Only -32c, DMX-741 Hibernating?

[upnatm]

Anyone else with cold problems on the DMX-741?

Reception went down last night when the temp dipped under -30c, was on a Ku sat at the time. My first try was to go into dish setup and toggle the LNB power. Strength came back to 100% for about 10 seconds, and hasn't come back since.

My next thought was "AZ-Box power supply!", but it passed the bench tests for 12 & 24 volts.

I've tried 3 different stbs on C and Ku, I also bypassed the G-Box. The problem must be along, or at the other end of the 120' cable.

My DMX-741, and cables were new last June, and have survived -28c already.

32 below, I think I'll let the sun play on the black nose-cone first, before I venture outdoors.

Can anyone tell me of any other tests that I can do at the "warm" end of the cable? Ohms?

Thanks for your time, Brrrrrr!

 

[Lak7]

What is the Signal Strength?

Does the Signal Strength change if you disconnect the Cable from the back of the AZBox?

 

[Cham]

We had about the same temperature yesterday morning and the 741 here was still working fine. I don't have one of those large black covers for that dish though. Have you cleaned the snow off the dish? Also frost might be heaving or moving the mount... might want to check if the mast is still vertical. The 8' dish I have the 741 on here is only sitting on a metal base on the ground and it moves a bit as the ground freezes. The dish has no motor so it doesn't need to track the Clarke belt so I just re-aim it once in a while when the signal drops.
Keep warm!
-C.

 

[upnatm]

Hi Cham, nope, no snow on the dish (10' mesh), and I think the frost would've acted on the mounts a while ago, and not as quick
as like how suddenly my signal vanished last night. Hey, the wife gave me a "digital level" for Xmas, I'll check the pole first, when I get out there!

The signal strength just dropped, all of a sudden, from 100% to 19%, and no, Lak7, no change in the strength while connected or disconnected.
Although, there must be proper voltage coming from the AZ, because the G-box will respond to it, and the dish will move.

I pressed the core conductor of the co-ax into my thumb and the signal strength rose by 4%!, lol, so I'd say the AZBox's meter is fine.

Phone rang, it took me over an hour to post this reply.

Well, the sun's been hitting it for a few hours now, and BINGO!, everything has come back to normal! Son of a gun! I never got out to
jiggle any wires, so I don't know exactly where the bad spot is!

I might just go out and stick some insulation inside the nose-cone, and put a 25 watt refrigerator bulb in there too. If I get the same problem tonight,
I'll just plug in the light-bulb to see if that fixes it!

Thanks for the interest in my situation. I'll be back.

 

[FaT Air]

Check the center conductor of the coax connector at the lnb, and any other outside connection. If it's short, cold will shorten it more, and could disconnect.. I've seen this happen more than once. I like to leave 1/8th inch of the center conductor extending past the connector body

 

[upnatm]

Quote: "If it's short, cold will shorten it more," Thanks FaT Air.


Y'know, I bet you nailed it! I put the connectors on myself, and I bet they likely are on the short side!
And since I lost both C and Ku at the same time, it'll be the long cable and not the jumper.

It's supposed to warm up a little tomorrow, I'll bring a new end up then.

Damn!, I just remembered, I have a barrel connector in that line, about 20' this side of the dish.
I'll just do the LNB connection first, then sit back and wait.

Thanks again guys! I appreciate the help!

 

[Cham]

Had that problem on an N connector on a 400' piece of heliax once. Antenna worked great until the temperature dropped below about -20c. Worked just like a thermometer. Of course it was the connector at the top of the tower 350' up... Original installer used a clamp type connector and left a space between the dielectric and the connector insulator by not pushing it in far enough before tightning the nut.
It wasn't -20 when I replaced the connector, that one had to wait.
I think F connector specs call for 1/8 protrusion past the body anyway. Makes the connector easier to line up.
C.

 

[tuberadio]

Temperature here last night dipped to -37C and my DMX741 was working like a charm.