The Tektronix 1L40 is a spectrum analyzer plug-in for 500-series scopes. It covers the frequency range from 1.5 GHz to 40 GHz using four different removable front-end mixer modules.
By default the 1L40 comes with a coaxial mixer, Tek part number 119-0096-00, which works up to 12.4 GHz using a 1N415D detector diode.
Higher frequencies are covered by three waveguide mixers:
- 119-0097-00: 12.4 GHz to 18 GHz
- 119-0098-00: 18 GHz to 26.5 GHz
- 119-0099-00: 26.5 GHz to 40 GHz
Note that the 1L40's display of RF signals is actually back-to-front — lower frequencies are displayed to the right, higher frequencies to the left. This is because the 1st LO is above the input signal frequency, yet the display shows the IF sweep from low to high left-to-right, so the displayed spectrum is inverted.
The 1L40 is also capable of displaying signals in its IF range of 150-250 MHz, because its input is unfiltered so everything passes straight through to the second mixer. In this case, however, the display is left-to-right.
Type 1L40 was produced for only 3 years, making it the shortest-lived letter-series plug-in.
Signals displayed straight through the plugin's 150-250 MHz IF. Dispersion 5 MHz/div, centre frequency 200 MHz. The peak on the left is the local DAB radio multiplex on channel 6B, 183.648 MHz. The hump to the right of that is the local DVB-T multiplex 'Mux 8' on channel 7. Photo taken in Warsaw, Poland, January 2018.