AERIALISMS

Sun (Auckland), Volume III, Issue 729, 31 July 1929, Page 16

AERIALISMS

The specific gravity of the cells in an accumulator newly received from the charging station should be about 1.2. When the specific gravity of any of its cells falls to 1.15 or thereabouts the accumulator requires recharging. If voltage or hydrometer readings show that one cell in a four or sixvolt battery is showing readings widely different from its fellow or fellows, this fact should be pointed out when it is returned to the charging station, so that it may receive special treatment when recharging. Apart from spilling or leakage, a certain amount of the electrolyte in an accumulator is lost by gassing, so that a supply of distilled water should be kept on hand to make good this loss. Never let the litfle holes in the plug at the top of an accumulator become stopped up, as these play an important part in allowing the battery to “breathe.” L.T. batteries should be kept clean, cool and dry, and the terminals should be kept coated with petroleum jelly to prevent them from being attacked bv the acid. Never place new acid in an accumulator to make good the losses caused by evaporation, etc. Only distilled water should he used for this purpose. It is not good practice to tap a four or six-valve battery so that certain cells are doing more work than the others, unless special precautions are taken to give these cells an extra charge when recharging is done. When calibrating a two-dial set it is better to pay particular attention to readings of the high-frequency or anode dial rather than to the aerial dial, as variations are more likely to affect the latter than the former. A two-volt battery is fully discharged when the voltage reading is 1.8. A four-volt battery is fully discharged when the voltage reading is 3.6 and a six-volts accumulator when the voltage is 5.4 As a rough and ready test as to whether a set is oscillating or no, there is much to be said for the oldfashioned method of wetting the finger and tapping the aerial or grid terminal of the valve, when very loud clicks will denote oscillation. Never join up an L.F. amplifier to a set unless you make sure that the H.T. negative connection inside the amplifier goes to the same L.T. lead, i.e., either negative or positive, as in the set to which the amplifier will be attached. If an amplifier is to be used with a valve set and its internal connections cannot be checked for any rea- ' son, its H.T. negative terminal should not be joined up at all. Generally this is not necessary.