AERIAL AND GROUND

Daily Telegraph (Napier), Volume 58, Issue 179, 30 August 1929, Page 14

AERIAL AND GROUND

DISCAEDING THE EOEMER. 3 Tany people to-dny Iiave sets in their lionies wJiicli do not strictly require the use of an aerial at all, but in niost instances tliey have erceted oue, as au aerial terminal screw has been provided. Tliey are generally not aware of any other sonrce of radio frequency potential that will operate the set. Sets opcratino; on the lighting cireuit, as all np-to-date machines do, liave two separatc ground conneetions — one fi-oni the electrie line and the other from the regnlar ground system. These two grounds ai'e at different radio frequency potentials, due to the faet that the radio waves induce a voltage in any length of nietallic couduetor; and doing away with the aerial eimply ronsists of using this dift'erence of radio frequency potential to operate the set instead of depending upon the voltage indueed in a wire strung up for that purpose. Tt has been learned from experience that sometimes a ground wire, when conditions are just right (or just wrong, depending upon wln'ch way it is viewed), will actually reduee signal strength in a power-operated set with nn aerial in use. This is due to the light line and the ground wire eacli having voltages developecl in them that are out of phase, resulting in a "hueking" action. Since the ligliting circuit cannot be eliminated because of power requirements, it is best to disoard the ground wire altogether in suc-h cases, if the nser pi'efers to keep the aerial. Bv disearding the aerial altogether and conneeting the grouncl lead to the aerial binding post the result will, in most eases, be just as goocl as befote. Sometimes tbey are even iniproved markedlv, but seklom are tliey any worse. This is better tlian disearding the "ground. " wliieli is almost a neeessity on account of 1mm and attendaut noises because the ground lead is a simple installation eompared with the aerial. The ligliting circuit is not connected directly to the circuit of the A and B eliminator. but there is always sufficient electrostatic capacitv between tlie two eircuits" to allow the radio frequency current to pass. Whether or not static will be reduced by tlie use of the two grounds is a mucli niooted question, but at least the static will be 110 worse — if it is less, so mucli the better. Such a sininle tbing to try sboulcl not be overlooked by anyoue owning an A.C. set. Even those with tbe oklei" battery sets. if a B eliminator is in use, may try it. Tbe experiment simply involves disconnecting tbe aerial from tbe set and then cbanging tlie aerial from the set and then cbanging tbe ground wire to tbe aerial binding post. C'heck tbe tnning to see if tbe volnnie and selectivitv bas been impaired or iniproved. and then decide between the two eircuits.