B170-V

The B170-V is a 170 Ω attenuator for the 517. Switches select from 0dB to 64dB of attenuation.

John Addis wrote:

The inductors compensate for the switch stray capacitances. When the Ls and the stray Cs are connected like that, they constitute a lumped element delay line. The intent is not to make a delay line, but compensate out all the stray Cs by making a lumped delay line out of it. That extends the bandwidth and makes the impedance 170 ohms (up to 1 GHz or so) rather than a bunch of Cs sitting on the connection from input to output.

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  Hand-trimmed resistors

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  Schematic