As we continue to work our way through our archive of photos, we run across some that are a bit out of the ordinary.  They may be humorous or unique but they stand out from the other photos. We post new photos here monthly with the previous photos in the slideshow.

Our May Photo of the Month is of a Type 310A oscilloscope, showing off a remarkable mechanical design that allowed ready servicing of its densely-packaged components. The 4 MHz Type 310 portable oscilloscope started as a prototype shown to IBM in response to their request for a high performance, lightweight portable scope to be used for field service.

In 1954 Frank Hood was assigned as project engineer and a working model was approved by IBM.

Frank Hood

John Kobbe also contributed to the design with his idea of using a floating power supply to solve the problem that brightness changed, sometimes dramatically, after varying the duty cycle.

John Kobbe

The 310 first appeared in the March 1955 catalog. It weighed only 23.5 lbs. and sold for $595 (about $7,100 in 2025 dollars). Frank recalled in his memoir that as a specialized instrument the expectation was 310 sales would be limited. However, tens of thousands of 310 and 310A scopes were sold through the last catalog appearance in 1972. These were built under either the Tektronix logo or that of IBM.

The 310 was introduced employing Tektronix first circuit boards, but with the introduction of the ‘A’ model in the May 1959 catalog, the design returned to an extensive use of ceramic strips, clearly seen in the photo. Note also the view of the working portion of the Tek-made axial switch in the upper left corner, introduced in the Type 315, Tek’s first portable scope. This innovation, the invention of machinist Jim Morrow, was widely used on Tektronix oscilloscopes to consolidate functionality and maximize the spacing between rotary switches on the crowded front panels of the company’s early instruments.

Jim Morrow

The 310A employed a Tektronix-made cathode ray tube, the T3100. Note how the CRT is angled upward in the chassis for better viewing. Given the tight component spacing, an accessory, the FB310 Fan Base, was offered for $25 to provide addition cooling where the instrument was to be used for extended periods at elevated temperatures. The wedge-shaped base raised the front of the scope to enhance viewing further.

Photos of the Month:  Jan 2025 - Present

Photos of the Month:  Feb 2019 - Dec 2024