QYT KT-7900D
QYT KT-7900D Quad Band Mini Mobile Transceiver User Manual
Model: KT-7900D | Brand: QYT
1. Introduktion
The QYT KT-7900D is a compact and versatile quad-band mobile transceiver designed for amateur radio enthusiasts. It offers broad frequency coverage and a range of functions to enhance communication. This manual will guide you through the proper installation, operation, and maintenance of your device.
Nøglefunktioner:
- Mini Size: Approximately 4.96 x 4.05 x 1.85 inches, weighing about 2.3 lbs.
- Frequency Range: VHF 136-174MHz (Rx/Tx), 220-270MHz (Rx/Tx), UHF 350-390MHz, 400-480MHz (Rx/Tx).
- Output Power: VHF 25 Watts, UHF 20 Watts.
- Functions: FM Radio, PTT ID, DTMF, Remote Stun, Remote Kill, Repeater, Alarm, Monitor, High/Low Power Settings.
- Programming: Supports PC04FTDI Programming Cable (compatible with Windows 10/XP).
2. Hvad er der i æsken
Bekræft at alle varer er til stede i din pakke:
- QYT KT-7900D Transceiver Unit
- Speaker Microphone (with DTMF function)
- 2.8 ft DC Cable with Cigarette Plug Connector
- Radio beslag
- Mikrofon beslag
- Monteringshardware
- Programming Cable (PC04FTDI)
- Brugervejledning (dette dokument)

Figure 2.1: Included components of the KT-7900D package.
3. Opsætning
3.1 Montering af transceiveren
Select a stable and secure location for the transceiver, ensuring adequate ventilation around the unit. Use the provided radio bracket and mounting hardware to secure the unit. Ensure the location allows for easy access to controls and connections.

Figur 3.1: Side view of the KT-7900D, highlighting the heat sink for proper ventilation.
3.2 Strømtilslutning
Connect the DC power cable to the power input port on the rear of the transceiver. Ensure the polarity is correct (red to positive, black to negative). Connect the other end of the DC cable to a 13.8V DC power source, such as a vehicle's cigarette lighter socket or a regulated power supply. The cable includes a cigarette plug connector for convenience.
3.3 Antenneforbindelse
Connect a suitable antenna (not included) to the antenna connector on the rear of the transceiver. Use a coaxial cable with a compatible connector (typically SO-239 for the radio side). Ensure the antenna is properly tuned for the operating frequencies to prevent damage to the radio.

Figur 3.2: Bagside view of the KT-7900D, showing the cooling fan and antenna port.
3.4 Mikrofonforbindelse
Plug the speaker microphone cable into the microphone port on the front of the transceiver. Ensure it clicks securely into place.

Figure 3.3: KT-7900D with the speaker microphone connected.
4. Betjening af transceiveren
4.1 Tænd/sluk
To power on the transceiver, rotate the volume knob clockwise until you hear a click and the display illuminates. To power off, rotate the volume knob counter-clockwise until it clicks off.

Figure 4.1: Front panel of the KT-7900D with display and controls.
4.2 Lydstyrkejustering
Adjust the audio output level by rotating the volume knob (typically the left-most knob on the front panel).
4.3 Valg af frekvens/kanal
Use the main tuning knob (right-most knob) to change frequencies or navigate through memory channels. The V/M button switches between VFO (Variable Frequency Oscillator) mode for direct frequency input and Memory mode for stored channels.
4.4 Sending (PTT)
To transmit, press and hold the Push-To-Talk (PTT) button on the side of the speaker microphone. Speak clearly into the microphone. Release the PTT button to receive.
4.5 Keypad Functions (Speaker Microphone)
The speaker microphone features a DTMF keypad for various functions:
- MENU: Få adgang til radioens menusystem.
- OP/NED-pile: Naviger i menupunkter eller juster indstillinger.
- EXIT/AB: Exit menu or switch between A/B VFOs.
- */SCAN: Initiate scanning.
- #/LOCK: Lock/unlock the keypad.
- Numeriske taster (0-9): Direct frequency input, DTMF tones, or menu selection.

Figure 4.2: Speaker Microphone Keypad.
4.6 avancerede funktioner
Refer to the on-screen menu for advanced functions such as FM Radio, PTT ID, DTMF signaling, Remote Stun/Kill, Repeater settings, Alarm, Monitor, and High/Low Power settings. Detailed explanations for each function are typically found within the radio's internal menu system.
5. Vedligeholdelse
5.1 Rengøring
Wipe the transceiver with a soft, dry cloth. Do not use harsh chemicals or abrasive cleaners. For stubborn dirt, a slightly damp en klud kan bruges, efterfulgt af en tør klud.
5.2 Miljøhensyn
Avoid exposing the radio to extreme temperatures, direct sunlight for prolonged periods, or excessive moisture. Ensure proper ventilation, especially during extended transmission, as the unit can generate heat. The built-in fan assists in cooling.
5.3 Firmware and Programming
Periodically check for firmware updates from the manufacturer's official website. Use the provided programming cable and compatible software (e.g., CHIRP or QYT's proprietary software) to update firmware or customize channel settings. Always back up your radio's configuration before making changes.
6. Fejlfinding
| Problem | Mulig årsag | Løsning |
|---|---|---|
| Radioen tænder ikke. | No power, incorrect power connection, blown fuse. | Check power cable connection and polarity. Verify power source. Check fuse in the DC cable. |
| Ingen lyd fra højttaleren. | Volume too low, squelch set too high, speaker microphone not connected. | Increase volume. Adjust squelch level. Ensure speaker microphone is fully plugged in. |
| Kan ikke sende eller modtage. | Antenna not connected, incorrect frequency/channel, high SWR. | Ensure antenna is securely connected. Verify correct frequency/channel. Check antenna SWR. |
| Programming cable not recognized by PC. | Incorrect or outdated driver, cable issue. | Install the correct FTDI driver for your operating system. Try a different USB port. Ensure the cable is fully inserted into the radio's programming port. |
| Low output power on certain bands. | Antenna mismatch, radio fault. | Verify antenna tuning for all operating bands. If issue persists, contact support. |
7. Specifikationer
| Feature | Detalje |
|---|---|
| Mærke | QYT |
| Model | KT-7900D |
| Frekvensområde | VHF: 136-174MHz, 220-270MHz; UHF: 350-390MHz, 400-480MHz |
| Udgangseffekt | VHF: 25W, UHF: 20W |
| Frekvensstabilitet | ±2.5 ppm |
| Hukommelseskanaler | 200 |
| Forsyning Voltage | 13.8V DC ± 15% |
| Squelch opsætning | CARRIER/CTCSS/DCS/5 Tone/2 Tone/DTMF |
| Driftstemperatur | -5°F til +140°F (-20°C til +60°C) |
| Dimensioner (L*B*H) | 12.5 x 9.9 x 4.5 cm (4.92 x 3.89 x 1.77 tommer) |
| Varens vægt | 0.45 kilo (15.8 ounce) |
| Antal kanaler | 200 |
| Maksimal talerækkevidde | 20 Kilometer (theoretical) |
| Vandmodstandsniveau | Ikke vandafvisende |
8. Garanti og support
For warranty information and technical support, please refer to the documentation provided with your purchase or contact the QYT customer service directly. Keep your proof of purchase for warranty claims.
For software and driver downloads, including the programming software, please visit the official QYT website or contact their support team for the most up-to-date resources.