COLD LNBF C band

[danristheman]

I am having trouble with a cband lnbf when it gets below 20 degrees it acts up but when it warms up to the freezing point 32 it works great. Any one have answers to this question? It can barely get 99w cband even when its locked on only picks up a few transponders. the other hand I am getting 95w CBS channels that has a 41 eirp value.

Dan Rose

 

[KC9TIK]

I'm waiting for the weather to warm up so I can do more testing. I have the same problem on 99 also. The Amiko refuses to get the 8psk transponders when cold outside, but the 6981 works near perfect. There was one time the Amiko had perfect picture when the 6981 had problems. I also have that lnbf 8 degrees off prime while the 95 is 4 degrees off prime.

Have you considered wrapping it in insulating foam to keep the heat in?

 

[primestar31]

Strap and old-school incandescent nightlight underneath the lnb, and plug it in. That should keep it just hot enough to keep it going. Sort of like an egg incubator...

They are around 3 or 4 watts, and you should be able to buy one cheap at Wally-world, or might even have one stashed somewhere already.

 

[markbone100]

Water got in it and is freezing?

 

[Titanium]

Try a blind scan. Maybe the DRO LO is drifting in the cold?

Satellite signals are typically better in cold conditions.


Brian Gohl
Titanium Satellite

 

[skysurfer]

Satellite signals are typically better in cold conditions.

or there is rust or other issues with the inside part of the connection of coax/LNBF that cold contracts the metal just enough to make a suspect connection.

 

[Vondertrenk]

I agree with Titanium; I am receiving a lot of new channels since winter started, the cooler the better. I am close to Toronto and as of today is only 11 F.

 

[danristheman]

DRO? My lnb freqency is 5150 using the micro HD all my ku band equipment working just fine. I have a plastic bag under neath the cover for the lnbf and a country crock butter lid for the conical scaler.

 

[KE4EST]

DRO? My lnb freqency is 5150 using the micro HD all my ku band equipment working just fine. I have a plastic bag under neath the cover for the lnbf and a country crock butter lid for the conical scaler.

DRO=Dielectric Resonator Oscillator or in laymens terms NON-PLL the ones before PLL came out.

Crontry Crock Butter Lid? Not understanding this. I could see maybe a bowl, but it would need to be lined with foil, to even work.

 

[Titanium]

DRO? My lnb freqency is 5150 using the micro HD all my ku band equipment working just fine. I have a plastic bag under neath the cover for the lnbf and a country crock butter lid for the conical scaler.

Correct! The LNB LO frequency for your C-band LNB should be 5150, but as DRO LNBs age they often drift off of this frequency. This drifting also happens during extremes in heat and cooling. The cold temperatures may be causing your LNB LO to drift off of 5150 and the receiver's automatic fine tuning circuit cannot compensate for extremes.

My suggestion to Blind Scan the satellite for the missing channels. The STB might log them at a slightly different frequency. If you do a blind scan and find the channel(s) coming in at a slightly different frequency, then you will know that the LNB LO frequency is drifting and would be a candidate for replacement.

If the plastic bag isn't letting moisture escape, it may be building up inside the feedhorn, or freezing on the plastic. Water or ice on the feedhorn cover will cause a lot of signal loss.

Also, metal dishes flex and distort with temperature extremes. As the metal chills or heats, different areas of the dish contract or expand at different rates, causing the dish to lose the parabolic shape and not properly reflect the signal into the feedhorn. Composite or fiberglass dishes usually do not have this problem.

 

[KE4EST]

Sorry missed your call earlier Dan, but what dish is this on? The 1 meter or 1.2 and is it fiberglass?
Brian's explanation of the possibilities was excellent, but to add to it, when you are using an undersized dish these things are multiplied and happen very easy. If for example you were using a 10 foot dish, what Brian said still applies, but may not be noticed because of the larger dish.(well all but the drift in the LO, that can still show up in a 20 foot dish )

 

[wallyhts]

DRO? My lnb freqency is 5150 using the micro HD all my ku band equipment working just fine. I have a plastic bag under neath the cover for the lnbf and a country crock butter lid for the conical scaler.

Got to see a pic of the country crock lid in action.

 

[primestar31]

Got to see a pic of the country crock lid in action.

I stole this off the 'Fridge:

I've seen others with lids, but I can't remember where. Maybe legalfreetoair.com, and I think it was from Carlospr43...

 

[danristheman]

Brian I think you might be right it is drifting some what than around normal warm temps when working fine. The dish that I am using is a 1 meter fiberglass dish with the cali amp cband lnbf on it. I might have to take off the cover and let it breeth little bit to see if it helps. I will take some pics of it as soon as I can.

Dan rose

 

[Titanium]

Be sure to coat that cover with RainShield or RainX to bead the water. Water streaming on that big cap would quickly attenuate signals during a downpour.

 

[Vondertrenk]

A lot of this can be avoided by just replacing the existing DRO LNB with one of the new Titanium PLL LNBs. I recently bought two, one for circular and other for linear polarization and so far I have not had those problems this winter.

Correct! The LNB LO frequency for your C-band LNB should be 5150, but as DRO LNBs age they often drift off of this frequency. This drifting also happens during extremes in heat and cooling. The cold temperatures may be causing your LNB LO to drift off of 5150 and the receiver's automatic fine tuning circuit cannot compensate for extremes.

My suggestion to Blind Scan the satellite for the missing channels. The STB might log them at a slightly different frequency. If you do a blind scan and find the channel(s) coming in at a slightly different frequency, then you will know that the LNB LO frequency is drifting and would be a candidate for replacement.

If the plastic bag isn't letting moisture escape, it may be building up inside the feedhorn, or freezing on the plastic. Water or ice on the feedhorn cover will cause a lot of signal loss.

Also, metal dishes flex and distort with temperature extremes. As the metal chills or heats, different areas of the dish contract or expand at different rates, causing the dish to lose the parabolic shape and not properly reflect the signal into the feedhorn. Composite or fiberglass dishes usually do not have this problem.

 

[Cham]

I have never has trouble with an LNBF not working in the cold... even when it gets down to -40 or more. I have had one quit during coldish weather but it wouldn't recover when warmed, likely just died...

I have had other cold weather issues with outdoor equipment though... If you have a long length of feedline, the center conductor can shrink enough to actually pull out of the connector terminal at one or both ends. Copper is usually forgiving, but the stainless steel core "copperweld" in some RG6 cables seems to be a bit worse since the steel won't "streach" as it cools off and shrinks. To remedy this I have left an extra 1/8" exposed when putting on the cable connector on long cable runs. Check the recepticle first to make sure it allows for the extra length... or you could have trouble when it gets hot out... sometime...soon I hope!

 

[KE4EST]

Yes can't wait for warm weather!!

 

[Vondertrenk]

I am not saying hte LNBF will not work on cold weather, but it is a fact,as Titanium said above, that the oscillator tend to drift in frequency so you may still have some active TPs and may lose some others; you may need to rescan to recover those channels. The end result is that those channels will be available in other TP that is slighly different that the original one.

I have never has trouble with an LNBF not working in the cold... even when it gets down to -40 or more. I have had one quit during coldish weather but it wouldn't recover when warmed, likely just died...

I have had other cold weather issues with outdoor equipment though... If you have a long length of feedline, the center conductor can shrink enough to actually pull out of the connector terminal at one or both ends. Copper is usually forgiving, but the stainless steel core "copperweld" in some RG6 cables seems to be a bit worse since the steel won't "streach" as it cools off and shrinks. To remedy this I have left an extra 1/8" exposed when putting on the cable connector on long cable runs. Check the recepticle first to make sure it allows for the extra length... or you could have trouble when it gets hot out... sometime...soon I hope!

 

[Cham]

Have you tried another receiver with that particular LNBF? Drift can occour in both the LNB(F) and IF stages (receiver), but the LNBF is the most likely culprit. That is assuming the supply voltage to the LNBF is consistent (relative to polarity signal), as I expect there could be LO drift with voltage changes on some of these devices.