Wavelength Calibration

Radio Record, Volume V, Issue 1, 17 July 1931, Page 17

Wavelength Calibration

THE following is my experience in attempting to calibrate my receiver, thus enabling me to- locate stations, previously unheard, first of all from a graph. I found after much experimenting that the wavelength of any station, multiplied by 2/7, minus 44, gave me the dial reading for that station, My three tuning dials (on a five-valve battery set) range from 0 to 100 degrees. The following are a few examples:-1YA, 329 m, works out to 50 degrees on my set. It comes in -at 504, .4QG,. Brisbane, 395 ‘m., works out at 69. On my set it comes in at 69. 2YA, 416.4 m.. gives 75 (nearest whole number), while on my set it comes in at 744, . os Below 2UH (40, 40, 40 on my set), the numbers vary, and the calculation does not therefore apply. This is mainly due, I expect, to there being three dials on my, set. ‘In an endeavour to pick-up my first American I made the necessary calcula-, tion, and tried KGO, San Francisco, I heard it almost immediately. KGO, 380 m., works out to 644, which is the reading at which it comés in. The subtraction number would vary on receivers of differ‘ent makes (using 0 to 100 divisions), but the scheme is still. workable. -For instance, where XYZ might find his dials read 66: for Brisbane, instead of, my 69, he would obviously subtract 47, not 44, as with me. Curiously enough, no other fraction I have tried will produce the even results that 2/7 does. I -discovered it purely by chance.-‘Northern Enthusiast" (North Auckland).