Power Supply

The Web-888 must be powered using a USB-C power adapter. These days, this type of power adapter is often provided with smartphones. The Web-888 draws over 1A and peaks at around 1.5A. A Type-C charger marketed as a 'Fast Charger' is preferred as they generally offer higher current.

Be Careful When Using Precision Bench Supplies

Ensure that the current limit is set high enough (≥ 2A) to handle the peak current requirements of the Web-888. Precision supplies react much more quickly to over-current situations compared to ordinary linear supplies, which use large output capacitors to handle peak current demands. A bench supply will instantly drop the output voltage when the current limit is reached, leading to issues like random shutdowns, TF card write failures, and repeatable server "freezes" during certain operations.

Under-Voltage Due to Cable Voltage Drop

The Web-888 will fail to boot if the 5V input drops below approximately 4.75V. Worse, a momentary increase in peak current draw can cause the input to drop below 4.75V due to losses in the cable, resulting in unexpected power downs or hangs. This is often caused by cables with insufficient wire gauge. Please use high-quality USB Type-C cables.

Noise Reduction with a Quiet Linear Power Supply

Using a quiet linear power supply to power the Web-888 can significantly reduce received noise, especially on the LF/MF bands. Most small line-powered units are switch-mode power supplies (SMPS) with inadequate filtering. Their switching frequencies typically range from 20 to 170 kHz, with harmonics extending into the shortwave bands. Unregulated oscillators result in unstable carriers that can span many kHz. While their emissions may meet regulatory requirements, they can still cause significant interference when used to power an SDR directly. Refer to this article for a comparison of the emissions and safety of common 5V USB SMPS chargers.

Challenges with Transformer-Based, Regulated Linear Supplies

Transformer-based, regulated linear supplies are now more difficult to find, particularly the wall-mount (plug-pack) type. This is partly due to new energy conservation laws requiring higher standby-mode efficiency from power supplies. It is easier for an SMPS to draw minimal current when plugged in but not in use, compared to a transformer-based supply, which has unloaded losses even when not connected. Additionally, SMPS units generally offer better conversion efficiency. Also you have to create a DC-USB converter in the most time even you find a linear power adapter.