RF-attenuator from 1W 2512 size resistors with both BNC and SMA connectors. Works OK from DC to 30MHz.

Measured with NanoVNA-H4 using NanoVNA saver.

PCB size: 71.5 x 25 x 1.6 mm

PCB Stackup: Two layer FR-4 (No impedance control)

Traces are not 50 ohm as this is mainly for < 50 MHz use and the size of the entire PCB is thus significantly smaller than the wavelength at this frequency.

I tried to only use resistors from the E12 series as much as possible.

Two parallel resistors are used for each position for increased thermal handling and to achieve a resistance closer to the calculated values.

Made to fit the following heat sink.

Heat Sink, 4.4 °C/W, TO-218, TO-220, TO-247, 42 mm, 38.1 mm, 25 mm

Farnell Order code 1710612

• Schematic is in the plots folder.
• Link to RF Attenuator calculator
• Link to Parallel Resistor calculator

Connections:

• R1//R2//R3//R4 (input side, to ground)
• R5//R6 (top of Pi network)
• R7//R8//R9//R10 (output side, to ground)

DNI = Do Not Install