The January Advertisement of the Month comes from the January 1953 issue of Electronics. It features a photo of Tek engineer John Kobbe demonstrating the portability of the Type 315-D, Tektronix’s first compact scope. Introduced in the March 1952 short-form catalog with a rated bandwidth of 5 MHz and weighing only 36 lbs, the 315-D offered features only found previously in laboratory instruments at the time.

Frank Hood initiated the design after the company moved to the new Sunset Plant in 1951. Dick Ropiequet came up with a new sweep circuit that dramatically improved stability and accuracy. It was the topic of one of Tektronix’s first patents. John Kobbe came up with an innovative direct-coupled, unblanking circuit. The smaller size of the instrument meant there was less room for controls on the front panel. This led machinist Jim Morrow to propose making some of them co-axial, i.e. a shaft within a shaft operated by separate knobs. After failing to find an external vendor, these switches were made in-house, including the plastic knobs. This co-axial control became a standard feature in Tek scopes to follow.

The 315-D was the first Tektronix instrument to use ceramic strips to support and organize components. This was the idea of Ted Goodfellow and was also awarded a patent. The DuMont 3-inch round CRT was later replaced by Tektronix made CRT. The “D” designation noted the inclusion of a delay line in the vertical signal path. The 315-D sold for $770 in the March 1953 catalog ($9,400 in 2025). It last appeared in the March 1957 Tek catalog.

Advertisements of the Month: Sept 2025 - Present.