HughesNet Crosspolling

[jarvantgroup]

I have a scenario where after performing scores of the same type of antenna point and crosspol, my crosspol numbers seem to decrease as the day progresses. Same satellite, same type dish, same general area (give or take 5-10 miles). Generally in the mornings, crosspol numbers of upper 80's are reached fairly easily. As the day gets into the early PM hours, I'm barely able to get upper 50's/lower 60's.

I have noticed in the early morning hours, it has been generally overcast or foggy. Things clear up as the day progresses. A while back, while performing some troubleshooting with a Hughes rep about the low crosspol numbers, the rep asked me to drape a wet paper towel over the feedhorn to improve the crosspol numbers. helped maybe a few points, but not dramatically. That The question is why does the "water/moisture" factor appear to improve the crosspol numbers? And if there is a correlation, can introducing/mimicking the cloudy conditions with wet fabric be the solution when faced with the ongoing issue with the crosspol numbers decreasing throughout the day? Or could there be an issue with the sun's orientation at those early afternoon hours that could be affecting crosspol numbers?

 

[NYDutch]

The wet paper towel could be cooling down the assembly. That could also explain why the numbers are better in the cooler morning hours.

 

[harshness]

Crosspol (cross polarity) is often an issue with the signal being too strong such that there's interference from the other polarity. A wet towel would reduce the signal level to the point where the other polarity is no longer a factor. It may also be possible that there's corrosion or a foreign object in the feed horn that is creating an interference by misdirecting the signal.

 

[jarvantgroup]

The wet paper towel could be cooling down the assembly. That could also explain why the numbers are better in the cooler morning hours.

I do notice that the assembly is slightly warm to the touch. I'll see if the wet cloth over the assembly helps out the next time I'm out. I'd still like to find out why the heat might be throwing the crosspol numbers off. What would be the science behind it.

 

[NYDutch]

I do notice that the assembly is slightly warm to the touch. I'll see if the wet cloth over the assembly helps out the next time I'm out. I'd still like to find out why the heat might be throwing the crosspol numbers off. What would be the science behind it.

The "Why" would be above my pay grade, but the "How" seems logical since the evaporative cooling effect is the only practical reason I can see for the wet paper towel being effective. A wet rag should work as well and likely cool for a longer period.

 

[Foxbat]

To test if it’s a thermal effect, you could try using a can of Dust-Off, hold it upside-down, and spray the heatsink with the propellant. It should rapidly cool down the electronics without blocking any signals.

 

[harshness]

The feedhorn isn't where heat is generated in an LNB assembly. The cooling fins are on the electronics enclosure because that's where the heat is. The metal in the feedhorn has a contribution but probably it isn't substantial.

I'd ice the electronics housing if I thought heat was the issue. It's surely cheaper, lasts longer and is more environmentally sound than Foxbat's suggestion.

 

[Foxbat]

Yeah, using the canned-“air” propellant for cooling isn’t going to win any karma points.