In the PSK-30, Dave uses an intermediate frequency of 4.000MHz and a local oscillator employing a 6.144MHz crystal. The oscillator is pulled into place to match the PSK31 center of the 30m band.
In order to get the LO down to our QRSS/WSPR range, one may consider just pulling the oscillator further. However, this possibly compromises stability.
My suggestion here is to pen down a 6.144MHz standard crystal to 6.1387MHz, which is very easily done.
Information about penning down a crystal, you will find here on this blog.
Please not, one needs to make sure that the BFO is set for USB!
