Qyt Kt-7900d Service Manual May 2026

The Complete Guide to the QYT KT-7900D Service Manual

The QYT KT-7900D is a popular, high-power Mini Mobile Amateur Radio. Known for its compact size (often called a "midget mobile") and wide frequency coverage, it is a favorite for off-roading, emergency comms, and SHTF prepping.

4.1 PLL Reference Frequency Adjustment

• Set radio to 145.000 MHz, high power, no modulation.
• Connect frequency counter to TP1 (VCO test point near RDA1846).
• Adjust trimmer capacitor TC1 until counter reads 145.000 MHz ± 50 Hz.

FCC Internal Photos: View high-resolution circuit board layouts and component placement via the FCC ID 2AV62KT-7900D database. qyt kt-7900d service manual

• RX Path: Antenna → LPF → RF Bandpass Filters (per band) → LNA → 1st Mixer (45.05 MHz IF) → Crystal Filter → 2nd Mixer (455 kHz) → Ceramic Filter → FM Demodulator → Audio Amp.
• TX Path: Microphone → Audio Preamp → VCO Modulation → RF Power Amplifier (RD15HVF1 / RD70HVF1 depending on band) → LPF → Antenna.
• PLL: Based on RDA1846 or similar SDR-on-chip, controlled by STM32 MCU.