About Variable Condensers

Radio Record, Volume II, Issue 7, 31 August 1928, Page 28

About Variable Condensers

Permcrarsy ROM thé early semi-circular form of the plates in variable condensers the shape has gradually evolved in four distinct stages, the straight-line frequeney being the third. In this pattern the plates are made long and thin, the object being to space the stations more widely apart on the dial and nvoid the crowding of most ‘stations into a small portion of the dial, as was the case in the earlier. types. At the lower end of the scale there is very small capacity increase that this type proves very susceptible to outside capacities, which thus tend to disturb the calibration line. This, however, is

there are. few stations on the low@r wave-lengths, except when condensefs are to be worked in gangs. A fourth type, the logarithmic midline, is now in extensive use as being the happy medium between the straight line frequency, and the straight line frequency wave-length types. With this type it is possible to set several condensers to read the same on any one wave-length, and they will then give identical readings all round the dials, so that working in gangs is greatly simplified, enabling two or three condensers to be operated with one control. not a great objection, especially