440 MHz on Dhiru's Notebookhttps://rfcorner.in/tags/440-mhz/Recent content in 440 MHz on Dhiru's NotebookHugoenFri, 03 Jul 2026 00:00:00 +0000WSPR Beacon Ideas for UHFhttps://rfcorner.in/posts/uhf-wspr-beacon-ideas/Fri, 03 Jul 2026 00:00:00 +0000https://rfcorner.in/posts/uhf-wspr-beacon-ideas/<p>This is an early design sketch of a UHF (70cm - 440 MHz) WSPR beacon.</p> <p>This design comes from Ismo (OH2FTG).</p> <h2 id="key-points">Key Points</h2> <ul> <li> <p>10 MHz OCXO TCXO powering the Si5351 module instead of the usual 25 or 26 MHz 0.5 ppm TCXO.</p> </li> <li> <p>Si5351 generates 217 MHz output, which we double to ~434Mhz using the <a href="https://techlib.com/files/diodedbl.pdf">https://techlib.com/files/diodedbl.pdf</a> technique.</p> </li> <li> <p>Use 440 MHz SAW filter at the output (from LCSC)</p> </li> <li> <p>Modulation is continuous phase 4-FSK, with 1.4648 Hz tone separation.</p>