Brian: I have unplugged various likely culprits with questionable success. My only phase coupling is a .1 mfd capacitor currently off line as it doesn't appear to have an effect. I swapped breakers to keep all (I think) modules on one phase so this shouldn't be a problem.
Dave W: I am thinking of the ability of the XPCR to boost the signal. My home is under 2000 SF but I do have a lot of electronics, more than a few CFLs, a new steam washer and dryer with digital controls,, the usual microwave dishwasher etc all with digital controls etc etc. The biggest problem seems to be the AHP/CM15a doesn't always work. I have 2 APC UPS units that may be contributing to the problem. I ordered 2 XPF filters to isolate them from the house. I'm also considering the XPNR small filter if I can pin down the offending appliances.
Thanks much for the replys.