Weird AMC3 problem with big dish.

[wejones]

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.

[rainman]

to see if it's the lnb Bill you could try using a heat source to warm up the lnb when you loose signal to see if it comes back that way you will know if it's the lnb or connector.

[wejones]

to see if it's the lnb Bill you could try using a heat source to warm up the lnb when you loose signal to see if it comes back that way you will know if it's the lnb or connector.

First, when I said IA8 above, I meant AMC9.

Thanks. Until it warms up a bit, I can't really get to the lnb to warm it. :-)
Yesterday, I seemed to have lost PBS even later in the morning/afternoon. I did switch the connector yesterday, actually put a new one on Ku, and put the Ku connector on C-band. At first it didn't seem to do anything. However I later moved the dish to IA6 C-band, and watched a channel there for a couple hours, then suddenly lost that channel. This morning, I tried IA6-Ku, and was getting nearly full scale on one of the NBC news channels, then went to AMC3, and got nothing. Usually, I peak the dish on AMC3 using the Dr Scott channel on C-band, so I switched to analog..... NOTHING... looked like the Drake receiver was completely dead on C-band, even though it was getting noise on Ku, which is normal. Weird. So I went downstairs, pulled off the coax, and checked the voltage out of the C-band connector, and it was only about 16.5V, which is a bit low. Then I remembered that I think the voltage out at the dish yesterday was only about 13V!! That should have thrown up a red flag right there, since this was powered by the analog receiver, except that for some reason my mind was thinking FTA receiver and I was thinking I must be on the 13V polarity, forgetting which receiver I was using.
Anyway, put the coax back on the Splitter... still nothing on C-band. So I bypassed the splitter, went straight to the Drake. C-band analog came back to life!?!?! Dr Scott in all his past life. Re-connected the splitter, expecting the signal to go away again, however he was still there. ?!?!? Also had PBS back on Ku DVB, although the signal strength was still a bit low. Ran the Ku coax directly to my Ultra, instead of going through the splitter and DiSEqC Switch. Signal strength came up as expected since I wasn't splitting.
Anyway, more confused than ever, but starting to think it's a low voltage to lnb problem, and I'm right on the edge.

[wejones]

Some progress, I THINK. I went back down to play with this some more, turned on the video from the Drake analog receiver, and C-band was DEAD again!?!?! I decided that it must be that my Drake was dying, so I hooked up the C-band coax to my Monty 50/55. No signal there either?!?!? I was still controlling polarity with the Drake, so I pulled the polarity wires off the Drake and put them on the Monty.... Still Nothing. Now, I was convinced that my C-band LNB was dead. So I went outside. Hooked up my Channel Master meter to the C-band LNB, powering it with the meter, but going through the female-female in line connector. Hardly any signal, and what signal there was, was jumping on and off rapidly. Disconnected again, and connected the lnb to the meter again, this time bypassing the in line connector. Now, there was good signal!! Re-connected via another connector. Still had signal. Went back inside, and had Dr Scott coming out of my Monty!! :-)

Anyway, this is weird. Apparently the darn in line connector has a intermittant discontinuity. Never heard of such a thing. This is one of the types that screws down as a ground block. Anyway, I think I'm back in business. I just hope that the Drake wasn't hurt, as I haven't reconnected it yet, but I suspect it was just that the connector was open, not shorted.
Also, this connector was originally connected to the Ku line, but I switched it to the C-band line during my testing.