Mike
I built a Progressive Receiver (W7ZOI) last year with si5351 and stayed with the original dual conversion frequency mixing scheme, a first (tuneable) IF of 3.5-4MHz, second IF 9MHz.? I used all 3 si5351 clocks, first for VFO, second for heterodyne osc, 3rd for BFO.? It was riddled with birdies, unusable.? First I built a crystal BFO and buffer, eliminating the need to use the third si5351 clock.? Made almost no discernible difference.? Finally I ditched the dual conversion scheme and reconfigured it into a single conversion superhet with high side VFO.? Problem fixed.? ?Well almost.? There are still a few odd birdies, but just a handful, all are well below the usual received signals.? I now use this receiver frequently on 160 to 40m and it works well.? has some gain distribution issues but that's a different problem.??
I suspect the clocks are rich in harmonics and that by placing f-VFO above f-IF they no longer bother me.?
My rx has tight receive BPFs.? It could be shielded better.
I also started scratch building a uBitx and got it receiving, kind of, not really, lost interest for another build, will come back to it one day.?
Regards? Paul VK3HN.??
VK3HN