Average KU loss on rainy day

[truckracer]

I have been noticing ku levels on rainy days vs sunny days.
On average with my pansat 9200HD signal quality meter it looks like 20% loss is average for rainy days vs sunny days on KU band for me.

I know all recivers are different in the way their meters display readings.

Thought some of you may find it interesting.

 

[goaliebob99]

For me I havent noticed any diffrence, unless its poring.

 

[rv1pop]

What do you consider a rainy day? The Seattle area has (very occasional) clear days, Weather, drizzle, rain, hard rain and stormy rain! One of the weather forecasters will tell you when you get sun breaks in you area as he shows the map! What we noticed was when we got sunbreaks or signal quality would go up!

Washington is know as the EVERGREEN State - Grass, mold, moss, slime!

Of course that is why we moved to the dry side. No one told me about the wind! Peak at52 MPH 2:20 yesterday afternoon average 45.2 around that time. That is when I often lose signal!

 

[gpat]

What do you consider a rainy day? The Seattle area has (very occasional) clear days, Weather, drizzle, rain, hard rain and stormy rain! One of the weather forecasters will tell you when you get sun breaks in you area as he shows the map! What we noticed was when we got sunbreaks or signal quality would go up!

Washington is know as the EVERGREEN State - Grass, mold, moss, slime!

Of course that is why we moved to the dry side. No one told me about the wind! Peak at52 MPH 2:20 yesterday afternoon average 45.2 around that time. That is when I often lose signal!

Isnt that the state you take you pet goldfish for a walk?

 

[Anole]

good news; bad news

Washington is know as the EVERGREEN State - Grass, mold, moss, slime!

Crap! Sounds like Florida -

Of course that is why we moved to the dry side. No one told me about the wind!
Peak at 52 MPH 2:20 yesterday afternoon average 45.2 around that time.

I can see where your suburb will get its power from: wind turbines! - :up

One thing they put in here 100 years ago for the orange groves, were wind breaks of eucalyptus trees.
They grow high and strong, and last a long time.
Smells good, too.


As for the topic of this thread, I have no experience with rain fade.
And not too much recent experience with rain... -

 

[Pismire]

Isnt that the state you take you pet goldfish for a walk?

Nope, we all have pet slugs.

 

[mikekohl]

Advice:

I have never seen a 3-foot solid offset antenna that did not outperform a 10-foot mesh antenna on Ku-band. Did an A/B comparison back in 1996, when TV Ontario was still a clear analog channel on 107.3/Ku Band, using a 10-foot mesh antenna, a 7.5 foot Paraclipse HYDRO solid antenna, and a 3-foot offset antenna. When it rained, the 10-foot mesh antenna was the first to lose the signal, because of a lack of efficiency and the narrower beamwidth...which meant it blew off satellite with just a little wind.
During clear weather, the 7.5 foot PARACLIPSE solid outperformed the 3-foot solid offset dish by a significant margin. However, when it rained, there were times that it rained so hard that there was little trace of the signal left on this otherwise great 7.5 foot antenna. At the same time I found that I did not lose signals (or my recordings of Heartbeat, a British series) on the 3-foot offset.

The secret: Offset antennas are typically pointed 22 degrees lower than a prime focus antenna. A 36 degree incoming elevation on a prime focus dish(solid) during a heavy rainstorm caused rain to puddle and build up on the surface of the HYDRO antenna...and wipe out the Ku-band signal. The offset dish, because it was physically pointing at an angle around 15 degrees back from vertical, did not have any rain staying on the surface, so the signal was not adversely affected.

Moral of the story is that you should consider at least an 80 cm, and preferably larger offset antenna for use on those rainy days when your big mesh antenna is not up to the task of staying locked in to those Ku-band signals.

 

[truckracer]

Thanks Mike,
I have been knocking myself out wondering why this big huge 10' antenna is just not blowing the signal quality meter out of the receiver. I have tuned like you would not believe. My C-band reception is super on the 10' (which I guess is what it was really meant for) it is however rated for ku. It is a Sami SI-10.

My 7.5' Sami never loses KU band in the rain. This 10' does not lose signal but it takes a good hit of 20% or more.

My new C/ku Corotor should be here tomorrow. I am hoping to get a little more out of it with this new feedhorn and Norsat lnb's.

Mike,
I do not have a feed cover (black plastic bucket style cover). Will it hurt my feedhorn or servo motor to leave it out in the rain and sun?
I know I have read somewhere that people have mixed emotions on feed covers.
I don't want my investment dying an early death to weather elements.

Thanks for all the help.

 

[mikekohl]

It would be advisable to cover the Feedhorn/LNB junction as well as get
all connections out of direct exposure to wind, rain and sun.
If you don't want to spend big dollars on a new cover, we do have some
closeout bargains on weather covers only...you'll have to drill or punch holes
and attach with cable ties to the quad legs. Illustrious names such as SEARS,
RADIO SHACK and even some unmarked covers. Cheaper five at a time,
because the shipping charges are about the same for one versus five covers
in the same package. PM me if you're interested--I couldn't say no to a couple of lifetimes' worth of old covers, and they are really getting in my way.

If you don't use a cover, be sure to put some coax seal (looks like blackjack gum) on the coax connections, and/or clear electrical rated silicone grease inside the connectors to keep out water. Also silicone the LNB/Feedhorn
junction after tightening the hardware, and make sure you have a gasket in between.

There are different opinions about weather covers. After seeing a few uncovered installations that were in the sun over ten years, I must comment that a sunshade is a good idea to minimize fading on paint and labels, as well as to limit the about of precipitation directly landing on the components.
In hot regions, it is best to vent the bottom of these covers. Black covers catch more solar radiation, and therefore raise the temperature on the LNBs and feedhorn...but it's less than if they were directly out in the sun.
As a poor man's compromise, I would use the bargain covers mentioned, so that there is a complete opening on the end facing the feedhorn. Tie a small mesh bag of moth balls inside, to encourage birds and rodents to keep looking for a new home.

 

[rv1pop]

Crap! Sounds like Florida -
I can see where your suburb will get its power from: wind turbines! - :up
Yes, we can now see over 200 windmills from our property!
One thing they put in here 100 years ago for the orange groves, were wind breaks of eucalyptus trees.
They grow high and strong, and last a long time.
Smells good, too.
We have not been able to get trees to take root yet because of the wind.

As for the topic of this thread, I have no experience with rain fade.
And not too much recent experience with rain... -

We have been accused of bringing rain from the Puget Sound to the county. They have had as much rain here last winter than they had total in the previous 7 years! And twice as much rain so far this year than last year! A few days ago we did lose most signals in the snow, but it was snowing so hard we could not see the end of our driveway! This was not from piling up, but from the snow in the air.

POP

 

[truckracer]

Thanks Mike,
I hope i get better ku performance from the corotor. What do you think?
Would you say in a given situation the corotor is going to out perform the bsc 621?
This c/ku lnbf really is not cutting it on ku after hours of tuning. No amount of tuning is bringing in satifactory ku IMO.

 

[mikekohl]

Any veteran of this business that is completely honest and knowledgable will have to admit that a C/Ku feedhorn with polarizer, such as the Chaparral Corotor II or ADL RP-3, will outperform a C/Ku LNBF. While C/Ku LNBFs are inexpensive when compared to separate components, there simply is not the same level of isolation between polarities as well as between C & Ku band.

California Amplifier tried for years to create a C/Ku LNBF, and never brought a product to the market because nothing met their standards for isolation and overall performance. The BSC-621 and similar C/Ku LNBFs are remarkable in what they can do, for something in their price range, but their use and alignment requires a series of compromises. Ku-band performance is generally down in level quite noticably. If you have a large enough (and efficient enough) antenna, your situation may mask some of these shortcomings. Mesh antennas are not efficient by nature, and my cardinal rule has always been that a well-aligned 36 inch solid offset with Ku-band LNBF should equal or outperform any 10-foot mesh antenna equipped with a Corotor II or similar prime focus feedhorn.

If you want better performance, consider the idea of a C/Ku feedhorn with a polarizer and separate C and Ku-band LNBs. If you want flexibility for a multiple receiver system and access to both polarities on C and Ku-band, something such as the ADL 2+2 series dual port C, dual port Ku, and 2 LNBs in each band will work well when fed into a powered multiswitch (typical 4 satellite inputs and either 4 or 8 outputs) normally used for DirecTV systems.
Its only flaw is that there is no polarity fine tuning, so oddball satellites such as AMC-1 at 103 West should either be ignored, or if important...a separate Ku-band LNBF should be pointed for its reception.

 

[voomvoom]

Mesh antennas are not efficient by nature, and my cardinal rule has always been that a well-aligned 36 inch solid offset with Ku-band LNBF should equal or outperform any 10-foot mesh antenna equipped with a Corotor II or similar prime focus feedhorn.

I have to agree with this, but would like to add, in my experience when I compared my 1.2m Fortec dish with my 10' Mesh dish, with a Pansat 3500s and an Invacom QPH031 on the Fortec and a Channel Master 0.8db (I think) on the Mesh. I found the 1.2m Fortec had about 8 Quality points better than the 10' Mesh, but the 1.2m Fortec lost signal when a downpour occured while the 10' Mesh never lost it's signal, but did lose a few quality points. Now, although I primarily use the 1.2m for most of my ku viewing, I'm glad to have the 10' Mesh to fall back on, on the "Very Rare" occassions that it Rains hard enough to lose signal. In other words, there are advantages to having both......

 

[truckracer]

Thanks Mike,
You are always so helpful and accurate. It's good to get a good honest opinion.
My Corotor may be here today and if so I will install it tomorrow. I just can't really live the ku compromise of the bsc-621. I have some tp's on G-25ku that are coming in just above the digital cliff. My receiver (pansat 9200hd) will lock most signals down to 27% or so depending on the FEC. some of those tp's are coming in at 35-40% on ku while others are hitting 80% quality.

On my .76 patriot with an SG-2100 motor and cheap chinese E-bay lnbf (6.99)LOL, I get 60's to 80's quality on most everything on G-25KU. I would imagine a nice Invacom QP series would do better.

I do understand that my big mesh dish will not out perform a small solid on ku, but I do want to be a bit better than it is now.

I hope the corotor will be the answer. I do like have polorizer control. I have never had that option since I have had a big dish. I have always ran c-band lnbf's. I had great performance out of a DmS ASC-421 on a 7.5' sami.

I used to be able to lock the 4dtv HBO/Max channels with the old weak G1 satellite before it got replaced. I remember reading where folks had 8-10' dishes and could not lock on of those tp's .

Mine were always in the high 50's to low 60's on the dsr-905.
my 7.5' sami will lock the hard to get equity mux on G3c. That 29.120 ms/s 7/8 tp.
I was amazed.

Thanks for your help mike.

 

[gpat]

Ive been pondering this for years and wonder if anyone has made a hybrid dish
for Ku.
Use the 10 ft mesh but put a 3 ft circle of solid aluminum pedals in the middle.formed
with the same parabola. Attachment could be via small holes in each corner and tiewraps.
This might help your situation.

 

[mikekohl]

Years ago there were some perf manufacturers that did just that.
Definite improved performance on Ku-band versus the average mesh antenna, and they keep their shape more accurate over time.

However, more substantial issues on Ku-band include the following:

Offset Ku-band LNBFs are much more efficient than feedhorn/LNB combo,
especially since most offset antennas have an f/d ratio around 0.6.
Considerably more gain as well as increased number of sidelobes,
as compared to the typical prime focus antenna with an F/D ratio between
0.3 and 0.4. Sidelobes on an offset antenna are our "friend", as compared to a general hindrance on prime focus antennas. Far enough apart to be mostly non-problematic, and strong enough to utilize multple LNBFs at the same time.

Rain will "puddle" on the surface of any solid antenna, causing major problems with Ku-band reception, especially if elevation is higher than about 30 degrees above the horizon. The elevation gets 22 to 25 degrees more vertical when using an offset dish, so by pure physics, there is little to keep the water on the surface of the antenna.

 

[truckracer]

I put my 76 cm patriot back up out front with the SG-2100 motor. I have not had a chance to install my Corotor yet. I ditched the BSC-621 and put my old Astrotel 20 degree C-band lnbf on my 10' and all my signals got much better on c-band.

My 76cm patriot will pull in low 90's quality on G10R ku 11800V and high 70's 11720V.
That washington tv stuff or whatever it is - gets pretty low here.


G25ku booms in too.

Amc-4 ku is very strong.

Amc-3 ...Have not programmed that one yet - going to try for pbs. and pbs HD.