Rectification Record of KT1025A Bluetooth Audio Chip for Treadmill in KC Certification FCC Test at Luxshare

I. Problem Description

The testing agency Luxshare reported that the sample sent by the customer failed the wireless KC (Korea) test, mainly in the following two aspects:

1. The receive spurious of the Bluetooth part does not meet the standard.

2. The Bluetooth transmit power is low.

The testing environment includes the customer's PCBA motherboard, and a power supply board is not within the shooting range.

II. Detailed Handling Process

2.1 Testing with Power Supply Only to the Bluetooth Part

• Receive Spurious Test: Set the FCC's PC tool to "RX" and click send. The test result shows normal.

• Transmit Power Test: Set the FCC's PC tool to "TX" and click send, with the channel set to 0. The test result is normal.

Generally, only the upper limit of transmit power is concerned. The test result this time is 3dB, which is good. However, many certifications require that the transmit power should not be lower than - 3dB.

2.2 Testing with the Whole Board Powered by Battery

• Receive Spurious Test: Set the FCC's PC tool to "RX" and click send. The test result is normal.

But a signal of more than 900 MHZ is detected to exceed the standard. It is judged that the laboratory was not closed, and it may be the mobile phone signal of someone else that was detected.

• Transmit Power Test: Set the FCC's PC tool to "TX" and click send, with the channel set to 0. The test result is normal.

2.3 Testing with the Whole Board Powered by the Customer's Complete Power Supply (AC220 to 12V)

The receive spurious test result is normal. Although the transmit power was not photographed separately, it is also in a normal state.

III. Summary

1. Spurious Problem: It may be caused by the use of USB to TTL (CH340G) or the wrong wiring by the rectification engineer. It has not been verified yet, but the test has passed.

2. Insufficient Transmit Power Problem: The rectification engineer from Luxshare connected the antenna wrongly. The shield wire was connected to the antenna, and the antenna was connected to the ground, resulting in insufficient transmit power.

Tags: #KT1025A Bluetooth Audio Chip #KC Certification #FCC Test #Rectification Record