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HP 200AB Oscillator

Hewlett-Packard's first patented device.
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  • The HP 200AB is a distinctive test oscillator in that its operation is prescribed by William R. Hewlett's master's thesis at Stanford and was protected by the first patent held by Hewlett Packard, #2,268,872. Adjusted for inflation cost : $1500. Prior owner: Case Institute of Technology.

    The HP 200AB is a distinctive test oscillator in that its operation is prescribed by William R. Hewlett's master's thesis at Stanford and was protected by the first patent held by Hewlett Packard, #2,268,872. Adjusted for inflation cost : $1500. Prior owner: Case Institute of Technology.

  • Back faceplate.

    Back faceplate.

  • Ganged variable capacitors, pentode, and 6k6 amplifier. This constituted the oscillator section, with the lamp providing for the "resistance tuning" in the oscillator circuit.

    Ganged variable capacitors, pentode, and 6k6 amplifier. This constituted the oscillator section, with the lamp providing for the "resistance tuning" in the oscillator circuit.

  • Detail.

    Detail.

  • The three tubes on the left constitute the amplifier, and the far right tube is a rectifier. This oscillator uses two 6K6 tubes in push-pull configuration.

    The three tubes on the left constitute the amplifier, and the far right tube is a rectifier. This oscillator uses two 6K6 tubes in push-pull configuration.

  • Detail of anti-backlash mechanism and insulation from the capacitors.

    Detail of anti-backlash mechanism and insulation from the capacitors.

  • Frequency range selector switch.

    Frequency range selector switch.

  • Underside of oscillator pentode.

    Underside of oscillator pentode.

  • Detail.

    Detail.

  • "Top" view.

    "Top" view.

  • The transformer on the right is the mains transformer (highest voltage: 240VAC for plates, fed to the rectifier) whereas the transformer on the left is for output coupling into a 600-ohm load.

    The transformer on the right is the mains transformer (highest voltage: 240VAC for plates, fed to the rectifier) whereas the transformer on the left is for output coupling into a 600-ohm load.

  • All tubes are functional and HP brand (excluding the metal-cased oscillator pentode, which is RCA.)

    All tubes are functional and HP brand (excluding the metal-cased oscillator pentode, which is RCA.)

  • Detail of lamp used for tuned resistance.

    Detail of lamp used for tuned resistance.

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