Plug-in Coils

Radio Record, Volume III, Issue 28, 24 January 1930, Page 25

Plug-in Coils

N short-wave receivers utilising ordinary plug-in short-wave coils it is the increasing practice to fix the baseboard aerial coil-holder by one serew, allowing it te be moved to vary the coupling between the verial and the grid or reaction coil. This enables "flat spots" on the tuning condenser to be obviated, and is more efficient than putting a condenser in the aerial lead. When removing coils, special eare has to be taken owing to the fact that, fixed to one side only, the holde: is likely to be pulled from the base. board or the screw-hole broken. Also the coil is not always in line with the others when in a swivelling holder, as the one screw tends to pull the holder to one side. If:a piece of celluloid, mica or similar insulating materia) is eut in a semi-circular shape «nd fixed. with screws, to the baseboard over the unscrewed leg of the coil-holder the eoil may still] be swung round, but the holder is as firm as when fixed with two screws.