TECHNICAL RADIO NOTES

Shannon News, 30 March 1928, Page 1

TECHNICAL RADIO NOTES

Valves can now be obtained in ab types which will operate on one diy cell with an expenditure of .00 of an ampere. These should be ideal foi portable sets. Crystals should never be touched with bare hands, as a film is thereby placed on the surface which impairsits sensitivity. - Crystals which have been handled, ,or exposed to air! should be washed in lio{; water aue scrubbed with a nail brush and soap After the soap has been removed ii fresh water the crystal should b« dried in clean blotting paper. Crackling in the loudspeaker is gen erally caused by one of three things A loose connection, a iun-down B bat tery, or a transformer winding aboiu to break. B battery eliminators must be tested with an. extra high > resistance volt meter; even a good quality voltmotc l will give erroneous results "with an eliminator. Falling pff in signal strength i generally due to run-down A or B batteries, or a poor lighting arrestertry operating the set with the arresteidiscormected. To test a bye pass condenser, toad the terminals with a wire connecter to the 90 or 135 volt B batteries. Remove the wire and a minute late; short the condenser terminals with : scrcivdrivcr, if there is a spark tin condenser is correct. Never let wet B batteries run com plotely down, and keep them scrupulously clean and filled with wutor. Catvliiskers should have a pointed end and may be sharpened by mean; of a file, after which the end should not be touched with the fingers. The aerial should never be forgottei as it is the source of many difficulties It must not run parallel to high ten sion wires. It should be well insulated and the lead-in free from contact with any grounded object.