VOLTMETERS USEFUL

Radio Record, Volume I, Issue 13, 14 October 1927, Page 15

VOLTMETERS USEFUL

HINTS FOR BUILDERS. When building a set now it is the desire of the fan to have as neat a looking outfit as it is possible for him to build. The more professional-looking the set the better pleased the constructor is with it, There is one thing which adds to the appearance of any radio set, and that is the addition of a voltmeter. Some fans wish to use an ammeter, but this is not necessary. Besides adding to the general appearance of a set the voltmeter is a useful instrument on any tube receiver. Valves Are Critical. The reason for this is apparent when one knows that valves of to-day are critical to the voltage used to light the filament, and not to the amperage. For long life it is necessary that the valve be burnt at a voltage equal to the rating on the carton in which the tube came. The amperage of the valve is taken care of in the tube itself. Besides the filament voltmeter there are no instruments that are of any great assistance in a set unless very fine work is to he done; in that case a plate milliammeter is an aid to fine adjustment. To Select a Voltmeter. In picking the voltmeter for a set the size and rating depend upon two things, the panel space, for size, and the number and type of tube for rating. In using storage battery valves such as the UX-201A or C-301A the rating of the voltmeter must be seven volts or slightly higher. ° Using WD-11, 12; C-11, 12 the voltmeter should have a range of two volts, For the UX-199 or C-299 valves the range of the volimeter shonld be four volts, Of course, it is possible to have the scale reading of the voltmeters used higher than that suggested above, but this is not advisable, because the higher scale the harder it is to obtain a fine reading on the low voltages,