Abstract :
Some broadcast receiving sets now in use cannot be tuned conveniently to stations broadcasting on frequencies higher than 1000 or 1200, i. e., not below 300 or 250 m. The Third National Radio Conference recommended that the broadcast band of frequencies be extended to 1500 kilocycles (200 m). This emphasizes the importance of the production of sets which will tune conveniently at the higher frequencies, and the desirability of information on how to use existing sets so that all stations may be tuned in. The range of receiving sets which employ a single tuned circuit, (i. e., where the antenna is part of the tuned circuit) may be extended to the higher frequencies without much difficulty. This applies both to crystal and tube sets. It can be done very simply by providing a fixed condenser (about 0.0002 microfarad) in series with the antenna which may be switched in or out of the circuit. The settings of the dials are different when the condenser is in and out of circuit. Shortening of the antenna likewise reduces the capacitance and consequently increases the maximum frequency (minimum wave length) to which the set will tune.
