Signal weakens as day gets hotter

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thatuldo

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Jul 12, 2009
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birmingham
Hi, New to forum and hoping someone has had a similar experience. I have had DTV for 15 years but moved two years ago this month so that is how old this installation is. I have a MPEG4 KU/KA Band Slim Line Dish feeding a Zinwell WB68 6X8 multiswitch. The coax run from the LNB to the multiswitch is 16 feet. In the house is an HD DVR and a regular receiver neither of which ever cause a problem. The third receiver is in my shop building 85 feet behind my house. The coax run from the multiswitch to this receiver is 102 feet. For two years I had no problems with this location using an old RCA receiver, then about 6 weeks ago I started getting some pixilated channels occasionally. It got worse until about two weeks ago it was doing it every day. The strange thing is it is heat related. I am in Birmingham, Alabama and it has been getting in the mid to high 90's lately. At night or even after it rains and cools things off I get all the channels, but by 1 or 2 PM most of the channels are blank or pixilated. The local channels are never a problem. I thought it might be the coax from the multiswitch (buried) so I bought a new RG6 cable and swapped it out with no improvement. After several conversations with DTV tech support they thought it might be my old receiver and sent me two new ones for free through their Legacy program. I tried both of them with no sucess. I then bought an inline signal booster from Radio Shack and tried it. I took that back for a refund the next day and called DTV for a service call. After waiting 7 days for the tech to come, here is what he did. Replaced the LNB and multiswitch. Replaced all four coax cables from the LNB to the multiswitch and replaced the cable from the multiswitch to the receiver with new duplex RG6 cable and of course re-aimed the dish. None of this has helped as I still have all the channels when it’s cool and loose most of them when it’s hot. Obstructions are not a problem as my dish looks at open sky. I verified this on the dishpointer website and the DTV tech concurred. Again, no problem for two years and now this. Anyone ever heard of anything like this before?
 
Can you tell if it is really heat related or possibly where the sun is in the sky?
In other words, it could be the time of day with the sun interfering with the signal from the sats.
When the sun is directly in line with the sats (behind) and your location, it can cause problems.
 
Its got to be the heat for two reasons. It worked fine for two years before becoming a problem and the channels don't "return" until after dark when things cool down. If it was the position of the sun it would be relatively short lived, right? If this was a new install I would think it was just too far of a run for RG6, but again it was fine for two years and everything has been replaced now with new.
 
Yes the multiswitch was replaced along with everything else I listed in my original post and it is located inside. As to the signal strengths they are irratic. I will have to copy them down tommorrow but they vary a lot from one minute to the next. The transponders on sat 101 can be all in the mid to high 90's one minute and then drop to a range of 60 to 80 or lower. At the worse, I have seen 1/3 to 1/2 of them at 0 and the rest from the 30's on up. As to the ground block, I guess you mean the multiswitch ground. It is grounded to my main residence power mast where my powere meter is. It is a 2" galvanized pipe and the ground wire to the multiswitch is a heavy gauge solid copper wire. Looks new, so the tech the other day probaby replaced it.
 
Strange problem and it looks like everything but the dish itself was replaced, if I read your OP correctly.

It is technically possible that the dish itself is warped- and the heat could theoretically cause the warpage to increase (expansion) to the point where the signal would get screwed up. It's also possible that the mast is slightly put of plumb, and heat expansion could make that worse too.

I've never seen it happen on a DTV or DN dish because the signals are pretty strong - but it is possible.

I'd be tempted to try cooling off the dish (back side with a hose) when it is acting up just to verify - since just about everything else has been tried.
 
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Roger the strange problem. Yes everything but the dish was replaced. I build custom furniture full time and as a one man shop the TV is my company all day so this is really a pain. I failed to mention that the tech from DTV was a little skeptical of the original mast installation. It had a little movement in it when forced so he replaced it as well. I watched him and he was careful when he plumbed it, but he used a 6" magnetic level and they have their limitations due to their length. I will check it with a 2 foot level. Also the tip about cooling the dish off with a hose is good, I will try that. It rained here yesterday cooling everything down, and while all the channels weren't perfect, they were vastly improved over what they usually are on a hot afternoon. Again, thanks for the help guys.
 
Another wierd thought or 2 for a wierd problem - check the coax wherever it takes a corner or a somewhat sharp turn. It could have been pulled a little tight and the internal conductor could be partially separating as the copper core heats up. If that's the case, wiggling the spot would cause your signals to jump all over the place. That would also happen if the coax is not properly seated into the connector - the white inner core needs to be flush with the flange when viewed from inside the connector.
 
Was gone most of the day and didn’t get to record readings this morning when it was cool, but here are the values this afternoon. I recorded them three times over about a ten minute period and you can see the erratic numbers on some of the Sat 101 transponders. Sat 110 stays dead steady as does Sat 119 except for transponder 27. I checked the air temp with a Fluke multimeter when I took these readings and it was 87.6 degrees on the roof next to the dish. The surface temp of the dish itself was 99.4 so it was not that hot. The day had already started cooling down some as it was hotter earlier in the day. At the time I took these readings most of the channels were blank or pixilated as usual. I noticed that the odd numbered transponders are the ones with the fluctuating signal strengths so I downloaded the Transponder Map on this website. I then noted all of the channels I have problems with and they all map to an odd numbered transponder. I never have a problem with any local channels and according to the map, they all come through on Sat 101 transponder #28 which is always at 100%. So what gives with only the odd numbered transponders having a problem? By the way, the only other transponder with goofy numbers is #27on Sat 119 which is also an odd number. I bet this is a significant bit of info and one of you geniuses is going to tell me what’s going on here….right?

Sat 101 at 4:35 P.M.

0 96 0 0 81 97 75 96
79 97 77 0 75 98 0 97
78 100 78 0 69 97 76 97
79 96 77 100 75 97 73 97

Sat 110 at 4:37 P.M

- - - - - - - 94
- 94 - 95 - - - -
- - - - - - - -
- - - - - - - -

Sat 119 at 4:38 P.M.

- - - - - - - -
- - - - - - - -
- - - - - 98 0 96
53 98 0 98 0 98 0 98

Sat 101 at 4:40 P.M.

75 96 0 21 75 97 77 96
84 97 96 0 90 98 90 97
96 100 96 0 91 97 96 97
96 96 95 100 95 97 95 97

Sat 110 at 4:42 P.M.

- - - - - - - 94
- 95 - 95 - - - -
- - - - - - - -
- - - - - - - -

Sat 119 at 4:38 P.M.

- - - - - - - -
- - - - - - - -
- - - - - 98 0 96
55 98 89 98 0 98 0 98

Sat 101 at 4:35 P.M.

97 96 95 19 96 97 95 96
96 97 96 0 96 98 96 97
96 100 96 0 96 97 93 97
96 96 95 100 95 97 91 97

Sat 110 at 4:37 P.M

- - - - - - - 94
- 94 - 95 - - - -
- - - - - - - -
- - - - - - - -

Sat 119 at 4:38 P.M.

- - - - - - - -
- - - - - - - -
- - - - - 98 0 96
51 98 82 98 0 98 0 98
 
This is definitely strange. I think we can rule out the dish itself, because you say the ones in the house have no problems. That means something somewhere between the dish and your shop is bad. But you have replaced every single component, including the cable?

Edit: Has anything at all changed in your shop setup? Extra power lines? Power Tools? It sounds like you may be getting some sort of interference, heat related.

Edit #2: Since you already have extra cable, try running it with a different route.
 
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I'd haul the receiver into the house proper, plug it in and see what happens.

If your garage is getting hot enough, any receiver may fail.
 
Harshness has a point. Your old receiver may have been better at working under high temperatures. The new ones may not be able to operate properly at high temps.
 
Welcome to my Twilight Zone! The new cable is just laying on top of the ground (grass) now as I haven't re-buried it yet. No changes in shop equipment or anything like that. My shop is a separate insulated building from the house that is heated and cooled and dehumidified. It stays at around 72 degrees and 55%. I tried a total of five receivers out there. The two old RCA's that I had. The two new ones DTV sent me last week and the tech had a new one he tried last week as well. We verified there was good voltage to the receiver. My Fluke showed 120.4V. Keep thinking guys and thanks again.
 
I'm stumped. I'll throw some suggestions out though, as you never know.

Bad ground in the electrical outlet? Try running an extension cord to a different circuit.

Flourescent lighting? Sometimes they can play havoc.

Add a new dish for your shop.
 
Ditto on the stumped JMIKEH. I actually was going to try your first suggestion last night and plug the receiver into a dedicated outlet, but when I went out at 9:30 (it was cool) to do that all channels were working good. Signal strengths on Sat 101 were all at 95 and above and steady. I am going to try this suggestion today when it gets hot and the problems begin again. As to the lighting, I do have 144 LF of flourescent lighting in my shop and I can easily check it's effect by just turning the lights off today when it get hot to see if it makes a difference but the lighting has been unchanged for the last two years. Thanks
 
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