last week I made some succesful tests with the U3S on 475 kHz and 137 kHz (WSPR2 and WSPR15 in mixed mode!). Now I'm trying to go down to 8.27 kHz and below. Thats why I designed a a 5 pole Chebysheff filter (fg abt 10 kHz) for your LPF switch kit. The filter works fine.
My probelm is: The U3S does not produce an 8 kHz signal. The minimal frequency I could achieve was 28 kHz. Now I assume that there is possibly the same situation as described above.
Is there any chance to change the internal dividers to go down to 8 kHz possibly also to 4 kHz? Or ist the only way to use an additional divider with the need of changing the WSPR firmware to do this?
My goal is to transmit on 8.27 kHz (possibly also down to 4 kHz or between) with WSPR2 and WSPR15 mode.