What in the world am I doing wrong?

[Pepper]

I have a ChannelMaster 3040842-02 1.0M-02 (the huge round one - 43 inches high by 40 inches wide). Using the stock feedhorn and a new dual-feed standard LNB. I've tried it on 97W, 99W, and 103W.

This dish is giving me fits. Pointed at the same satellite, a SuperDish (24 inches high by 33.5 inches wide) will consistently provide higher signal levels (around 20-25% more) than the ChannelMaster. I would think, all other things being equal, my signal with this big dish should be a lot better than what I am getting, and certainly should be a lot more than what I can get with a smaller dish.

I've checked everything I can think of. No obstructions, good cables, good LNB that works just fine when attached to a different dish. As far as I can tell, it's not bent or warped (how could it be, molded fiberglass would more likely be cracked and broken than bent)

Before I pull the rest of my hair out, any suggestions?

 

[Pepper]

ChannelMaster (right) gets consistently lower signal than the SuperDish right next to it.

 

[primestar31]

View attachment 174937
ChannelMaster (right) gets consistently lower signal than the SuperDish right next to it.

Ok, LOOK at the lnb feed. You have it strapped by the feedhorn, YET, it should be strapped closer to the lnb where the GROOVES are... So, move the face of it closer to the dish, and put the groove area in the saddle. I circled it in red below

 

[Pepper]

Ok, LOOK at the lnb feed. You have it strapped by the feedhorn, YET, it should be strapped closer to the lnb where the GROOVES are... So, move the face of it closer to the dish, and put the groove area in the saddle. I circled it in red below
View attachment 174938

I do believe I have tried that and the position in that photo is where it gets the best signal. It's also where it actually fits. The top piece to hold it in place has always been missing, thus the zip-ties, but it fits exactly in that spot based on the size of the bottom piece which it sits on.

I will definitely fiddle with it some more though. I will also disassemble it all and take some better close-up pictures from multiple angles.

 

[primestar31]

I do believe I have tried that and the position in that photo is where it gets the best signal. It's also where it actually fits. The top piece to hold it in place has always been missing, thus the zip-ties, but it fits exactly in that spot based on the size of the bottom piece which it sits on.

I will definitely fiddle with it some more though. I will also disassemble it all and take some better close-up pictures from multiple angles.

Perhaps I'm mis-remembering now. It's been many years. Anyway, here's the manual, that should help.

 

[Pepper]

Perhaps I'm mis-remembering now. It's been many years. Anyway, here's the manual, that should help.

Thanks for that. According to Figure 3.0 "Feed Assembly" it looks like I have it assembled correctly. Parts 11, 12, 13 are missing, replaced with zip-ties

 

[primestar31]

Thanks for that. According to Figure 3.0 "Feed Assembly" it looks like I have it assembled correctly. Parts 11, 12, 13 are missing, replaced with zip-ties

I'm thinking the wireties aren't enough support for that long and heavy feed, That's maybe allowing the whole thing to tilt slightly down in the back from the weight, which would screw with the focal point/face lifting slightly. Even just a hair might be enough to put the signal down 25%.

Get a piece of aluminum strapping, and make a new top part of the clamp, and clamp it down tight. Aluminum should be stronger, yet soft enough to hacksaw and files, etc whatever you need to make it work well. Or a U clamp that fits. Short of that, you could use a piece of plywood and cut it to fit the reverse of the saddle using a hole saw with your drill.

 

[arlo]

A few things not mentioned that may help. I helped a Brit get his same dish setup. It took a bit but eventually he "got it".
The LNBF. How rigid is it on the dish? Is the "look angle" correct? The LNBF needs to be set to see signals reflected 22.5 degrees off of the face of the dish. More on that if you need info.
Being an offset dish. You may be better off skewing it more like your other dishes. Or not.
LNBF placement rigidity is super important. As is aiming it so the throat is pointed the right place on the dish. A little up, down, right, left will kill signal. In and out like focusing a fixed focus camera.

 

[arlo]

 

[Pepper]

A few things not mentioned that may help. I helped a Brit get his same dish setup. It took a bit but eventually he "got it".
The LNBF. How rigid is it on the dish? Is the "look angle" correct? The LNBF needs to be set to see signals reflected 22.5 degrees off of the face of the dish. More on that if you need info.
Being an offset dish. You may be better off skewing it more like your other dishes. Or not.
LNBF placement rigidity is super important. As is aiming it so the throat is pointed the right place on the dish. A little up, down, right, left will kill signal. In and out like focusing a fixed focus camera.

Is it always 22.6 degrees, is that part of the math that makes these things work, or is the exact angle determined by the shape and size of the particular dish? None of my other more oval style dishes seem to be anywhere near that much of an angle.

Skew is not an option with this dish design, other than twisting the LNB. Elevation and azimuth is all it can handle. I suspect my issue has a lot to do with weight as primestar31 suggested and getting it mounted exactly right and tight enough to stay there. I'm also going to disassemble the thing and clean it, maybe some bugs have got in there and built a nest or something.

 

[a33]

Is it always 22.6 degrees, is that part of the math that makes these things work, or is the exact angle determined by the shape and size of the particular dish? None of my other more oval style dishes seem to be anywhere near that much of an angle.

That 22.6 is typical for the Channel Master offset dishes. Other dishes may have other offset angles.

Is the vertical angle of your dish face indeed: Satellite elevation minus 22.6 offset angle now?

When the feedhorn is at the focal point, you should have reception at that elevation
RimaNTSS has put the CM offset dishes geometry in this picture:

CMHolder-Placement hosted at ImgBB

Image CMHolder-Placement in Rimantss's images album

imgbb.com

Personally, I would aim a bit higher than the G-spot in the picture: at the deepest point.
But having the feedhorn at the focal point is more important than using an exact aiming point, if I'm informed correctly.

Greetz,
A33

 

[arlo]

Look. The CM/Andrews/Raven dishes are basically the same animal. No need to dive deep, just accept that the look angle is 22.6 degrees. If you're a tenth or so off either way. No biggie.
Is that thing flopped on the ground and propped up with your brother's boots? Let's see the back of it.
Does it even have a mounting plate and pole mount bolted to the back?

I keep harping to just get a digital angle gauge. The little Klein cubes to the sky's the limit. Don't wast a penny on an inclinometer in 2024 on up.

Look at the elevation scale on your dishes that do work well.
If you lay a straight edge across the dish faces from the top center to the lnbf mounting arm. With a little math you can figure out their look angle. Better if you temporarily zero the skew so that the straight edge lays vertical.

From the Brit dude with his CM dish who uses a horizon to horizon mount. Which add its own skew as it travels the sat. arc.
Once he setup the dish at zenith. Set the elevation (latitude) angle using the dish face for reference minus the dish look angle. Let's say 42.5 degrees minus 22.5 degrees. Which ended up tilting the dish down towards the dirt.
His closest true South satellite was found fast. I mean Fast!
For your setup with fixed dishes we won't discuss dish declination. Latitude minus look angle will do.
Fine?

But in my opinion I will still stick with you should set the lnbf skew at 0 degrees relative to the dish face at 0 degrees tilt CW/CCW looking at the front side.
And add skew only by rotating the whole dish just like your others.

Then. Aim your LNBF to snag a signal. You should not have to tilt the dish elevation angle much at all.
If you find you need to. Then you've screwed up the look angle.

I'm practical. Maybe a bit "out there". Imagine you have two coffee can lids laid exactly on top of each other.
The one on the bottom being the dish face and the top lid being how the dish is "illuminated" by the LNBF.
If you slightly move the top lid up so that you see the bottom of the bottom lid, or move the top lid down so you see the top of the lid on the table top. There's your look angle Mr.
You've seen the solar eclipse. That moment when you see the suns corona perfectly for a minute.
That would be your LNBF focus spot in an ideal world. An ideal world may only be attainable using an LNBF with conical scalar for your setup. So you can only do what you can.Your fixed dish/lnbf's are designed as a pair to work proper.

Other than that. I need more of what's under those coffee can lids. Good luck.

 

[Pepper]

Well. Issues solved, or at least a whole lot better now!

And despite causing myself some embarrassment, I will detail what the fixes are.

First, I disassembled the feedhorn from the LNB and inspected it. There was some dirt built up inside. I thoroughly cleaned all of this and reassembled. This didn't seem to improve things any.

Next, I got the bright idea to try one of my cheap Chinese universal LNBFs. It fits the mount, and is much less heavy so it's not trying to fall off. Also the throat of the feedhorn is not nearly as long and a little wider, which translates to a lot more tolerance to having exactly the straight look angle. I was able to adjust it for best signal and it's actually pointing slightly downward. This improved the signal around 5% or so, but for the size of this antenna I still didn't feel like that was enough improvement.

Finally, I got to the literal root of the problem. I've been using a satellite finder app on my phone which does an AR-like view of the southern sky showing me where the satellites are supposed to be. Instead of relying on this, I decided to actually measure the angles more accurately and what did I find but a heavily leaf covered tree limb in the way. So I got out the post hole digger and moved the whole thing about four feet forward and planted it. Now my signal is significantly better, was able to tune it in on Alex Jones' ridiculously weak transponder quite quickly. He, and the national and Montana PBS are coming in quite well now. I'm still not seeing the Family Radio mux (11993V1075) however.

As measured by my receiver for that specific weak transponder, I was previously getting around signal=65, quality=60, now it is a steady signal=77, quality=70.

Thanks for all the help and suggestions! Especially all the stuff about theoretical and pictures and the angles.