SA3SR-20 Replacement: AT-120V, M3933/14-04S

Original Part

SA3SR-20

Fairview Microwave

RF Attenuators 20dB 0 Hz ~ 3 GHz 50 Ohms 2W SMA In-Line Module

Alternative Part

AT-120V

Hirose Electric Co Ltd

RF Attenuators 20dB 0 Hz ~ 18 GHz 50 Ohms 2W SMA In-Line Module

M3933/14-04S

Amphenol SV Microwave

RF Attenuators 20dB 0 Hz ~ 12.4 GHz 50 Ohms 2W SMA In-Line Module

1. AT-120V Substitution Conclusion From the perspective of core electrical parameters and mechanical interfaces, the AT-120V is a viable and higher-performance direct replacement for the SA3SR-20. Both share identical attenuation value (20dB), power handling capacity (2W), and interface (straight plug SMA male/female). The key difference lies in the frequency range: the AT-120V supports 0 Hz to 18 GHz, far exceeding the original part's 3 GHz upper limit. When operating within the original design's frequency band of 3 GHz and below, the performance of the AT-120V—including attenuation accuracy and VSWR—is expected to fully meet requirements. Furthermore, its wider bandwidth provides additional frequency margin for the system, making it suitable for potential future high-frequency application upgrades. Prior to final substitution, validation testing within the actual operating band is recommended to confirm that parameters such as attenuation accuracy, phase consistency, and power handling fully comply with the stringent requirements of the specific application.

2. M3933/14-04S Substitution Conclusion The M3933/14-04S also serves as a viable alternative to the SA3SR-20. It matches the original part exactly in key specifications: attenuation value, power rating, impedance, and mechanical package. The primary difference, again, is superior frequency performance, with its operational range extending to 12.4 GHz, significantly higher than the original part's 3 GHz. In the original low-frequency application scenarios, this component provides ample performance margin, ensuring signal integrity. Additionally, this part is sourced from Amphenol SV Microwave, and its "M3933" prefix typically indicates compliance with relevant military standards or high-reliability requirements. This may offer potential advantages in terms of environmental adaptability, stability, and consistency. As with the AT-120V, targeted bench testing prior to formal substitution is a necessary step to ensure its characteristics—such as attenuation flatness and power-related temperature rise—are fully compatible with system requirements.

Analysis ID: 9DA9-0893000

Based on part parameters and for reference only. Not to be used for procurement or production.