Dummy Antenna

Receivers are aligned on signals furnished by a "Service Oscillator" or "Signal Generator" because that is the only method of obtaining truly satisfactory signals of constant tone, of adjustable strength, and of the desired frequencies.

In order to make allowance for the effect thai the outside antenna will have on the alignment of the receiver, a substitute for the antenna called a "Dummy Antenna" representing the average antenna is used to connect the service oscillator to the antenna connection of the receiver.

On frequency ranges up to 1700 KC the average antenna is essentially a capacity of 200 MMF if used on a high-impedance primary. It has an inductance of a few microhenrvs but this small inductance can be neglected except in the case of aligning receivers having a low-impedance primary or a Hazeltine low-impedance ccapacity coupling.

On frequencies above 1700 KC, the average antenna can be represented by a 400-ohm carbon resistor.

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