Radio Broadcast (May-Oct 1926)

Parts of Real Quality Dominate the New A ijtanee uver time ujferings oj Improvements for Existing Receivers and a Wealth of Parts for Those Who Are Building New Sets A S THE value of mechanical and /\ electrical precision has become better appreciated in every JL JML. branch of the radio art, parts built with watchmaker's precision have become the rule rather than the exception. The days of touching condenser plates, transformers which might better be called low-frequency filters and rheostats with self-removing resistance windings have practically disappeared. The 1927 offerings of parts manufacturers represent new standards in accuracy and soundness of construction and present the experimenter with opportunity to make the most advanced type of receiving equipment. Parts may be considered in two general groups: (1) those which may be used for the improvement of existing receivers, such as trickle chargers, automatic power supply switches, socket power supply devices, audio-frequency and power amplifier systems, loud speaker and console cabinets; and (2) elements which go into the receiving set itself, such as variable condensers, transformers, dials and a vast array of miscellaneous small parts. The performance and convenience of existing sets can be greatly improved by the installation of some of these various new devices. The storage A battery, for instance, need no longer engage the constant attention of the broadcast listener and experimenter if he equips it with a device like the Apco Full Automatic Converter. By plugging the proper terminal into the light socket, connecting the storage battery to another pair of terminals and the filament supply leads from the set to a third, the storage battery may thereafter be practically forgotten. The converter automatically places the battery on charge when the set is not in use and it also disconnects the charging device when the charging process is complete. Kodel has brought out a Chargometer which automatically disconnects the charging device when the battery is fully charged. Another convenience is the Brach Controlit which permits of the installation of the storage battery and charger at a point remote from the set. When the set switch is turned on, the charger is disconnected and the B battery circuit automatically switched in. When the set is switched off, the Brach device turns on the trickle charger which maintains the A battery at full charge. The National lead battery people have brought out a trickle A charger and battery unit and also a 2-ampere Tungar outfit. Willard and Philco present their A battery trickle charge outfits, having a constantly visible hydrometer to show the battery's condition of charge. There is a wide range of charging devices which meet^every possible condition with which the radio user may be faced. For those having only 110 volt d. c. available, there is the Ward-Leonard Trickle charger. The Unitron electrolytic charger, offering three different charging rates, selected by a switch, is available in styles suitable for 25, 40, and 60 cycle power supply. Other excellent chargers are offered under the trade name of France, Kodel, Liberty, Valley, Westinghouse, and numerous others. In the field of B battery substitutes are so many meritorious products that it is quite impossible to so much as list them in this brief review of what may be seen at the shows. They vary from outfits like the smaller Apco and All-American devices, with a fixed amplifier output and variable detector voltage, to the Sterling, with its three variable outputs for low, intermediate and high voltage, sufficient to power any standard type of tube, including the ux-210 and supplying also two ranges of C battery voltage, one of 3 to 9 volts and the other of 40 volts. All sorts of intermediate combinations, most of which are equipped with variable detector voltage, one or more fixed or variable amplifier voltages, are available to the user. The manufacturers making several models include such popular names as Acme, Apco, Grigsby-Grunow-Hinds, Kodel, Majestic, Glenn L. Martin, Mayolian, Timmons, and others too numerous to mention. In the field of the chemical rectifier, B battery substitute devices may be mentioned the Balkite in various models, delivering 90, 135, or 150 volts maximum, according to the need of the user, and some also combined with A battery power supply units. In this field also is the Willard storage B battery, combined with their previously mentioned A battery unit. Another device along these lines is thi Philco, which has enjoyed very wide sale. For those desiring to construct their own B battery substitutes, the necessary chokes and transformers, or complete kits ready for assembly, are exhibited by Thordarson, Pacent, Ward Leonard, Silver-Marshall, Apco, Acme, and others. Lest it be concluded from the foregoing that the B battery is a thing of the past, attention is called to the strides made in B battery construction in the past few AUTOMATIC DEVICES FOR CONTROLLING THE A BATTERY Four devices from Apco, Brach, Kodel, and Willard. The Apco arrangement is designed to keep the A battery at maximum charge automatically. The Brach "Controlit" enables the switch of any set to control automatically the operation of B substitute and battery charger. The Kodel "Radio Chargometer" is an automatic switch which disconnects the battery when it is fully charged. Price $10. The Willard Power Unit charges the A battery automatically and also controls B battery charging