Planning to build the uSDX-RX Arduino Nano direct conversion receiver that's been making rounds lately. The design uses digital signal processing for AM, FM, SSB and CW reception across HF with surprisingly good performance.

Two questions for those who've built this:

• Best source for the 74HC4053 analog switches? Seems like the critical component for I/Q mixing
• Anyone tried substituting the SI5351A module with a bare chip implementation for better phase noise?

Also seeing conflicting info about whether the SRA-1 diode ring mixer version performs better than the 4053 switching approach. Circuit is simple enough for breadboard construction but want to get it right the first time.

Built mine last month - stick with the 4053 CMOS switches, they work great. Got mine from Digikey, avoid the cheap Chinese clones as they have higher Ron resistance. The SI5351 module is fine, bare chip won't make much difference at HF.

For better performance, add a 2N5109 RF preamp stage ahead of the mixer. The design is quite sensitive but you can improve it further with 10-15dB of low-noise gain on 20/40m.

I've built both versions. The SRA-1 mixer has slightly better IMD performance but requires careful transformer winding. For first build, go with the 4053 version - much easier to troubleshoot and still excellent results for QRP work.