[GreenKeys] HP 3553B - Somewhat off topic

[Harold Hallikainen]

Interesting! What is in the patch box? I see switches for input and output
impedance. Does the patch box output eed to be terminated in 600 ohms? I
suspect that the attenuator is designed for 600 ohms and requires a source
resistance of 600 ohms and a load resistance of 600 ohms. As to what the
patch box impedance switches do, are they PERHAPS selecting transformer
windings to set the input and output impedance of the patch box?

Fun stuff!

Harold
https://w6iwi.org


On Wed, February 4, 2026 5:33 pm, William Wuttke wrote:
> This video is somewhat off topic, but I know a lot of military
> technicians who used these things daily.
>
> https://youtu.be/NDQsOGThb3U
> HP 3553B Portable Test Set Calibration Check
> youtu.be
>
> 73,
> Bill
> KE3BK
>
>
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