Teardown, Repair and Analysis of an HP 8562B 22GHz Spectrum Analyzer

In this episode Shahriar repairs an HP 8562B 22GHz spectrum analyzer. This spectrum analyzer has two input bands. The lower band which operates from 1kHz – 2.9GHz shows does not operate correctly and does not display any signal. The internal construction as well as the operation of the unit is explained along with a close look at LO distribution, input attenuator, dual-mixer and various filters.
During the debugging procedure it is also discovered that the Second Mixer is also damaged in this unit. A replacement unit was purchased however a replacement unit for the main first converter is too expensive to replace. As an alternative, a Mini-Circuit mixer is used as a replacement. The LO signal is routed to the external mixer via a microwave switch. In this configuration the LO is automatically switched to the correct mixer for each frequency band of operation. The unit is then verified for correct operation.

3 comments

  1. RaoulEvilD says:

    Thank you for this great video.

    I am wondering where do you get the internal diagrams of your instruments?

  2. Ron Curry says:

    Great video. However, to answer your question as to why you are seeing all the spurious signals…. It’s because the so called “dual mixer” is MUCH more than just a simple mixer. If you disassemble one you’ll find that it’s quite a work of art with lots of microstrip filters as well as ceramic filters and tuned transmission lines to allow passing only the IF frequency. That said, without adding the appropriate bandpass filtering your method of repair using a simple balanced mixer just isn’t going to get you a useful SA. You can pickup replacement dual mixers on eBay for around $350-$400 and it’s really the most economical way to go. The HP 856x series specs are quite good as are the 859x series (if they have the right options) and a more modern equivalent (in terms of specs) will cost you many, many times more than you can get one of these machines for. They are a quite useful solution for those of us who don’t want to pay $10k-$15k just to get an LCD and a bit lighter weight! Thanks again for your videos. Always enjoy them!

  3. tasweet says:

    as always great video. i like the way you use some new technology to replace the technology that is too rare. thank you

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