Nova Microwave #1 - RF Cafe Nova Microwave

The Evening Sun Newspaper

Baltimore, Maryland

April 12, 1924


Poor Modulation Cause of Trouble

Large Broadcasting Stations Use What Is Known as Heising System


Coming of Warmer Weather Will Make Distant Entertainment Harder to Pick Up


By Frank Crafman

Radio Editor, the Evening Sun


Remember - For clear audio amplification it is best to use low ratio transformers in all stages.


The system used at large broadcasting stations is the Heising system of modulation and is named after its inventor. In this system almost perfect modulation is obtained. It is known as the constant current system method and it may be added to any radiophone set with slight modification to the present hookup. If a five-watt oscillator is used it is only necessary to have a tube of the kind for a modulator so as to be capable of dissipating an equal amount of energy as quickly as the oscillator.


Can Use Spark Coil


A modulation transformer is used and this can be purchased, or a Ford spark coil can be used. If the coil is used, it should be taken apart and the primary and secondary windings found an heavier wire soldered to them and the coil taped to protect the windings.


Material required is a tube, modulation transformer, microphone and A and  B batteries. The A battery it to use in series with the microphone. The voltage of this will depend on the microphone, some working on five or six volts and others require ten. If too much voltage is applied to some microphones, they "burn up." If instructions are not contained in the package, it will be necessary to experiment for correct voltage. The better the microphone you use, the better the modulation or sound is produced.


Posted February 22, 2018