The HP 150A Oscilloscope

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The HP 150A Oscilloscope,
A Vintage Symbol of the HP Entry into the Oscilloscope Business


The beginning of oscilloscope production at HP was marked a change in the overall company philosophy.
In 1955, sixteen years after the company's birth, the Hewlett-Packard catalog listed nearly 250 measuring instruments of every type except one -- the oscilloscope!
At the time, Tektronix oscilloscopes were top of the line and the Tektronix Company had built an enviable reputation for superb quality and reliability. The focus at HP was on the dramatic opportunities in the communications business and Bill and Dave's philosophy was not to build a "me-too" product, however they finally approved a modest oscilloscope development program at HP.
The first two products were the HP 130A and 150A. The 130A was a slick DC to 300 kcs low-frequency scope that filled a niche that Tektronix didn't occupy and the 150A was a 10 Mcs, dual channel plug-in design, which at that time was deemed general purpose.



The HP150A Oscilloscope - HP Memory Project Collection



Dave Packard and Bill Hewlett on the HP 150A Production Line
Photo from the video "ORIGINS" - Courtesy of the Hewlett Packard company



HP 150A Oscilloscope

The Ending Fifties,
General Purpose Oscilloscope


Introduced in the April 1956 issue of the Hewlett Packard Journal, the HP 150A had the following main specifications:

  • SWEEP: 0.02 µsec/cm to 15 sec/cm in 24 calibrated ranges
  • SENSITIVITY: 5 mV/cm to 50 V/cm with Model 151A amplifier
  • PASS BAND: DC to 10 Mc - Rise time less than 0.035 µsec
  • COUPLING: AC or DC - 1 megohm shunted with 40 µµf
  • AMPLITUDE CALIBRATOR: 18 cal voltages 0.2 mV to 100 V
  • CATHODE RAY TUBE: 5AMP - 5000 Volts acceleration
  • INTENSITY MODULATION: Terminals on rear panel
  • PRICE: 150A Oscilloscope $1000.00 - 151A Amplifier $100.00


    Made for Accessibility, and . . . Serviceability


    The HP150A had a high number of convenient mechanical features. One of these was the physical layout of the instrument. As shown below, on the unit of the HP Memory collection, the instrument is constructed so that sub-assemblies are mounted on swing-out panels. Such an arrangement gives a high order of accessibility to components and wiring.



    The HP150A Oscilloscope


    The Very Beginning of Etched Circuit Techniques (PCBs)


    The HP 150A electronic circuitry is made of 52 vacuum tubes. Circuits are constructed in sub-assembly form and all of these sub-assemblies are interconnected with plug-in type wiring. Most sub-assemblies are constructed using etched circuit techniques.
    The cathode-ray tube used in the Model 150A is a type 5AMP. This tube was one of the modern monoaccelerator designs which was especially suited to measurement work because of their reduced distortion. Due to the quantity of vacuum tubes, the instrument is fan cooled with filtered air so that components are operated at low temperatures. A thermal cut-out supplements the cooling system to guard against accidental air stoppage.



    The HP150A Oscilloscope - Inside View



    The HP150A Oscilloscope - Inside View - Working



    The HP 150A in the 1956 Catalog


    Cover of the 1956 Short-Form Catalog, Courtesy of the Hewlett-Packard Company


    Page 4 of the 1956 Short-Form Catalog, Courtesy of the Hewlett-Packard Company


    Page 5 of the 1961 Short-Form Catalog, Courtesy of the Hewlett-Packard Company


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