Over the last few days, I've observed a strange thing on my 10' dish. I watch a lot of PBS, and usually keep all my dishes aimed at AMC3 when not using them elsewhere, however we got a 16" of VERY HEAVY snow last several days ago, so I had parked my dish down to the west (didn't help... the thing still filled up with snow).
After the storm, I scraped the snow off, and drove the dish back to AMC3, however I wasn't able to lock on AMC3, just getting the slightest indication of the thing trying to lock, but it wouldn't hold. I was tuned to the 12180/30000 transponder, so thinking that the dish was a bit out of sync, and that I might be on a side-lobe, so I ran the motor east, until I got a strong lock, however I was instead locked on the 12180/30000 data transponder on IA8. Full 90%/90% signal. Moved the dish back west, past the partial lock position, but nothing. The original position where it was going in and out of lock was the peak. So I assumed that the weight of the snow had pulled the dish down, and got the thing out of alignment. However, I went out and tried the regular push up/pull down thing to find out if this was the case, however I found that pushing up and pulling down BOTH reduced the signal. So the sat was centered both up and down, and along the ARC... and yet I had lost my PBS channels. This was in the morning. I was very confused, so I gave up for a while, and switched to one of my small dishes to watch PBS for a while. But I came back to my big dish a couple hours later. PBS was back, almost as strong as ever!?!?! I hadn't changed ANYTHING. Went from no lock to locked with a fairly strong signal. I thought that this was strange, but figured that it must have been something related to the weight of the snow, and that by my pushing up and pulling down that I have eventually straightened the thing out.
HOWEVER, the next day, in the morning, I tried again to watch PBS, again, I hadn't changed ANYTHING. No PBS!?!?! I waited for a couple hours, changing nothing. PBS was back. Again, it wasn't that PBS was gone, as I could still see it on my 3' dishes. Anyway, it seems like the most probable thing is that my LNB has begun to be temperature sensitive, and is losing sensitivity when it is cold in the morning, but get's it's sensitivity back later in the morning when it warms up. It's also possible that it is due to the fact that I have the coax cut, and going through an inline coupler so that I can "easily" connect a meter. And I don't have this connection weatherproofed. I used to have it wrapped with that black tar stuff, but in the winter that stuff is almost impossible to get off when I want to put a meter in there, so the last time I connected a meter, I just wrapped a plastic bag around the connection instead of wrapping it with tar. So perhaps water has gotten into the coax or the connector, and is freezing when cold or something. Perhaps I should try replacing the inline connector, and/or cutting off a couple feet of coax, in case water got in the coax.
I can't think of any other reason why I would lose signal on AMC3 like that only in the morning, and it still doesn't make sense that I'm getting basically full scale signals on IA8, but not on AMC3, even though it's the same freq/SR. Anyway, it's a bit confusing. I have a couple backup Ku lnbs that I haven't used for a while, so when the snow melts enough for me to get the tractor up to the dish so that I can reach the feedhorn, perhaps I'll switch LNBs.