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Measurement of two attenuators

I purchased a used attenuator. Model JFW 50FA0-030-100

Presumably it has the following specifications:

Connectors Type N
Attenuation 30 dB
Impedance 50 Ohm
Continuous power 100 W
Frequency range 0 to 3 GHz
The attenuator could for example be implemented as a pi network. Looking into the input, you see 50 ohm impedance from both the left and the right side. Click: full size
The attenuator is heavy and round, impractical because it rolls off the table. I therefore screwed feet onto both sides. These also protect the connectors. Click: full size
Click: full size
Type N connector, female side. Click: full size
Type N connector, male side. Click: full size
I measure the attenuation using an affordable NanoVNA V2 Plus4.
Before the measurement, the VNA is of course calibrated.
Click: full size
Attenuation from male side to female side. 100 kHz to 300 MHz. The attenuation is very accurate. The datasheet specifies +-0.5 dB DC to 3 GHz. Click: full size
Attenuation from female side to male side. 100 kHz to 300 MHz. The attenuation is very accurate. The datasheet specifies +-0.5 dB DC to 3 GHz. Click: full size
Additionally, I measure a very small attenuator.
Mini Circuits, MCL-BW S20W2+ 20dB 2W DC-18GHz 0843. The datasheet specifies -0.5 dB to +0.8 dB from DC to 18 GHz.
The measured deviation is smaller.
Click: full size
Click: full size
Click: full size
Great, the attenuators are usable.