Better signal with or without angled waveguides?

[Inno]

I am under the impression that the 90° angled waveguides common on most C-Band dishes are in place simply to make the feed/lnb take up less width so you can get a smaller nose cone on the dish. I thought I'd read somewhere that you can increase your signal a few Db by omitting them and attaching the LNB sticking straight out the side. Is this correct? Is the gain enough to offset the signal being blocked by the LNB sticking so far out? Is this true of C band and Ku when using a BUD?
And while we're on the topic of maximizing signal strength, is there anything wrong with using a buttonhook feed for Ku as opposed to the 3-4 post mounting method?

 

[turbosat]

I read somewhere a few days ago, about those angled waveguides, I believe this source said you can lose 3db from using one, and they recommended placing the lnb on the feedhorn without it, to increase the signal you're getting. On a smaller dish that would make a nice difference.
As far as the buttonhook feed vs the other type, I think most of us like the 4-leg approach because they are easier to tweak/position to the face of the dish. The legs can be adjusted/bent if necessary to get the proper f/d and 'look-angle'.

 

[gabshere]

if you can try both ways it would be best ( but from what i've read its 3-5 db gain)
the main feature for the angle waveguides is so it will present a smaller area and a cover can be installed over the feedhorn. If you look at some commercial feedhorns most are built so they don't need this angle waveguide.

i think the dish size usually makes up for any loss from blockage with the lnb sticking out. Just puts it out in the weather/elements if not covered.

And while we're on the topic of maximizing signal strength, is there anything wrong with using a buttonhook feed for Ku as opposed to the 3-4 post mounting method?

i think another reason for most c-banders prefering the 3-4 leg feed support over the buttonhook is the older buttonhooks commonly developed sag and put it out of focus

 

[Inno]

Right, I hadn't thought of the sag issue. As far as f/d mine is adjustable over a very wide range but when I put on a C/Ku feed that'll increase the weight. I know that the buttonhook on my Orbitron is made of steel and so is the mount it uses to secure it to the dish so the chance of sag will be minimal but certainly something to watch for.
Even though it's a 10' dish I will leave the waveguides off to maximize signal 'cause I'm going to start with the old LNBs I have currently. I think they are both Nor Sat units so they should be good even if there are more modern ones to use.

 

[gabshere]

i don't think sag will be an issue with most of the users here unless its from climbing on the dish all the time trying to peak it again lol

but for the normal user (who probably never set up the dish or even work on it) after setting a few years out in the weather, sag could degrade the signal. someone here also mentioned using guide wires to help control the sag and help center the buttonhook mount.

 

[14karat]

Talking about the buttonhook, I saw somewhere in the forum where someone used 3 or 4 guy-wires (placed similar to the pole mounts).
That would eliminate the sag as well as windflop in the buttonhook.
AND using turnbuckles on the guys gives a pretty neat way of aligning the f/h...

 

[turbosat]

from the geo-orbit page

I found that quote, about the gain from leaving off the waveguide elbows, it was from the geo-orbit page on installation and tracking the arc. Quote:
Leave off the elbows, if you want,
and let the LNB(s) stick out to the side - you will gain three
dB if you do. That's found in the section about setting the scalar and f/d.

 

[1captain]

I found that quote, about the gain from leaving off the waveguide elbows, it was from the geo-orbit page on installation and tracking the arc. Quote:
Leave off the elbows, if you want,
and let the LNB(s) stick out to the side - you will gain three
dB if you do. That's found in the section about setting the scalar and f/d.

Hi Turbo, that 3db is alot of gain, now with what you read that is C-band right? an if you louse the ku 90 degree wave guide it has to be more than 3db due to the high freq. of 12ghz rater than 4ghz.

 

[turbosat]

1capt I think you're right about the higher freq/gain. I don't have one working to play around with, but a corotor or something like it would be good to test that idea out on. I got 2 broken ones lol, but the guts are out of them so they wouldn't work for ku at all.

 

[Inno]

If I get some cement poured this fall I'll be able to test the theory. If not it'll have to wait 'till spring.

 

[truckracer]

I have never ran the elbow on my waveguide. I read about the losses before I ever put up my dish.

 

[AudioFox]

If the -3dB figure is correct, it would be prudent to note that +3dB is approximately equivalent to doubling the signal, very good since it would be doubling the weak signal received from space, before it is amplified by the LNB. I've left the elbows off of all of my previous BUD setups with good results, the weather problem isn't much of an issue, especially since the feed covers on my dishes have all been large enough to leave them on.

 

[voomvoom]

I've found that you/I get a better picture without using them, but you can't get the weather cover over it without modifications? So, it comes down to either you accept a lesser signal and use the weather cover, or you say to heck with the cover and go for all the signal you can get? Or, you can modify the cover and use both? I'm sure you can get more than an adequate signal with it, but different people look at life differently. I take mine out, and go without the weather cover, but I like to squeeze in as much signal as possible.

 

[Inno]

I'd say that if you're using compression fittings which tend to keep most if not all the moisture out of the connection, in most cases it'll go for years like that. It's the coax connector that is the weak point, the LNBs are all sealed pretty well. So bring on the signal!!!! I don't really care what it looks like.

 

[turbosat]

hacksaw

I 'modified' one lnb cover with a hacksaw once, hehe, looked funny and didn't keep out all the bugs but it was good for protection from the rain.

 

[Inno]

I find that the covers only serve as a nice dry home for bugs etc. so in the interest of not giving the bugs a home, I'm definitely leaving mine off now!!!!

 

[truckracer]

I don't run any weather buckets over my lnbs/feedhorn.
No problems ever with moisture. I have heard some people claim the lnbs run cooler too.
My lnbs are white in color which reflects solar heat better than the black bucket. So I am inclined to believe it is better not to use a cover as long as you use proper outdoor connectors w/ o-rings and coax seal. Your gaskets between your lnbs and feedhorn are properly sealed and secure.