Leave off the Elbows ???

[Greg Mueller]

While looking for C-Band info I came across this page. The author suggest leaving off the elbows on the Co-rotor for added gain. Does that sound right?


"......Do not overtighten bolts, flanges will crack. 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. If......"

http://www.geo-orbit.org/sizepgs/tuningp4.html#anchor677238

 

[dfergie]

Might be worth a try...

 

[Shawn95GT]

I might give that a shot for my Ku LNB if the feedhorn cover will fit. My Ku performance has been pretty ugly.

 

[WyrTwister]

For what ever it may or may not be worth , I am not using elbos on my C Bans LNB .

Wyr

While looking for C-Band info I came across this page. The author suggest leaving off the elbows on the Co-rotor for added gain. Does that sound right?


"......Do not overtighten bolts, flanges will crack. 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. If......"

http://www.geo-orbit.org/sizepgs/tuningp4.html#anchor677238

 

[voomvoom]

For what ever it may or may not be worth , I am not using elbos on my C Bans LNB .

Wyr

I don't use the elbo's either. I also don't use the cover. And to me it makes sense because every turn is an obstacle. The less obstacles the better. But, I don't know if will make that much of a difference. So it may be a moot point.

Al

 

[AntAltMike]

I would expect the improvement to be less than half a dB, but what the heck, people used to spend a lot of money to "improve" their LNB noise temperature from 25 degrees or twenty down to 17 degrees, yet if you bother do to the noise temp to dB conversion, you were only improving the C/N ratio by a tenth of a dB or so.

FWIW, the premium C-band LNBs that are used for digital reception typically have noise tmperatures of 25 degrees, but the companies paying a few hundred dollars for them are not clamoring for lower noise temperatures.

As I recall, three dB is the thoeretical C/N improvement of circular waves if one uses a feedhorn and LNB pair designed exclusively for circular wave reception versus an LNB with a linear probe attached to a feedhorn with a teflon plate kludged into it.

I haven't used feedhorn covers in years. They were only good for supporting bird's nests and bees nests.

 

[bnaivar]

I read somewhere that the elbows can cause SWRs in the feed. I've tried it with and without and never really saw a difference.

 

[Shawn95GT]

FWIW, I went out to see if I culd get away with taking the elbows off and found that I could not. The CalAmp Feedhorn has a 2-bolt flange where the Ku elbow attaches to the feedhorn. I'd have to get a different waveguide adaptor to eliminate the elbow. I think I'll just leave it and work on optimizing what I've got.

I did notice that my C band LNB's fitting had been leaking at it's connector and it now corroded black inside the connector. It still works fine but I replaced the cable end and I'm going to do some weatherproofing / get my feedhorn cover back in action.

 

[determined]

I think AntAltMike is right. I still use a cover, hey, the wasps need a home too, and they contribute to keeping my agility when I have to remove it.

 

[gizzer777]

Same here

While looking for C-Band info I came across this page. The author suggest leaving off the elbows on the Co-rotor for added gain. Does that sound right?


"......Do not overtighten bolts, flanges will crack. 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. If......"

http://www.geo-orbit.org/sizepgs/tuningp4.html#anchor677238

I remember being told that about 10 yrs ago...Have not had elbows for at least that long and my quality is excellent.
Jeff

 

[ats7627]

I would expect the improvement to be less than half a dB, but what the heck, people used to spend a lot of money to "improve" their LNB noise temperature from 25 degrees or twenty down to 17 degrees, yet if you bother do to the noise temp to dB conversion, you were only improving the C/N ratio by a tenth of a dB or so.

Remember Gary Cubetta of Satellite City TV and his "Super Ice" LNB?