Can the cold affect the LNB?

[Greg Mueller]

This is making me crazy.
Put on my new jack today and tweaked everything in.
Here is what I was getting for Qs

G3 79
W5 99
G0 95
C3 68
G1 74

The sun is setting now and the temp is going down
C3 is now 38 and sometimes I lose it.
G1 is still about where it was
G0 is down to 38 or so as well
W5 is still at 99

I've checked the coax and it looks like new at the lnb.
This is making me crazy

 

[Greg Mueller]

PS
Using a brand new Norsat 8115

 

[Greg Mueller]

It gets weirder

The screen froze up and so I switched to the adjacent channel and back again.
Now the signal is 66

 

[Mr Tony]

How far of a cable run?

I had one of the voltage sensored LNBF's die in the Minnesota winter and not work on H polarity but that was below 0
http://www.satelliteguys.us/c-band-...88610-can-cold-kill-one-side-c-band-lnbf.html

 

[gmd63]

It gets weirder

The screen froze up and so I switched to the adjacent channel and back again.
Now the signal is 66

I just posted the same type of question in another section. This is happening to me as well since the colder weather hit, I am in the same sort of area you are.

I turn it off and on and flip it back and forth till it comes back to normal. I have a cheapo LNBF on mine though.
I have a back-up to put on but it is only a single output and the one I'm using now is a dual.

 

[tvropro]

In the old days LNB's worked better as it got colder. What may be happening is the the thing is drifting a too much when it gets cold. Thats causing the quality to take a hit. Norsat was a good LNB back in the day. If you have something else to sub it with try it, that is the only way to isolate it. Or send it back and get another one. If the coax is good there is nothing else but the receiver that could be bad. But it works good when it's warmer and unless your receiver is outside getting cold it shouldn't change.

EDIT: Just a thought... Is the polorotor (servo) motor possibly sticking when it gets cold. That would cause your symptoms. What tipped me off is when you switched channels back and forth the quality changed. Think about it if the polarity probe sticks because the polorotor motor is sticking the quality would suffer. Try going to analog channels like 11 and 12 on G1 and change back and forth when its cold and see if you can see crosspolor in the analog video.

 

[Greg Mueller]

EDIT: Just a thought... Is the polorotor (servo) motor possibly sticking when it gets cold. That would cause your symptoms. What tipped me off is when you switched channels back and forth the quality changed. Think about it if the polarity probe sticks because the polorotor motor is sticking the quality would suffer. Try going to analog channels like 11 and 12 on G1 and change back and forth when its cold and see if you can see crosspolor in the analog video.

I was just thinking that.
I think I'll pull the polarotor gizmo off tomorrow and check it and maybe give it a drop of oil.
Funny how by just changing channel back and forth it popped back up to full strength

Iceberg
The cable run is about 100-125' (maybe)

 

[Anole]

Did ya see this relevant discussion by TruckRacer?
http://www.satelliteguys.us/c-band-satellite-discussion/195867-unstable-lnb.html

 

[LocutusOfBorg]

This is making me crazy.
Put on my new jack today and tweaked everything in.
Here is what I was getting for Qs

G3 79
W5 99
G0 95
C3 68
G1 74

The sun is setting now and the temp is going down
C3 is now 38 and sometimes I lose it.
G1 is still about where it was
G0 is down to 38 or so as well
W5 is still at 99

I've checked the coax and it looks like new at the lnb.
This is making me crazy

I get a performance improvement especially on NETV DCII (T4) when it gets below 15 degrees. I don't know what causes this as I've changed my LNB 3 times trying to resolve the issue.

 

[tvropro]

I get a performance improvement especially on NETV DCII (T4) when it gets below 15 degrees. I don't know what causes this as I've changed my LNB 3 times trying to resolve the issue.

That is because the noise temp of the LNB (Kelvin) and the thermal noise of the ground etc gets lower as it gets colder. Used to happen all the time in the old gasfet 55-120 degree LNB's and LNA's.

 

[tvropro]

I was just thinking that.
I think I'll pull the polarotor gizmo off tomorrow and check it and maybe give it a drop of oil.
Funny how by just changing channel back and forth it popped back up to full strength

Iceberg
The cable run is about 100-125' (maybe)

Its sticking or going bad. I would get a new motor, there cheap. If I had to bet a new motor will solve all your problems .

 

[LocutusOfBorg]

That is because the noise temp of the LNB (Kelvin) and the thermal noise of the ground etc gets lower as it gets colder. Used to happen all the time in the old gasfet 55-120 degree LNB's and LNA's.

I guess I keep buying junk LNB's? One is a Norsat (forgot model number).

 

[Greg Mueller]

Changed out the 8115 for a spare LNB and was able to determine that it definitely is the servo.

I watch G3 (Fox) which is a vertically polarized channel while the sun is going down.
So I guess the cold gets to the switch and no horizontally polarized channels will work after that.


Now to find a cheap yet good servo switch

 

[truckracer]

cold affects my system quite a bit if you pay attention to quality numbers. I am not talking about losing reception but quality take a little bit of a hit when it gets below 25 degrees.
ku does not seem to be affected but the c band lnb my cheapos and even my norsat 8115 (new) suffers a little bit.

 

[tvropro]

I guess I keep buying junk LNB's? One is a Norsat (forgot model number).

Honestly if you could find a good used late 80's early 90's Cal Amp HEMT 40-45 you would be doing better than with allot of the so called 17 degree garbage that you can get today. Not only that but the old LNB's had extra circuits in them to filter out out of band TI.

I have a 1989 vintage 40 degree Cal Amp. Very good unit (see attached)

 

[tvropro]

cold affects my system quite a bit if you pay attention to quality numbers. I am not talking about losing reception but quality take a little bit of a hit when it gets below 25 degrees.
ku does not seem to be affected but the c band lnb my cheapos and even my norsat 8115 (new) suffers a little bit.

My quality goes up with cold cold weather. Must be the way LNB's were built back in the day.

 

[tvropro]

Changed out the 8115 for a spare LNB and was able to determine that it definitely is the servo.

I watch G3 (Fox) which is a vertically polarized channel while the sun is going down.
So I guess the cold gets to the switch and no horizontally polarized channels will work after that.


Now to find a cheap yet good servo switch

Contact Mike Kohl at Global Communications: http://www.global-cm.net/ He's a great guy to deal with.

 

[JAS]

Contact Mike Kohl at Global Communications: http://www.global-cm.net/ He's a great guy to deal with.

Thanks for the link I'm having problems with my KU LNB.

 

[emuman100]

In cold weather, my Norsat 8115 and Nortsat 8515 perform much better. Much better eb/no on DCII channels. Norsats now are still made very well, at least in my experience. I have a dual output feed and two feedlines for both the H and V LNBs, so no moving parts.

 

[Greg Mueller]

In cold weather, my Norsat 8115 and Nortsat 8515 perform much better. Much better eb/no on DCII channels. Norsats now are still made very well, at least in my experience. I have a dual output feed and two feedlines for both the H and V LNBs, so no moving parts.

How do you switch between H & V ??