ESP32-Based Active HF Frequency Tracker for Kenwood TS-520

Overview

This system is an active high-frequency (HF) tracking and digital display upgrade designed for legacy radio equipment. It samples the internal high-frequency oscillator signals from the radio, amplifies them through a custom discrete transistor stage to match modern logic thresholds, and processes the frequencies using an ESP32 microcontroller to compute and display the real-time operating frequency of the radio.

Key features

• ESP32 uses hardware timers / dual-core throughput to sample HF signals, apply band-dependent offsets, and drive UI logic.
• Custom discrete transistor amplifier: high bandwidth and input impedance to reach reliable 3.3 V logic without loading or detuning the radio’s sensitive oscillator nodes.
• Firmware frequency engine adds/subtracts measured oscillator components according to the transceiver’s active band configuration.

PCB layout

The discrete amplifier sits next to the input connectors so unamplified HF runs stay extremely short. Digital traces to the ESP32 and display headers are kept away from sensitive analog inputs to reduce switching noise injection. A solid bottom ground plane lowers inductance, provides a clean HF return, and shields analog nodes from digital hash.