The Prototype. Only 1 year later than thought -> NEVER put dates on a frontpanel :-)

The mastermind of this design is of course the Arduino Nano Every. It handles the user input from the keyboard as well as the serial commands and displays the attenuation on the 128 x 32 pixel oled display. The Nano also programs the chain of attenuators.




View inside the case. Not much there ...

The board was designed to fit in an existing case (style 3), milled from Aluminium. It houses 3 F1958NBGK from Renesas (7-Bit 0.25dB Digital Step Attenuator, 1MHz to 6GHz). In order to reduce stray coupling, shields can be installed between the attenuators. With the three attenuators, a theoretical attenuation of 3 x 31.75 dB = 95.25 dB deems possible, but the truth is that the software limits it to 50 dB, as the Amplitude response becomes ugly.

Measurements have been done with a hp8753. Most manufacturers calibrate in position 0 dB - which of course gives more beautiful results, but we wanted to characterize the device, not only the attenuators.

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