NOW IT'S HERE. NOW IT'S GONE. 70% QUALITY TO 5% QUALITY...?

[T4Runner]

I am experiencing C Band for the first time like many reading and posting here. My experience is nowhere near the frustration of Dee, who has a record breaking thread under C Band. But, I am getting frustrated... I have installed around 40-50 KU Band dishes but no C Band until this one.

I can get my Zenith Satellite (AnikF3 @ 119W) locked in at 70% Quality and leave it there with no motor movement and after a while it drops completly out? It comes in usually as the sun sets and stays through prime time. It can be there before the sun comes up, but once the sun comes up, it goes out?

Is it possible to be locked at 70% and lose quality due to it not being correctly centered? LNB skew? I had the dual LNB zero set at 3'0clock at the zenith sat? No amount of tweaking seemed to change the Q.

5FT diam solid steel dish (an old Echostar)
Old 24" actuator w/no name still working.
OpenBoxS9 for a receiver (also using a GeoSatPro 200c for quality checking which is another story. the quality is quite different 45% vs 70%).
VBox from WSI
Very short direct dual coax (less than 50ft)
No switches.

Suggestions?

 

[gardo403]

with my openbox I've been having drop outs on the vertical side of both c and ku ( two separate dishes and lnbf's)..... Ive been reading something to the effect that the voltage for vertical is to high causing the lnbf to flip over to horizontal

The problem seems to worsen when the box is left on for longer periods... just my 2 cents...

 

[T4Runner]

with my openbox I've been having drop outs on the vertical side of both c and ku ( two separate dishes and lnbf's)..... Ive been reading something to the effect that the voltage for vertical is to high causing the lnbf to flip over to horizontal

The problem seems to worsen when the box is left on for longer periods... just my 2 cents...

I do leave it on and do not turn it off. That may be a factor. I also have it sitting on a shelf unit attached to the bedroom wall above a flat screen. Also have another sat receiver (Lexium7000) above it, so I suppose heat could be a factor effecting the receiver.

 

[Pixl]

That is quite a difference to go from 70 to 5%, but I had the same thing happen on my OpenBox when it was about 5 months old. Turned out to be the lnb voltage was dropping off to 7v. while under load (connected to something). It was replaced by my dealer in warranty, new one is fine.
Does this happen on the Geo?

 

[FaT Air]

but once the sun comes up, it goes out?

Could it be the sun warming the LNBF enough to cause a problem?

voltage for vertical is to high causing the lnbf to flip over to horizontal

I had this happen with a Pansat 9200 and a BSC421. The voltage, I thought was too high, so I put two chassis 'F" connectors on a metal box and wired a diode to the center pins. Installed with the banded side of the diode to the BSC421. No degradation of signal noted, but it reliably switched polarity. (I later added a 100pf cap across the diode, just for giggles) Replaced the 9200 with an Openbox, removed box with the diode, Again-No Vertical polarity, so I re-installed the box with the diode. Now I think the problem is the BSC421. NOTE: There's also a DISEQC sw selecting various Ku lnbf's and the BSC421. Never had this polarity problem on Ku, Only the BSC421. Didn't notice this as caused by heat as it was mid winter. +20f. A bit more investigation finds that my BSC421 will only reliably switch to vertical with the voltage going below 13v. The Ku lnbf's reliably switch a good 1 to 1.5 volts higher

 

[Anole]

Interesting observations. :up
In Dees case, I think she got a no-name C-band LNBF against recommendations for a C2.
And she has a PC-based sat system, using an ??? PCI card.
Wouldn't it be funny (not funny-haha, but funny-sad), if she had a high or low voltage problem all along?
Diagnosing these problems really -does- require spares to replace all components in the system.

 

[Pixl]

Diagnosing these problems really -does- require spares to replace all components in the system.

Actually I used a two way splitter that passes power to both ports to measure the lnb voltage under load. Alternately one could add a short length of coax with a notch cut thru the side of the vinyl jacket and shield exposing the center conductor where you could measure the voltage.

 

[T4Runner]

....Does this happen on the Geo?

Good question. I will be checking. After all the rain storms are over here. Supposed to be 80 degrees soon, but rain today and tomorrow.

 

[T4Runner]

Interesting observations. :up
In Dees case, I think she got a no-name C-band LNBF against recommendations for a C2.
And she has a PC-based sat system, using an ??? PCI card.
Wouldn't it be funny (not funny-haha, but funny-sad), if she had a high or low voltage problem all along?
Diagnosing these problems really -does- require spares to replace all components in the system.

I should have a better handle on the voltage issues but I am getting tired of the whole issue... (shades of the Dee scenario...;>)

I'll come back to it after the rain.

 

[Magic Static]

Not that you need anymore things to consider but this reminds me of a time 20 years ago living in Loveland CO. I had the same problem with my cable service in reverse. There in the day when I was at work but gone when the sun went down. I had to take several days of of work so they could discover a "cold suck out" in a spur line connection. The whole neighborhood was out and I was the only one complaining. But all the trouble was a coax connection. Can you say 'Stabilant 22A" ?

 

[T4Runner]

Okay I couldn't stand to wait.... after my kids, grankids, etc left yesterday evening and it was a blisfully sun filled day.... the sun went down and...

I turned it on at 8:30pm and moved the dish from 99W to 91W by manually holding the East button on the VBox. Got the QUALITY again on 91W and did a blind scan on the OpenBoxS9. FX East and West etc, all popped in at 70% QUALITY...

So I switched to the GeosatPro (as suggested above) and blindscaned again. Same thing except it pulled in the free radio channels that the OpenBox missed..

Before I Watched a movie I switched back and forth between the two receivers as I am using a WSI Model DMX242 and running dual coax to the bedroom TV...

OPENBOXS9= 80% SIGNAL 73% QUALITY
GEOSATPRO= 70% SIGNAL 45% QUALITY

Went to sleep.....

Woke up @ 5:00 am before sunrise... grabbed my coffee and quietly tuned on the TV and hit the moot button to ensure not disturbing the other side of the bed....

Input to the OPENBOX same good quality. Input to the Geosat same good quality. Between 5am and 7am we had rain, hail, wind and downpour, with NO picture degradation.

Then the sun popped out and it started pixelating! lost picture after a few minutes on both receivers.

So... not the receivers. Not the Coax. and remember this is a 5ft C Band.

Must be the LNBF?

 

[FaT Air]

OK, I took my time and reviewed, so here's my 2cents.
I think it's solar noise. Sun hits the grass, dirt, whatever, behind and around the dish and gets reflected back to the LNBF. Assuming the feed is perfectly centered and square, First thing I would try is adjust the scalar for a tighter pattern. if its set to .38, set it to .42 or more. The feed will see less of the dish, but may filter out the interfeerence more than the loss of signal.
Then there's the metallic triangles you can affix around the the edge of the dish I remember seeing, and reading about, BITD. (havent been able to find anything on the Internet about these)
An LNBF with lower noise figure MAY work, But I think the solution that will cure this is a bigger dish. as a bigger dish exhibits more gain on the signal of interest. The larger gain is sufficient to overcome the cumulative system noise. LNBF, Dish, receiver and location. You can lose a few 10th of a db of noise with a better LNBF, but is it enough. A 5 ft dish exhibits around 33db(?)* gain, a 10 ft probably 43db(?)*. Not going to find a LNBF that's 10db quieter. NOTE:*=from memory

 

[linuxman]

Paint the dish with a flat black or flat charcoal gray paint, and see if it's not reflecting sun blockage into the feed-horn. :yikes:

 

[Pixl]

I'd vote for a bigger dish.
Painting it black will only absorb visible light. The sun also generates energy in the radio spectrum along side the microwave frequencys we desire. Paint has little effect on RF including the Sun's RF.

 

[linuxman]

I had a 6 foot home-made steel dish setting on 107W for over a year. It was painted white, but I never had a problem with signals.

 

[FaT Air]

Earth Thermal Noise (ETN) this link > Satellite Footprints by Dish Size - Noise Discussion < AMC3 (87w) is quite a bit east of T4Runners location, 37.0N 119.5W. Therefore the "noise floor" is higher, because the dish is aimed closer to the horizon. This would also aim the dish in the general direction of the morning sun, further increasing the noise. [Quoted from above link]

Side lobes of a larger dish are smaller in comparison to its main lobe so a larger dish receives less per cent noise per signal as compared to a smaller dish

Address: 37.0000, -119.500
Satellite: 87W AMC-3 (GE-3)
Elevation: 35.2°
ETN= ~70°K with a 5ft dish(extrapolated)[from chart at link above]
Address: St. Louis, Mo
Latitude: 38.6470°
Longitude: -90.2250°
Satellite: 107.3W ANIK F1 | ANIK F1R
Elevation: 41.8°
ETN= ~50°K with a 6 ft.[from chart at link above]
Think 20°K, alone, could make a big difference.
Aim is west, away from the morning sun, and higher. Both of these factors will lower your "noise floor"
From the chart, there is approx a 25°K reduction in ETN between a 10 ft and a 5ft dish at 30 degrees elevation. Then, there is also the Eirp from the desired sats TP's to consider. I am thinking the only way to know for sure is a spectrum analyzer. See if it's the TP signal fading out, or the noise floor rising, gobbling up the TP.
I still say, if there are no equipment malfunctioning,(which I think is the case) the way to go is a bigger dish. We could also use someone in the area of 119w, with maybe a bigger dish, to chime in.

 

[T4Runner]

I think Fat air has a valid point for my dish. I might need to spend some more time tweaking (groan...standing on the stepladder) the LNBF to see if it makes any difference. Since this is a 5ft c band dish I knew there would be frustration moments with signal quality failing, but this is very strange and tiresome.

Incidentally, I have a guy trying to give me an all metal c band that looks to be 8ft or so,but I have no boom to get it down. I would prefer the perferated dish anyway. The all metal 8ft must weigh a ton? It looks like a bigger version of my 5footer of thin sheet metal painted gray.

Thanks for taking the time to think through this and posting the comments. It is appreciated. It's not as frustrating though as it was this am when I was re-pointing a 30" dish for a guy and it took an hour to lock the satellite between four 60ft redwood trees... finally got it locked at 73% and quit while I was ahead.

 

[T4Runner]

FAT AIR, I meant to tell you that my due South sat of AnikF3 drops out too, so I am thinking about the feedhorn because when the sun comes up the dish is sitting in a position where only the LNBF is getting heat directly with no reflected heat.

I just don't want to move the dish right now because I like FX East and West where it's currently parked...;>)

 

[Anole]

... this is a 5ft c band dish...

I have a guy trying to give me an all metal c band that looks to be 8ft or so,but I have no boom to get it down.
I would prefer the perferated dish anyway.
The all metal 8ft must weigh a ton?
It looks like a bigger version of my 5footer of thin sheet metal painted gray.

A number of gems have been discovered laying out for anyone to take.
Get us some pictures of the dish, both front , 'n back, and the motor.
If you have a dud, we can probably tell.
If you have a gem, we'll beat you 'till you go bag it. :up
But a -good- 8' solid is gold.

As for weight, most I've seen are aluminum.
My Birdview 8' solid is aluminum, but it's built like a tank. So, yes, it's a little bit on the heavy side.
My AMCI 8' perforated is also spun aluminum, and while sturdy, it's a dream to handle.
Saw a frellow on the forum a few years ago with a one-piece spun aluminum 10' dish.
He was a big guy, but he managed it okay.

 

[Indy]

Check for ants in the LNB. Yes, ants as in insects. For some reason ants are attracted to the electronics and current in the darn things. I have this problem every spring and have to evict the critters. They build a nest inside the LNB's and cause problems just like you have described..