WOW! Thanks for all the input guys. Let me answer as much as I can and then I'll run the dmesg again.
I have a Pi Zero W powered by a 5.1 VDC 3A power supply with a cable that has a pushbutton switch to make rebooting easy. The power supply appears to be as advertised and is not causing any offensive noise as testing from a Palmpad at the same time as the issue appeared worked fine. As petera pointed out, the extra ampacity won't hurt the pi and may be beneficial in running the CM-19A. Photos attached.
I have the OTG hub plugged in and, yes, the dmesg I posted shows the mouse and keyboard as I needed them to enter the commands as I haven't yet done what's needed to get into the Pi via the web. Right now going to the Pi's IP puts me on the HA-Bridge page. When not in use the KB & mouse are unplugged. I'll eliminate the OTG hub and just use an adapter once I've set up web access or can do it now for testing. Coincidentally, I ordered the same OTG hub w/Ethernet in the ZDnet article yesterday and Amazon will deliver it tomorrow (Ya gotta love free Sunday delivery!)
The CM-19A transmits to an RR501 plugged into an early version XTBR in the same room (10' away) and there is an XTB-IIR in the house so I have no apparent signal issues. As I mentioned above, transmitting from a Palmpad worked.
Since I modified the Interfaces file with the info I mentioned yesterday, the Pi has had no WiFi drops so I'm hoping that's solved. Also, since I rebooted to solve the signal issue it has not reappeared.
Regarding what's loaded, I've kept it simple as I only want to use this as an Alexa hub. After installing Raspbian Stretch (full version) and letting it go through updating, I ran Tuice's hub installer which works perfectly. The only other thing I've done is the change to the Interfaces file for the WiFi issue. I don't need anything else as the Stargate does all the heavy lifting. In fact, the hub is just used to send ON/OFF to unit codes on a vacant house code which the Stargate uses to trigger macros.
At is point, my thinking is that the PiZW is sending to the CM-19A because the light flickered and the RR501 is OK as it worked with the Palmpad. My IR temperature gun shows the power supply exterior at 79F and the Pi's heatsink at 85F so overheating is an unlikely culprit.
That leaves a few possibilities; either the PiZW was sending corrupt data or the CM-19A had a problem solved by a reboot. I wish I would have rebooted just the CM-19A first rather than rebooting both. Sitting between the two is the OTG hub so maybe that's the culprit. If/when it happens again I'll be able to experiment further.