Choice RF Attenuator 9K-6G Digital Attenuator 63.5dB Rotary Encoder Control RF Step Attenuator for LORA 868

ARW637 0–63.5dB Digital Step Attenuator – 9KHz–6GHz, Rotary Encoder Control, USB‐C, SMA

Product Description:
This digital step attenuator is based on the ARW637 chip, offering a wide attenuation range of 0 to 63.5dB with selectable step sizes of 0.5dB, 1dB, and 10dB (adjustable via a rotary encoder with push‐button). It operates from 9KHz to 6GHz (chip supports 8GHz, but FR4 PCB limits practical upper frequency to 6GHz). Powered by 5V USB Type‐C , it features SMA female connectors. The attenuator is bidirectional (no directionality) but lacks internal DC blocking– the RF signal must have zero DC component. Ideal for protecting test equipment, increasing dynamic range, and testing power amplifiers, LNAs, and receivers. The enclosure is 3D printed (minor cosmetic imperfections may exist).

Key Specifications:

• Frequency Range: 9KHz – 6GHz

• Attenuation Range: 0 – 63.5dB

• Step Sizes: 0.5dB, 1dB, 10dB (selectable by pressing the encoder)

• Control: Rotary encoder (rotate to change attenuation, press to change step)

• Max RF Input Power: +24dBm CW (0V DC)

• Supply Voltage: 5V USB Type‐C

• Accuracy: ±1.8dB

• Insertion Loss: 2dB (min) – 9dB (max) – see characteristic curve

• Impedance: 50Ω (all ports)

• Connectors: SMA female (outer thread, inner hole)

• Bidirectional: Yes – input and output interchangeable (no directionality)

Important Notes:

• No internal DC blocking – ensure RF signal has zero DC offset.

• FR4 PCB material limits upper frequency to 6GHz (chip supports 8GHz, but loss increases).

• The enclosure is 3D printed – slight surface imperfections may be present.

• Attenuation
  settings above 40dB are measured with limited dynamic range
  (entry‐level VNA). Measurements will be updated with better equipment
  later.

• Insertion loss is inherent to all variable attenuators (mechanical or electronic) – not a defect of this product.

Applications:

• Protecting spectrum analyzers and receivers from high power

• Adjusting signal levels in RF test benches

• Gain adjustment for amplifiers and LNAs

• Increasing dynamic range in measurement systems

• Educational labs and ham radio stations

Actual measurement chart:

1: Insertion loss

2. S21 curves for several gears