HINTS

Shannon News, 6 January 1928, Page 4

HINTS

An ordinary large battery-connec-tion clamp is useful to skin rubbercovered stranded hookup wire. Merely file the jaws of the clamp smooth, and then cut in them, with a threecornered file, a notch which is roughly the size of the wire. To use the tool, simply close the jaws over the wire to be skinned, squeeze with the fingers and at the same time pull outward toward the wire’s end. The edges of the notch will pare the rubber insulation off neatly without cut ting any of the fine strands of wire. I'se rigid sockets for the receiver in an automobile. The set is subjected to continual vibration when placed in a car and if the valves are placed on cushion spring sockets there will be danger of valves striking solid objects which, for the sake of space conservation, are placed as close as possible together. A satisfactory arrangements of sockets is to fasten a number of rigid sockets on a shelf which is suspended on springs or a strip of rubber, affording flexibility and shock absolution. This method, however, necessitates more space than is usually available in subh receiv-

Oovered or insulated wire may be used for aerials, the reason being that the insulating coating offer's no more opposition to radio waves impinging oil the antenna wire than would tire air ’which would occupy its place, In fact, insulated wire has the advantage of keeping the surface- of the wire bright and clean, and since radiofrequency currents travel on the surface and not through the body of the conductor, tliis is a decided advantage. Enamelled stranded aerial wire for thq foregoing reason, has proved highly efficient in practice.

In building a receiver employing radio frequency the filament of the radio frequency valves should be controlled by separate rheostats. When the radio frequency valves and the ’detector valve are connected to the same rheostat, one of them may he getting too much current, while the others may be working at their best. The detector requires a grid return to the A positive. The amplifiers require an A negative connection. When one rheostat is used to control all valves ,the grid bias is controlled by the position of the arm on the rheostat When the bias is used for the detector it may not be correct for the radio frequency. The audio frequency valves ai’e not critical to filament adjustment and may be controlled by one rheostat -of proper value.