NOTES

Shannon News, 22 November 1927, Page 4

NOTES

Lack of sensitivity and volume in a receiving set can often be traced to poor contaci between the socket contact springs and the prongs of the valve. . The exceedingly feeble cur« rents passing through the socket must meet with a minimum of resistance . ar;c' in this respect perfect contact between the prongs and socket is an absolute necessity. A liberal application of a fine grade- of sand paper on the valve prongs will quickly remove any of the corrosion and bad spots which make for a poor contact. It is advisable to clean the prongs at regular intervals.

Crackling and other extraneous noises in a radio receiver may often be traced to dirty contacts or jacks. Perfect contact by the various springs is an absolute necessity. Jacks should be- given a periodical overhauling, and their contacts carefully cleaned: either, by the use of a very fine file.; such as is used for filling points in automobile- timers, or a very, fine grade of sand paper. Care should be taken in the use of the file or sand paper that only the corrosion is removed from the contacts. If too much of the material is removed, the various springs will not make the proper connections.

Often some . "fan" is desirous of knowing which is the plus and minus of his loudspeaker cord tips. Every* one should know that if you connect the cord tips the wrong way round to your loudspeaker you are going -to damage it by weakening the magnet within it. Some imported radio sets do not bear any indication as to which is the positive or negative of the loudspeaker connections. Here is a method of distinguishing which is which. Peel part of the skin off a raw potato. Connect up the batteries to your set, turn on all filaments, take the cord off your lovdspeaker, and. stick the tips of the cord into : the potato. The positive tip will make | a blue stain on the potato. Then con«

nect that tip to the loudspeaker post marked with a cross or a red spot.