Volume 3, Issue 8, August 1932
Index of content:
3(1932); http://dx.doi.org/10.1063/1.1748953View Description Hide Description
The fundamentals of field intensity measurements are summarized. The general methods of using a receiving set and a source of voltage for calibrating are outlined. The methods are then extended in application to a radio receiver which utilizes a modified superheterodyne circuit. The resultant beat note is of low frequency, and may be greatly amplified by means of audiofrequency stages of amplification. This gives the receiver not only extreme sensitivity but also great selectivity.
In other methods of measurement, the apparent field strength depends on the amount of modulation of the incoming wave. In the method here described, the beat note with the carrier wave is so great, compared to any contribution of the side‐bands, that the meter readings do not change by any noticeable amount when a transmitting station ceases to modulate and transmits only the carrier wave. The beat note with the carrier wave is so great that it is possible to make measurements on stations whose fields are so weak that they cannot be detected on an ordinary receiver.
The attenuator is of the capacity type with a range of voltage from less than 1 microvolt to 3×106 microvolts. Detailed descriptions of the receiver and attenuator are given, as well as the methods of calibrating the apparatus.
3(1932); http://dx.doi.org/10.1063/1.1748954View Description Hide Description
3(1932); http://dx.doi.org/10.1063/1.1748956View Description Hide Description
3(1932); http://dx.doi.org/10.1063/1.1748959View Description Hide Description
Closed end manometers utilizing organic liquids instead of mercury have the disadvantage that gas dissolves in the liquid and eventually accumulates in the closed end. A manometer is described with which the removal of gas from the liquid and from the closed end is quickly and effectively accomplished.
3(1932); http://dx.doi.org/10.1063/1.1748960View Description Hide Description
3(1932); http://dx.doi.org/10.1063/1.1748961View Description Hide Description