaments are operated at too high a voltage (" " pointer advanced too far), the active material in BATTERY SETTING the filaments is rapidly driven off, and the useful life of the Radiotrons and batteries is considerably shortened, without...
  • Page 23 Filament or “A" Battery. There are several indications by which the user may determine that the filament or "A" battery is becoming exhausted. These are low filament brilliancy, weak signals, and distortion, the signals becoming less and less recognizable, When it is found necessary to turn the " BATTERY "...
  • Page 24 Fig. 17. Wiring Diagram of Radiola 25 .—In this wiring diagram, two or more leads of a like color contained in the same cable may be distinguished NOTE by the numeral following the color designation at each end of a given lead.
  • Page 25 SIMPLIFIED LIST OF BROADCASTING STATIONS For Complete Lists See Newspapers or Radio Magazines Freq. in Call Wave- City State In the Freq. IN ANOTHER CITY K.C. length in KC. Same Call City . State Meters City 1000 WPG WLIB 299.8 Atlantic City.
  • Page 26 379.5 WGBU KVOO Bristow.... .Okla. WMBF 384.4 Miami Beach..Fla. WEAR WHAZ Troy....N.Y. WTAM 389.4 Cleveland..Ohio +f1r» Wn cTl WLIT 394.5 WOAI Philadelphia..Pa. San Antonio..Tex. WHAS WJY 399.8 WCAP fKHJ \ WOR Louisville..Ky. C WCCO 405.2 New York..
  • Page 27 STATION LOG DATE AND CALL LOCATION FREQUENCY STATION SELECTORS TIME LETTERS KILOCYCLES LEFT HAND RIGHT HAND...
  • Page 28 (3) for use with licensed talking machines and licensed radio broadcast receiving devices; and only where no business features are involved." Radio Corporation of America...