Teardown, Repair and Experiments with a Tektronix RSA 6114A Real-Time Spectrum Analyzer

In this episode Shahriar attempts a difficult repair of a Tektronix RSA real-time spectrum analyzer. This well-equipped instrument reports several error messages during startup POST including LO Unlock as well as Signal Path failures. The service manual of the instrument does not provide any detailed block diagram and no schematics. Most failures require the instrument to be serviced by the Tektronix factory. The equipment has various advanced options including 110MHz analysis bandwidth, digital modulation analysis, wide-band IF output and deep memory.

The teardown of the instrument reveals a multi-board, multi-module design. The top of the instrument contains all digital blocks and boards while the bottom of the instrument houses the RF deck assembly. The RF deck is broken into various stages such as attenuator, RF switches, first converter, second converter, IF block, reference synthesizer and LO generator. For the purposes of addressing the YIG problems the LO board is examined. The problem is traced to two components, both dividers in the complex PLL system of the LO subsystem. The LO board is fully analyzed and described and the defective components re replaced.

The repaired instrument is tested for various functionality including DPX, de-modulation and measurement of beyond 8GHz CW tones. The instrument passes all self-tests, alignments and detailed diagnostics.


  1. Mark James says:

    I have two of these units. One is fully operational and the other is missing the hard drive. I am unable to figure out how you take it a part for me to clone the drive and put it in the other instrument. Do you have a video of opening it up?

  2. Peter says:

    Great video, totally agree with your comments about the Mantis, wouldn’t be without one in my lab. Up till the mid 1990’s when I bought my first Mantis I used a binocular microscope and would always have neck and back pain after a few hours. The only negative has been the failure of the LEDs in the light strips but these are easy to remove and the LEDs can be replaced with a better part.

  3. rich says:

    Excellent video and walkthrough of the repair.
    Cheers and thanks.


  4. test says:

    I like the cat

  5. Pieter says:

    Got here through a Dangerous Prototypes link and learned a lot about RF of which I’m not that familiar. Your knowledge and expertise in the field really made it worth watching! I’ll be checking out more of your videos.

  6. Vasily says:

    Thanks for the good video. I enjoyed this “real time” bench adventure and find it equally
    good to your more more conventional, prepared teaching videos.

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