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Radio Record, Volume VIII, Issue 25, 28 December 1934, Page 41

If two resistances cf equal value are connected in parallel with ‘each othei, their effective resistance iys only half that of one of the resisstances. On the other hand, if two ¢qual value resistances are connected in Series, the total resistance is doubled. A certain cure for poor selectivity in a receiver jis to add an, extra tuned cireuit at the aerial end of the set. At least two tuned circuits are needed for a reasonable order of selectivity. Do not run your loudspeaker leads underneath the set or iy. close proxi--mity to the aerial or earth leads, as this is a common cause of unwanted inter-action and audio instability. A flash-lamp bulb maunted in the base of an old valve and connected. to the filament terminals mnakes a very handy tester for checkinjz filament circuits. By dividing the set’s; total filament consumption into the a.ctual amperehour capacity of yom: accumulator, you can tell about how many hours the latter should last withotit recharging. Pick-up leads can be shielded to eliminate instability. The . shielded. covering should be earthed.