Low signal strength only when filters installed

[bkenobi]

I'm going to mark this as closed, but the reason is very peculiar.  The issue disappeared even though I did nothing.  I randomly decided to plug the meter into the outlet yesterday since it was sitting there anyway and, what do you know, it worked!  I was getting a signal strength of 9.55 from the XTB-IIR.  I checked the other circuit that was an issue and I have 9.xx there too.  Very strange!

The only thing that changed that I can think of is that the arduino that was in my attic fan controller was swapped for a different unit (same power cube) and an incandescent bulb burned out and was replaced.  Neither of these should make any difference, so it appears that it's better for no reason.

I guess I'll move on, but I wish I knew the cause.

[Noam]

... and an incandescent bulb burned out and was replaced. ...
I guess I'll move on, but I wish I knew the cause.

I've known some incandescent bulbs to start "buzzing" before they burned out (very rare, but I've had it happen to me).
I suppose the buzzing could have put noise on the line.