I usually narrow down the rx bandwidth to 600 Hz when the signals are marginal. I didn't narrow the filter is this case.

Okay here are a couple screenshots. This time I was hearing the other station better. The Mine text box was -09 meaning I had a 5 dB advantage on receive. Usually the opposite.

Joe, I just did a ping test with you on 20 meters. You're hearing me 3 dB better than I'm hearing you. Of course this is just one test. But it confirms my suspicion that two urban stations running similar power will have comparable received signal levels.

Thanks Gary! I was there at the rig watching your multiple connections & tests. You verified what I already knew. I also ran some tests on JS8 & found similar results. Somehow I was under the impression that I had good reception on HF. A local HRO store has horrible power line noise being a block away from a power line transformer. Yet listening to a west coast WebSDR site (KFS) about 300+ miles north of me is very discouraging. When I think 20 meters is dead, the site is showing numerous CW signals missing on my waterfall. I can copy the strongest ones from my QTH. I also used to always get better reception on FT8 than the connected stations. Perhaps that's no longer true. I need to try a few FT8 contacts again to verify. My reasoning is that most of the stations out there are also in urban areas & should also be equally compromised on receive. But that's not always the case.

My sound card is built into my FTDX10. So there isn't much i can do to improve it. I use a high quality USB cable back to my PC with toroids on each end. Also run 600 Hz filter and VU meter at mid scale.

I'd like to hear about this also. So far I haven't seen transmission bursts > 6 seconds, but won't say so with certainty. My reasons are different from yours. I'd like to know how much power I can safely drive my radio. It's rated at 50% with full carrier modes. With VarAC the full carrier bursts are brief so I can go above the 50% of the full power recommendation by Yaesu. Simply unsure how much higher. My educated guess for your EMF assessment is it's well under 50% but highly variable. Don't depend my guess...