The standard signal generator provides a continuously adjustable and accurate radiofrequency signal. Its main application consists in testing radio receivers. It uses a range switch for changing the coils required when operating over a wide range of frequencies. The frequency is read directly on the control dial. Therefore, calibration curves are no longer required.
INSIGHTS
The standard 605-b type signal generator combined good electrical characteristics with a number of operational advantages. To facilitate frequency selectivity measurements, direct reading of the logarithmic frequency ferrule of the carrier was supplemented by a slow-moving dial with frequency increments of just 0.05 percent. Both the inductors and the capacitors in the synchronous circuit of the carrier oscillator were equipped with adjustments making it possible, if necessary, to compensate the deviations for long periods in calibration. Silver contacts were used to ensure a low and permanent contact resistance. Frequency modulation, lateral bandwidth cutting and attenuator setting reaction on the carrier frequency were virtually eliminated from previous models.
With the GR 605-B some requirements were improved in terms of operation and elimination of error sources compared to improvisation in the basic method. In the new standard signal generator the emphasis was on greater practicality and operational accuracy. Compared to the previous generators, where it was necessary to change the coils when operating on a wide range of frequencies, with the GR 605-B, this operation could be carried out in a much more practical way using a range switch. There was also a direct-read frequency control dial, eliminating the need to use calibration curves.
Another characteristic, innovative for those years, was that it offered the possibility to connect the apparatus to the electric mains in alternating current even if the generator could continue to work with the batteries. In addition, frequency modulation as well as the reaction of attenuator setting on the carrier frequency was negligible. The instrument is the result of almost two years of study to solve the problem of the design and production of a signal generator that combined accuracy and general utility with a price within the reach of most radio production laboratories, of colleges and engineers.
Technical Data
- Name of the property: generator
- Type: laboratory instrument
- Vendor: General Radio Company
- Year of production: 1938
- Weight: 31kg
- Size: 600x400x280 mm
Bibliography
https://www.ietlabs.com/genrad_history/historic_manuals
https://www.radiomuseum.org/r/gener_raco_signal_generator_605_b.html
