Also had a 100 set up using Spectran in 0.042 Hz mode running on same audio.
Sigs looked much the same.

Rx antenna was just 1 foot of wire without preamp to try to get some noise
into your basically very strong sig.  Rx was 756PRO in CW using 100 Hz BW.
No audible sig.

Next time, I'll set up the 100 in Jason slow mode and run it in parallel
with the 233 in normal mode to see if any difference.

Walter G3JKV.