$5 C band dish

[Alec]

I'd found this 5.5' dish in a scrap bin, restored it best as possible. Set it up in place of my Ku dish and tried several Ku lnbf (invacom included) , no luck. Is the mesh on a C band dish compatible with Ku ? The mesh is real fine, common pencil lead will barely pass through it. The 36" dish has been working fine. Thanks guys

 

[charper1]

Are you sure you have the correct focal point?

 

[charper1]

Are you sure you have the correct focal point? Have you tried a CorotorII feedhorn with C/Ku LNBs?

 

[rkrenicki]

is it just me, or is the curve of that dish... not that good? seems like it has alot of screws in it, and it just does not have a smooth curve look to it... in which case, the focus is all screwed up..

if not, then its the way the photo looks, I guess.

 

[PSB]

I agree, looks like it is being used as an offset dish, its going to have to be used as designed, prime focus.

 

[rkrenicki]

looks prime focus to me.. just one of those stupid center supports, instead of the tripod ones.

then again, it is in no way angled correctly, or have an lnb on it in the photo, but the dish itself just does not look smooth.

You say you restored it, did that entail flatening out parts? because that is going to cause problems if it is not perfect.

 

[Alec]

Focal Point

Thanks guys, first, will a mesh dish suport Ku band ? Im ataching a drawing on my impression of how to locate focal point, the dish diid not have lnb suport, had to fabricate, tried numerous attempts to locate FP. Didnt ever get a flicker of Quality on the Pansat 2700a. Sorry to bother, but interested in input. Alec

 

[PSB]

Nice sketch! The below is a great read on this topic .....

http://www.mlesat.com/antennas.html

 

[charper1]

Yes, mesh will do KU very well depending on the size of the holes.

 

[rkrenicki]

sounds like your mesh is ok for Ku, I would be more concerned about the overall shape of the dish.. the tolerances for the dish itself are pretty tight (like 1/16th of an inch).. and no, this stuff is never a bother, thats why we are here

 

[Alec]

ugg, I tried for many hours to locate siginal, not having original lnbf suports hinders finding FP. Tried for many hours to locate Sig on Pansat 2700a , but not ever a flicker of a red siginal. Dish dosent seem to be so badly out of shape as to not recieve a red siginal. Had to fab a lnb support and guess at FP location. But Oginal Q was does C band dish suport Ku, yea, you guys are comming back that it does. Ans, my question, ............ugg, to locate FP after many hours spent aready, many diff FP attempts made. Back to field trials again, thanks , Alec

 

[n4bbq]

ugg, I tried for many hours to locate siginal, not having original lnbf suports hinders finding FP.

What you need is an analog receiver to tweak this dish back to life. I just picked up another one on eBay for $4.21! If you had an analog receiver and a C-Band LNB, you could find your focal point within 10 minutes if you have someone to move the dish around with you stand in front and move the LNB around. I cannot stress how easy it is to find satellites with an analog receiver.

The focal point of the dish you are using will be directly in front of the center of the dish. Below is a calculator:

http://www.csgnetwork.com/antennaparaboliccalc.html

 

[caddata]

It appears that you have not located the focal point accurately. The formula for focal length is F= 2x dish dia./16x dish depth. Measure the dish diameter. Measure the dish depth by placing a straight edge (a 2x4 for example) across the rim of the dish and measure, along the dish's axis from the 2x4 to the bottom of the dish. Plug these dimensions into the formula and you'll have the exact focal length. Fabricate a tripod mount, from 3 equal length pieces of 1/2" thinwall conduit, that attaches to the rim of the dish on one end and the scaler ring of your feedhorn on the other end. The focal point should be about 0.250" inside the mouth of the feedhorn.

 

[Alec]

Great input guys, I may be able to locate an analog reciever down the road from me. Thanks !!

 

[ken2400]

Try this.

If you have a DTV/Dish LNBF try getting 91, 110 or 119. Nice bright birds to start with. If you do not have that type of LNBF then pick say AMC 3 11822 H 5700 that is a nice brite TP to hit.

Good luck and use your other dish to guide you in pointing the big one right to left.

Great input guys, I may be able to locate an analog reciever down the road from me. Thanks !!

 

[Alec]

Success ! The links you guys provided on Focal Point were great ! They got me darn close ! I scraped the lnb support Id made and made a fully adjustable one, telescopic and fully adjustable angles on both ends. After initial setting of lnb support, 1 cm adjustment and I was right on. The FP was much closer to the dish than Id origanaly thought. The 170cm dish doesnt seem to have a greater improvement on the already stronger signals. helps mostly with weaker signals. Ive always been interested in NBC on AMC 4, like watching Jay Leno. The signal was usualy 0% durring the day, but after dish swap, was as high as 20%. Signal seems to be better after sun goes down. TPs on IA5 seem to come in a bit better. $5 spent on this dish seems to be OK, but not sure about spending $500. Also, Invacom I believe makes a statement about the difference in the single and dual output models of thier .3dB lnbf. Dual output model should have better signal with lager dish. Im using the single .3, not sure about going to dual Invacom right now, checking out dual C/Ku lnbf. Thanks guys for the links to FP info !!!!!!! Alec ...............PS, if the local cable profider wasnt so poor, I wouldnt have started all this.

 

[Alec]

Am trying to upload photo of lnb suport........

 

[PSB]

Very nice work!

 

[Alec]

You guys made the difference on this one, my thanks !!!!

 

[lilyarbie]

possiblity of solar interference during the day???

You said something about the signal being stronger at night than during the day. It could possibly be solar interference with the signal during the day since the sun is right behind the satellite you're pointing at during the day. I'm not certain, but this idea does make sense.