Radio Digest (July 1924-Apr 1925)

November 29, 1924 RADIO DIGES T— Illustrated 19 Helpful Hints to Get the Most from Radio Chapter XI — Care of Radio Batteries By Thomas W. Benson ITS THIS series of articles set operation will be told in so simple a manner that the uninitiated can follow instructions and get the most out of reception, whether or not he knows anythingabout electricity or its application to broadcasting and reception. The next two articles of the series will be: Chapter XII — Telephones and Iioud Speakers. Chapter XIII — Hints on Tuning*. THE batteries are the power plant of the Radio set and upon their condition depends much of the pleasure and efficiency of Radio reception. When a set fails to operate properly the first thing to do is check the batteries and make sure they are in good condition. A discharged A battery will cripple the best receiver ever built and a B battery that has fallen off in voltage will cause most multi-tube sets to howl while reflexes will fall off greatly in range, although the volume is cut but slightly. We will consider the A and B batteries separately while discussing their care and proper operation. Much has been written in these pages on the proper method of connecting and charging storage A batteries, so little need be said on this phase of their care. We will consider then how to get maximum service and life from the battery. Heating is one of the worst enemies of long life. Never charge or discharge a battery at such a high rate that it heats up over 120 degrees F. Heat causes the plates to buckle, loosening the paste in the plates and reduces the capacity of the battery. The same is true of jars and jolts. Don't slam the battery around or drop it. The automobile type of battery may stand this treatment, but many of the Radio batteries are built with thin plates and will not stand this treatment. This is one argument against sending batteries out to be charged; one is never sure of the treatment they receive and it is Laboratory Tested and Approved Lincoln Low-Loss Condenser Lincoln Low-Loss Grounded Rotor Condenser, 23plate model Is most efficient electrically, strongest mechanically. Several radical improvements. List price $4.50. Lincoln Oscillascope The "superhet" depends for efficiency on its oscillating circuit. The Lincoln Oscillascope permits such delicate control of oscillations that it produces amazing results. List price $6.50. Lincoln "Long 45" Tuner Condenser, inductance and tickler coil all in one. Add a socket, rheostat grid-condenser and leak . . . and you have a wonderfully efficient complete set. Coast-to-coast range with clearness of reception equal to big expensive sets. List price $10.00. Lincoln Collapsible Loops Correctly designed mechanically and electrically. Insures quality reception . . and is most convenient. List price $6.50. The Lincoln Collapsible FourPoint Tapped Loop is ideal for "superhet" and other radio-frequency circuits. List price $8.00. The Lincoln Kit Includes the "Long 45" Tuner. Everything for a 1-tube set with coast-to-coast range. Easy to assemble, easy to add to. List price $21.50. Write for Catalog All Lincoln products fully guaranteed. If your dealer cannot supply you, order direct giving his name. Write for illustrated catalog giving full descriptions. Lincoln Radio Corporation 224 N. Wells St. Chicago, HI. practically impossible to detect mistreatment. Keep the Battery Clean and Dry When nearly fully charged a battery will gas and give off an acid spray that settles on the tops of the cells. This spray forms a conducting surface that drains the battery. It is, therefore, good practice to wipe off the top of the battery occasionally with a rag wet with ammonia water. This neutralizes the acid and checks corrosion of the terminals and battery box. It is necessary to have good connections to the battery at all times so the terminals must be kept clean and free from corrosion. The simplest preventive is to smear the connections with vaseline, but they will corrode in spite of this and must be cleaned often by scraping a/id wiping with an ammonia soaked rag and recoated with the vaseline. A word about specific gravity. An automobile starting battery is usually 1,250 or 1,300 on full charge. This is because the battery is intended for work where currents of 150 amps, are drawn at times and the battery must have practically' no resistance, to stand the current surge. The high density acid naturally shortens the battery life but it permits the use of a smaller battery for a given load. On the other hand Radio batteries operate with a slow discharge rate with frequently long periods between charges. This duty permits of the use of a lower density electrolyte with a gain in battery life. Therefore if a starter battery is used for Radio the acid can be reduced in strength. The proper method of doing this is to give the battery a full charge, pour the acid out and dilute it down to 1,200 with distilled water and refill^ the battery. This will give a longer life to battery by reducing tendency to sulphate and the destruction of the separators. The battery will now read 1,075 when fully discharged. The usual notations on the hydrometer showing full charge and discharge are now disregarded. Vne kind qfjetters Vn(ndg2&M=g$S'$i 8 -^ Nairn U*S Cinci»«att' n metric ^-C°-' Tbordarson ^ Chicago, Itt tested Gentlemen Land^d • ik every x-v l transpractical yency «a d PAR* Efficiency of Dry Cells The portability and compactness of receivers using dry cells for filament current source has resulted in their widespread adoption. To obtain full service from dry cells the Number 6 size cell should not be given a greater load than % ampere. Higher efficiency is obtained by working the cells at half this load and it is economy to use twice as many cells are, in fact, moist cells and a warm multiple. It is general practice to place the batteries close to the set but when this means keeping them in a warm room it tends to shorten the battery life. Dry cells are, in fact, moist cells and a warm place drys the cells out. When the receiver is used in the home it is usually possible to mount the batteries in the basement where it is cooler. The same facts should be kept in mind when dealing with B batteries of the dry cell type, it being doubly important to mount them in a cool place because the cells are smaller and will fall off in voltage more rapidly. When both A and B batteries are placed in the basement the leads from the 'batteries may be brought up through a section of elevator signal cable. This cable is carried by most electrical jobbers and is low in cost. By using a common wire for the negative B and positive A it will require a 4-conductor cable and if the A ground is used it can be run in the same cable. Under no condition attempt to run the aerial lead with the battery leads, for the capacity effect between them will drain all the incoming energy. Storage Cells for Plate Voltage The use of storage cells for plate voltage is entirely practical and economical when a source of charging current is at hand and only troublesome when they must be carried out to be recharged. The rules suggested for storage A batteries should be followed in caring for these cells, particularly in regards to keeping the 'connections clean. The charging rate on the cells should be kept down to the rate recommended by the manufacturer, for the tendency is to charge them at too high a rate, causing spraying of the electrolyte and heating of the cells. Since the reserve space for solution is small in these cells they should be examined once a week and refilled with distilled water. There are a number of devices on the market that utilize house lighting current to produce the high voltage plate current and some are very effective. They operate on two general principles, in one the current is rectified and filtered by condensers and inductances to give a smooth flow of current, in the other current is generated by a series of thermocouples heated by the lighting current. It is always well to test these devices on one's set before making purchase. They sometimes introduce a loud hum in the receiver or cause it to whistle badly because of the resistance present. On some receivers, they function very well and if not overloaded are economical and efficient. The Alkaline Battery The ruggedness of the Edison or alkaline battery and freedom from destructive fumes has led to its adoption for plate batteries and despite its low efficiency as a storage cell it gives satisfaction when properly handled. Its disadvantage is that the voltage falls off steadily from fully charged to empty and thus causes variations in the results from the set. This may be overcome by having several extra cells that can be switched in as the voltage falls, thus keeping the voltage practically constant. Alkaline cells should be fully charged on each charge, partially charging them is of no use for they often drop it in a few hours. 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