Thanks pachinko, those were some tricky things to look out for, who would ever suspect the electric blanket, lol.
With my HD observations, I check the reception on other channels to compare with the channel having problems. If the main channel and all it's sub channels are down, but the others are up, even the weaker ones, then I assume it's just the one station in question having problems, and not my antenna setup. I check it with the TV tuner and the DVR tuner to compare. Usually it's just one channel (and associated sub channels) having a problem at any given point of time......but different channels having problems at various times. I use a Yagi with no power amp, coax split 3 ways no more than 40 total feet of coax, and get good signal strength for most channels. Right now I'm getting 86% for Fox 17, around 70% for 19 and 23, and KCCI 8 about the same, around 55% for 5 and 13, and the weak ones are 25% for PBS 11, and around 15% for 39 (low power station from Newton, dropouts to be expected).
KCCI went down last Friday morning and trashed the end of Drew Car Week on Price is Right, right at the critical point in the show when they played for the 100K car they went down for about 10 minutes. The people with Cable or Satellite may not see as many problems, if the problem is with the transmitter, as I think they tap off the signal for Cab/Sat before the transmitter section....which could be the problem. I suspect they probably don't care that much about the OTA viewers anyway, and give OTA a lower priority since OTA is a small % of total viewership anyway, and not really a prime target for the advertising market either.