Circuit: DDX-Commercial-7
Antenna: Small jumper cable attached
10m: 36 dB on WSJT-X audio meter, on quiet and also with nearby beacon on !!!
12m: 36 dB on audio meter, on quiet and also with nearby beacon on !!!
15m: 46 dB on audio meter on quiet, 65 dB with nearby beacon on - OK
20m: 44 dB on quiet, 65 dB with beacon on - OK
40m: 40 dB on quiet, 60 dB with beacon on - OK
Next:
Same jumper antenna -> 20 dB LNA (Zeenko BM) -> 10 dB ATTN -> Same RX circuit as before
10m: 47 dB on audio meter on quiet, 63 dB with beacon on. SnR is much improved (checked on WSJT-X spectrum and FT8 decodes).
20m: 55 dB on quiet - OK, frontend running hot?
40m: 54 dB on quiet - OK, frontend running hot?
Finding 1: 10 dB gain works better than 20 dB gain on 10m. Too much gain can be problematic!
With actual 5m EFHW antenna attached: Audio meter is near 60 dB on 10m - great!
Conclusion: We need to fix the RF gain problem on 12m and 10m bands.
With Zeenko BM LNA added:
The "waterfall spectrum" display is pretty clean!
