I know most folks in Dallas can't receive it anyway, but it looks like KPFW/18's transmitter is frying. Shortly after 5PM it started shutting down, then starting back up for a short while, then shutting down again. The intervals between restarts are getting longer too.
Looks like it gave up the ghost completely about 5:30 Wed. morning.
And it looks like they turned the transmitter back on very early Thurs. morning, but I can't get a lock. I wonder if the engineer who "fixed" it is the same one who works on KVFW's equipment?
Finally got it working again about 11:30 this morning.
Oops - not quite. Died again about 4:30.
Popped back on very briefly very early Sunday AM, then they were gone again.
I don't understand what's going on with KPFW. When it's working, I actually see a slight drop
in signal strength. It's almost as if they're trying to broadcast from two locations (which doesn't work with ATSC 1.0), and I only get them when one transmitter shuts off! Surely that's not what's happening?
OK, this time for sure? Looks like they fixed it - again - about 3:15 PM today, 9/27. Holding so far....
I think I figured it out. There was indeed a second transmitter involved; believe it or not, it was KTVT on RF 19! Figured it out by comparing 10-day signal strength graphs for RF 18, 19, and 20.
On the afternoon of 9/20, when I posted Edit 2 above, KTVT's signal strength went up from its usual 90-something to a full 100. At the exact same time, the signal strength on RF 18 appeared to jump, but I couldn't lock anything. I had assumed that KPFW had turned on their transmitter but had goofed it up somehow. Apparently, though, that was just noise from KTVT's signal overloading my preamp or something.
On 9/22, KTVT temporarily went back to normal, and KPFW started working again. Then KTVT went back up to 100 and I lost KPFW again (edits 3 and 4 above). And today, KTVT went back to normal again and sure enough, KPFW came back again.
The clincher was the signal graph for RF 20. The signal strength has been roughly constant but the signal quality drops at exactly the same times that KTVT's signal went to 100.
Now I wish I knew what's been going on with KTVT and whether it has stabilized for good.