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This excellent signal generator covers the frequency range 10 MHz to 470 MHz in five bands. It was designed mainly for FM applications however limited AM facilities were also available.
The oscillator comprises a TD03-10 disc seal triode associated with a turret style switch that selected the particular inductor for that range. This also couples inductively to the piston attenuator, giving a continuously variable output from 2 microvolt to 200 mV. The entire tuning arrangement is most ingenious (see below).
The individually calibrated frequency dials were initially marked out with a fine pencil whilst listening to the beat from a crystal calibrator. They were then sent to the engraver (a person, not a computer!) for finishing.
The FM facility was obtained using a ferrite reactor modulator, varactor diodes not having yet been invented. AM was obtained by anode modulation of the oscillator valve.
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