A new tool is emerging for operators using hardware Robust Packet modems — a way to bring real keyboard-to-keyboard chat to HF using the same RPR technology behind Winlink and APRS.
If you’re running a LiNK500, LiNK500MP, Teensy TNC, or SCS Tracker, there’s a new way to experiment with keyboard-to-keyboard communication over Robust Packet Radio (RPR) — and we’re inviting you to join the testing group.
The software is called Robust Chat, and it is currently in active development and beta testing. It’s designed to bring reliable, two-way HF text communication to the RPR ecosystem — a modern alternative to legacy AX.25 packet. The goal is simple: create a practical, RPR-based, low-power, off-grid messaging platform that works anywhere HF can reach, continually evolving through real-world field testing and operator feedback.
We’re currently testing real-world performance across different bands, distances, and hardware combinations to understand how the protocol behaves under QSB, fading, and noise. Each test helps refine link behavior, timing, and overall reliability.
If you’re using a hardware RPR modem — LiNK500, LiNK500MP, SCS Tracker, or Teensy TNC — your participation would be extremely valuable. The more diverse the equipment and conditions, the better the data we collect.
The LiNK500 and LiNK500MP modems are available from DIY599, designed by DL4KA. You can learn more or purchase one at https://diy599.net.
We’ve set up a Telegram group for coordination and discussion:
LiNK500 & RPR Chat APP
Ham radio operators interested in joining the test network can message to request access. Once inside, you’ll receive testing instructions, current frequencies, and setup details for your modem and software.
Together, we’re building a reliable, field-ready RPR chat system — one more tool for resilient, off-grid communication.
About Robust Chat
Robust Chat is a free, lightweight messaging application designed specifically for hardware RPR modems such as the LiNK500, LiNK500MP, and Teensy TNC. It provides real-time keyboard-to-keyboard communication over Robust Packet Radio (RPR), offering operators a dependable way to exchange messages directly over HF using proven, narrowband technology.
The software is open-source and currently in active beta development, with updates released regularly. It’s designed for operators who prefer a simple, hardware-based, low-power solution for text communication that works entirely independent of Internet infrastructure.
Robust Chat is available for Windows, with future platform support planned. It continues to evolve through field testing and community feedback from RPR modem users worldwide.
You can learn more or download the current release from:
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Julian, OH8STN
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