Hints on Securing a Good Ground

Radio Record, Volume II, Issue 22, 14 December 1928, Page 11

Hints on Securing a Good Ground

SUE EULA Le THE aerial, the surrounding air, and the ground, form one huge condenser, and the electricity carrying the signals from the transmitting station rushes backwards and forwards — from the aerial to ground through the set. No one would think for a moment of using a condenser in the set of which the plates were of uneven size and haphazardly put together. Why, then, use such a condenser out of the set. An efficient aerial with an equally efficient ground is the first step to good reception. PTET EL TE EE ET TE TE TTC EET COT CE TU CETE TTC EL ETL TT CT ECEC ETE TET ETUC TET LE LE LTE EE EETE LE LE LE LE LEAL LE EE EL OLA ALE EL ALE LE LA LE LE OLE LE EE LE ELL LE LLE LE RE LE CLE LE LE LE LE EE OLE LE LE LEE EE OEE LE LL LE LEE LL ULE ALE LEE LELALE LEE AL ALAL ALE LE RG LT

a ¢ ONSIDERING the differ- \: | en types of ground connections it is found that these fall naturally into ; three groups. (a) The town water supply or artisan well where the ground is already provided and the connection only is needed. (b) The Pierce system and its modifications (see diagram). (c) Earthed conductors buried well below the surface and kept damp. HESE cannot be classified according to efficiency; so much depends on locality and on the nature of the soil. The Water Pipe. HEN selecting this type the following points should be borne in mind :- {I) Is there going to be a long connection between the ground and the set? If so, abandon it, for the Pierce system, or the earthed conductor with a shorter lead. {II) If the pipe has to travel some considerable distance and has

many joints before entering the ground, it will be very inefficient, for a long lead is undesirable. (III) If the pipe enters dry or sandy soil, a more efficient system would be the earthed conductor, as will be described. (IV) Other than a clamp, there is little chance of effecting a good connection between ground and lead. | Generally speaking -sets are not near water taps, so that it very often pays to adopt a different type. If a water-pipe offends in any of these points it should not be pressed into use, The Pierce System. HE wire that leads from the ground connection on the receiver out through the window ends ata binding post on a porcelain base. From this post twelve wires lead to the. same number of pipes or other pieces of metal embedded in the ground. A leaky automobile radiator used by the originator was sunk in the ground

at the end of the row of pipes, with its caps just above the surface, so that water could be poured into it. Very good results have been reported by this system. It is particularly suited to moderately dry and heavy soils.

CU EEE CCC CELE LC oe Earthed Conductors. HESE, with all their modifications, are becoming very popular, and correspondents have suggested many novel improvements. Notable among these are an old washing copper, with holes punched in it, to which is soldered the seven strands of 7-18th cable, sunk several feet in the ground, has been suggested by a writer from Khan-

dallah. This would be improved by filling the copper with clinkers and installing a down-pipe to keep the clinkers wet. A lavish supply of water improves reception, Another suggestion comes from Picton. This correspondent suggests a drum sunk deeply into the ground and kept filled with water. A modification is a closed kerosene tin, to which is soldered a down-pipe, in order to keep the tin filled with water. To this can be soldered the lead to the set. Another idea was suggested to the writer by a resident of Trentham, but the application of this method may he restricted to a lucky few. A kerosene tin of empty brass rifie shells had been collected, and well earthed, and arrangements provided so they and the surrounding ground would be kept continually damp. There are many other methods, for instance, coiling a bare wire and burying it in a damp: place. A bed of a stream is quite a good place for an earth, providine > short enougr lead can be used,

Ground Lead: THIS is equally as important a8 the aerial lead-in, and the points enumerated should be carefully watch- ed_

CE Use stranded wire equally as thick as the aerial, if not slightly thicker, to compensate for dryness of ground, or any other counteracting factors; 7-18 cable is excellent, as the seven strands can be divided to the different parts of the ground. Keep the lead as short as possible; a long lead adds to the resistance, and impairs efficiency.

Livery joint should be soldered, : each lead soldered to the ground ¢ nections, but when water pipe is this will be found different, so a earth clamp should be used. When the Pierce system is used, soldering to the pipes should be d before they are sunk into the gro By employing the following me no difficulty should be employ Apply raw spirits of salts to w the soldering is to be done. killed spirits, that is, spirits in w zine has been dissolved, paint the per wire to be soldered. ‘Tin the vanised pipe, then solder the two in usual manner, It has been taken for granted the beginner will make a perfe clean joint by filing the surfaces rubbing them thoroughly with s paper.