HP8601A loop hybrid reproduction

Designed by sv3ora

Here is my homebrew version of the rare loop amplifier hybrid in the HP8601A sweeper. If the E1 amplifier is faulty, you won't be able to change the frequency or sweep. With the discrete 2-transistor circuit shown on the right and by removing the input resistive divider I was able to fix the unit. This has been lots of hours of debugging for the problem and testing quite a few amplifier circuits, to achieve the gain and bandwidth needed. Enjoy!

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