order to attain maximum performance from the receivers, it was found desirable to test them frequently under actual operating conditions, as installed in a ship or aircraft. Since it was usually impractical to transport bulky test equipment to the operating site, the test instrument had to be a single small unit, simple to use and capable of operating from a wide variety of power sources. The unit developed by General Radio to fulfill this requirement was later manufactured by the Fairchild Camera and Instrument Company* to General Radio drawings, and bore the service designation, TS-47/APR Test Oscillator.
As can be seen from the panel view in
Figure 1, the oscillator was unusually small and compact. The unit shown, containing a tunable oscillator, a modulator, an a-c power supply, and a built-in antenna, was housed in a moderately well-shielded case. The dimensions were only 10" x 8" x 11" overall and the weight about 15 pounds. Oscillator tuning was controlled by a single knob, and the dial indicated the operating frequency directly within ±1%. The frequency range between 40 and 500 megacycles was covered on the fundamental of the oscillator with a maximum output of at least 5 mw at frequencies below 400 Mc and a somewhat lower output at higher frequencies. The output signal was rich in harmonics, and relatively strong usable signals were present up to frequencies of about 1500 Mc. Since only rough performance checks were required, no provision was made for monitoring the power output, but a simple output control was included. In order to make the instrument as generally useful as possible, internal circuits were provided for amplitude modulating the carrier with a 1000-cycle sine wave or a fairly long pulse.
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