FCC ID 2A4WD-ZK-ST21
Bluetooth Audio Power Amplifier
by Qingdao Wuzhi Intelligent Technology Co., Ltd.
Grantee Code: 2A4WD Product Code: ZKST21
Latest application date: 2026-04-21
FCC ID Device Details
| FCC ID | 2A4WD-ZK-ST21 |
|---|---|
| Mirrors | fcc.id | gov | fccid.ai |
| Grantee Code | 2A4WD |
| Product Code | ZKST21 |
| Applicant Business | Qingdao Wuzhi Intelligent Technology Co., Ltd. 🇨🇳 |
| Equipment Class | Bluetooth Audio Power Amplifier |
| Test Firm | Shenzhen HTT Technology Co.,Ltd. |
Operating Frequencies
| Frequency Range | Application Purpose | Final Action Date |
|---|---|---|
| 2402-2480 MHz | Original Equipment | 2026-04-21 |
Exhibits
| Document | Type | Available | File |
|---|---|---|---|
| User Manual | Users Manual | 2026-04-21 | PDF 1.1 MB |
| appendix II EUT Internal photo | Internal Photos | 2026-04-21 | PDF 604.2 KB |
| appendix II EUT External photo | External Photos | 2026-04-21 | PDF 942.1 KB |
| Label and Location | ID Label/Location Info | 2026-04-21 | PDF 239.8 KB |
| appendix I EUT Test Setup photo | Test Setup Photos | 2026-04-21 | PDF 412.1 KB |
| Antenna Specification | Test Report | 2026-04-21 | PDF 1.3 MB |
| Appendix RF Test Data for BT | Test Report | 2026-04-21 | PDF 3.2 MB |
| HTT202604437F01_Test Report-BT FCC | Test Report | 2026-04-21 | PDF 2.2 MB |
| USA-CoveredEquipmentLetter-Combined_V1.1 | Attestation Statements | 2026-04-21 | PDF 133.1 KB |
| USA-LocalRepLetter_V1.1 - 2A4WD-ZK-ST21 | Attestation Statements | 2026-04-21 | PDF 514.9 KB |
| Declaration Letter of Model Difference | Cover Letter(s) | 2026-04-21 | PDF 91 KB |
| USA-ConfidentialityRequestLetter_V0.1 | Cover Letter(s) | 2026-04-21 | PDF 118.8 KB |
| HTT202604437F02_RF Exposure-MPE | RF Exposure Info | 2026-04-21 | PDF 459.8 KB |
| Block diagram Metadata only | Block Diagram | PDF 83 KB | |
| schematic Metadata only | Schematics | PDF 206.3 KB | |
| Operation Description Metadata only | Operational Description | PDF 135.1 KB | |
| USA-DueDigilenceLetter_V0.1 Metadata only | Operational Description | PDF 157.5 KB |
Application Information
| Application ID | 89/X5t3mRJHogM3xaSuxjw== |
|---|---|
| Final Action Date | 2026-04-21 |
| Application Purpose | Original Equipment |
| Applicant FRN | 0032008856 |
| Model | ZK-ST21 |
| Frequency Range | 2402-2480 MHz |
| Equipment Class | DSS - Part 15 Spread Spectrum Transmitter |
| Device Description | Bluetooth Audio Power Amplifier |
| Responsible Party | CHENCHEN ZHANG, 780754962@qq.com  , 13538218145 |
| Non-Technical Contact | Cindy Wu, HOORAY INDUSTRY LLC, cindynewhope@gmail.com  , (626) 910-5808 |
| Test Firm | Kevin Yang, Shenzhen HTT Technology Co.,Ltd., info@httprc.com  , 86-755-23595200 |
| TCB Email | o.kneip@kl-certification.de  |
| TCB Scope | A4: UNII devices & low power transmitters using spread spectrum techniques |
| Short-Term Confidentiality | No |
| Long-Term Confidentiality | Yes |
| Modular Equipment | Does not apply |
| Composite Device | No |
| Cognitive Radio | No |
| Authorization Waiver | No |
| Authorization Waiver Approved | No |
| Section 5301 Certification | Yes |
| Related OET Knowledge DataBase Inquiry | No |
Applications
| Application ID | Date | Purpose |
|---|---|---|
| 89/X5t3mRJHogM3xaSuxjw== | 2026-04-21 | Original Equipment |
Equipment Authorization
| Frequency | Output | Rules |
|---|---|---|
| 2402-2480 MHz | 0.0013 | 15C |
Grants
TCB Grant - Application 89/X5t3mRJHogM3xaSuxjw==
| TCB | GRANT OF EQUIPMENT AUTHORIZATION |
TCB |
| Certification | ||
| Issued Under the Authority of the | ||
| Federal Communications Commission | ||
| By: |
|
KL-Certification GmbH Heinrich-Hertz-Allee 7 St. Ingbert, 66386 Germany |
Date of Grant: 04/21/2026 Application Dated: 04/21/2026 |
| Qingdao Wuzhi Intelligent Technology Co., Ltd. |
| No. 438, Xiaoxinhe Road |
| Huangdao District, Qingdao City, |
| Shandong Province, China |
| Attention: CHENCHEN ZHANG , General manager |
| NOT TRANSFERABLE |
| EQUIPMENT AUTHORIZATION is hereby issued to the named GRANTEE, and is VALID ONLY for the equipment identified hereon for use under the Commission's Rules and Regulations listed below. |
| FCC IDENTIFIER: | 2A4WD-ZK-ST21 |
| Name of Grantee: | Qingdao Wuzhi Intelligent Technology Co., Ltd. |
| Equipment Class: | Part 15 Spread Spectrum Transmitter |
| Notes: | Bluetooth Audio Power Amplifier |
| Grant Notes | FCC Rule Parts | Frequency Range (MHZ) | Output Watts | Frequency Tolerance | Emission Designator |
| 15C | 2402.0 - 2480.0 | 0.0013 |
| Output Power listed is peak conducted. RF exposure compliance is addressed for 1.1310 and 2.1091 MPE limits. The antenna(s) used for this transmitter must be installed to provide a separation distance of at least 20 cm from all persons. End Users must be provided with transmitter operation conditions for satisfying RF exposure compliance. |