On May 12, 2025, at 1:37?PM, John Bennett via groups.io <jkb@...> wrote:

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In the spirit of posting efforts currently underway, I have been working on a new RF board and associated driver software. In a nutshell, the new board uses the Skyworks SI5340 instead of the SI5351. This change addresses several issues. The SI5340 offers rock solid performance from 100 KHz to 250 MHz with LVCMOS outputs (employed by the prototype RF board), dramatically reduced phase noise and jitter, much improved clock symmetry (upon which the performance of Tayloe mixers depends), and much simpler application-level control software (no mucking about with the PLL, Multisynth, or phase at the application level). The new RF board replaces the 5351 with the 5340, and restores true split operation (the SI5340 has four outputs, three of which are used for RX, TX, and CWTx). The most challenging part of the software was the algorithm for setting output frequency, that is, given a desired frequency, find near-optimal numerator and denominator values for the various dividers used within the SI5340. My software employs a mediant-based algorithm attributed (incorrectly) to Farey, and efficiently produces results comparable to those produced by ClockBuilder Pro (the stand-alone program for configuring Skyworks parts). Current status:

1) Driver and driver example code complete and tested with main board and SI5340 EVB

2) T41 software (forked from V66.9) patched to ifdef choice of SI5340 or SI5351 RF Board compiling and in test

3) New RF board hardware under construction (PCBs back from China; parts on hand)

For the curious, prototype schematic and board pic are attached.

73,

John Bennett

AE0AM

<AE0AM_RF_Bd.jpg>

<AE0AM_T41_RF_Prototype.pdf>