Pentrix was a company formed in 1962 in New York that designed plug-in spectrum analyzers for Tektronix oscilloscopes.  Tektronix acquired Pentrix in 1964 to bring out their own line of spectrum analyzers and plug-ins.  This article on Spectrum Analyzers is from Spring of 1965.  Click on the image to read the PDF document.

The museum has four portable spectrum analyzers on display. The first and earliest spectrum analyzer is the Pentrix prototype for the 491 portable spectrum analyzer which Tektronix introduced in 1966.

We also have a Tektronix 1401 spectrum analyzer introduced in 1972 configured with a Sony/Tek 323 oscilloscope on display.  Both the 1401 and the 323 were battery powered and there was hardware to configure them as a single instrument.  This combination was quite popular with cable television companies.

The wire antenna is simply picking up and displaying local FM radio stations.  The horizontal spectrum is 500 KHz per division so this display shows the radio stations separated by about 800 KHz.  The rightmost "bump" shows the characteristic sidebands for the additional HD portion of the FM broadcast.

The museum also has a 496 spectrum analyzer introduced in 1982 on display.  It is configured with a TR503 tracking generator.  The tracking generator is sweeping the same frequency as the spectrum analyzer with its output going through a bandpass filter seen at the bottom of this photo.

The result is an amplitude display of the characteristics of the bandpass filter with about a 5 MHz bandwidth as seen in this photo.

The last spectrum analyzer on display is the 2782 introduced in 1990.  This portable spectrum analyzer moved virtually every performance characteristic far ahead of the competition at that time.  Frequency coverage is 100 Hz to 325 GHz.  The display also features color and initially sold for $65,000.  It is likewise configured with a simple antenna to display local FM stations in the area.

We have two videos on spectrum analyzers in our Video Gallery - 492 and 496 Portable Spectrum Analyzers and 3052 Digital Spectrum Analyzer 1988.