Anyone interested in an 8ft offset dish?

[Cham]

Nice to have heavy equipment around when (aquiring) a large dish!
Might drop you a note if planning to head down that way with the truck... It's not that far.
-C.

 

[Cham]

Might as well resurrect an old thread again rather than start a new one...

Went for a road trip yesterday, almost exactly one degree of latitude south, and ended up with a loaded truck for the way home. Met Mr. FaT Air and completed a deal with him; small dish for a larger one. Put on a few miles but was certainly worth it, the old Chevy hasn't been on such a long trip for quite a while. Glad it held together!
Was a nice warm day, maybe 90ish with about an 82 degree dew point... Perfect weather to play with large heavy satellite equipment. FaT Air and I had to put our backs into it to get the big dish loaded onto the truck. Mount likely weighs as much as the dish!
Now I have to wait to unload it, my front-end loader tractor is away at the tractor hospital getting some repairs done... Hope to get it back this week. I want to give the dish a good cleaning and store it indoors until I can get a mount welded up for it, and a base poured (once I figure out where it will go!

Thanks to FaT Air! Enjoyed the tip and the visit, he's a great Satellite Guy!

 

[FaT Air]

Think there's some 'out of footprint' signals you'll get with its (estimated/ballpark) 12db more gain than a 1 meter.
Nice visiting with you, and I will be putting our trade into service asap. (One port on the switch is available for testing)
All that heat and humidity turned into some worrisome weather later in the early evening. Glad it held off till then.
First came wild winds, then the temp dropped from near 90 to 70 in about 10 minutes, then the rain. (70 felt good then) Tried to get an audio recording of the continuous rumble after the rain passed. It was awesome. But not the recording.

 

[Cham]

Yes glad to have missed the weather!
Loader tractor might be finished tomorrow so I can unload the dish. Think I have located a pole (mast), but in a 20ft length at the auger manufacturer nearby. I think it is heavy enough but will have to get them to cut off 6 ft or so for me!
They didn't give me a price yet though...

 

[FaT Air]

Had a bit of time before making something to eat. And the 'farm' area is shaded then. Mounted on a new temporary base of crossed 2x3's beside the 1m. Aimed it at 99 and Voilà! A little peaking and it's working almost as well as the 1m when it's peaked @ 99w(from notes). (1m is off a bit now but haven't spent time on it)
Now pondering how to replace the 30 inch on the BUD with it. Would have been super easy if the bolt pattern were the same. (yeah - right) Need to fab some metal.

 

[PopcornNMore]

Nice dish! So, when are you delivering it to Pennsylvania?

 

[N6BY]

Think there's some 'out of footprint' signals you'll get with its (estimated/ballpark) 12db more gain than a 1 meter...

I'm seeing quite a few more KU-Band transponders on my solid dish which is about the same size. Feed hunting is far more productive on a dish that big.

 

[Cham]

Took a long time, but since hearing of FaT Air's passing, thought I should get cracking on this project and get this beautiful dish he gave me up and running. Stopped by the local machine shop and found a 6' schedule 40 pipe (6.64" OD and about 3/8 wall thickness) should do. I had the machine shop cut me three 1/4" steel gussetts, and I found some 1/2" X 24" pieces to use for a footing. Spent much of the morning and part of the afternoon in my shop with Mr Lincoln (welder) and went through about 1/2 of a box of welding rods. Cleaned it all up and did some painting... now all it needs is the dish! Winds here are about 35mph today so I don't want to bring the dish over (paint needs to dry anyway).

 

[Cham]

Wind calmed down a bit this evening so I brought over the dish and attached to the mast. It seems bigger than it is... but it's still inside.
Forgot to bring out the camera but took a capture from security cam; from the back in IR. Note the combine in background for size comparison. LNB arm(s) are laying beside.Cobweb messes up the image a bit...

 

[Cham]

Have the dish installed and working!
And it works great on G13 @ 127W C-band. Now I don't have to swing the 10 footer all the way west to watch the NASA channel(s)! Might play a bit later today with a dual-band LNBF and see how Ku works on that sat, maybe there is some FTA on that one?
This is a temporary setup, not sure if this will be a permemant location, so I mounted it on railroad ties and buried them. Dish is really solid there should be little risk of it blowing over etc. I have had another 8' dish mounted on ties for several years and it hasn't budged since it settled in after maybe a couple of months. For sone reason frost doesn't seem to bother it either.
Some pics:

 

[Cham]

Dish is still working great, swapped out the old DRO LNBF I was using, one side decided to stop working. Installed a new C2PLL from Ti and I am getting almost 3dB better s/n on the NASA TP and getting the other channels (on this satellite) much better now. Noted the exact placement of the conical scaler ring is critical to tuning, as it can exactly filter out specific TPs with less than a millimeter movement toward or away from the feed point. The sweet spot brings up all the TPs 1-3dB over not having the scaler at all. Really cool to see this.
When setting up the feed point I put the LNBF feedhorn in almost the exact position the previous Ku BUC was installed at, measuring in from the sides of the scaler to the end of the lip of the actual feedhorn to find the original position on the feed arm "platform". Then I built the "custom" bracket (green paint in the picture) and used a C-band LNBF holder to hold the feed opening at the same position as the previous Ku feed horn. Then the dish was moved into it's current position in the dish farm.

Eyeballing the dish position I was within a half a degree of the satellite, so fine tuned it with my "watch repair tool kit" (consists of 1"-2" combination wrenches, of which the 1 1/2" wrench was used) to set the az/el for maximum signals. Then back to the LNBF, moving it towards the dish about 1/2" peaked the signals. Then I added the scaler ring and again peaked the average signals by moving the scaler towards and away from the reflector on the LNBF barrel. Guess I set the skew somewhere before and during this process. After installing the scaler, moving the LNBF back and fourth in it'a clamp only lowered the signals. I think it is in it's sweet spot...

Now I am thinking I need to protect the LNBF from moisture incursion due to it's orientation... It is designed for a prime focus dish so it is always facing downward to look at the reflector. Using this offset dish it is looking "upward" at the reflector, which turns the feedhorn into a fine waterproof vessel. Looked through some coffee can lids and anything else I could find kicking around, nothing I have really fits well. Maybe some of you Mini-Budders have run into this issue and found something that works? Until then some cellephane and electrical tape will have to do...

 

[Titanium]

A few use margarine (or cream, hot chocolate, etc.) covers. The cover could fit over any one of the rings in the conical scalar. In my conical experimentation, water collecting in the bottom of the rings can change the scalar performance. Put some Rain-X or Rain Shield on the cover to quickly bead the water. Streaming rain water on the cover surface will quickly knock the signals down (or out).

Even with a cover, condensation will possibly still collect in the cavity. If a fixed dish, drill a small drain hole in the bottom of the back of the thoat. If motorized, drill several holes around the edge to allow drainage in multiple places on the arc.

 

[danristheman]

Go to store buy nestle Toll house cookie tub about 5 bucks use the lid for the scaler. Eat cookies and give some to wife to shut her up for a while. Give her chocolate put her in good mood. Lid fits perfect around the scaler I use 2 of them.

 

[Cham]

Was hoping the space between the scaler and the LNBF would allow sufficient air movement to minimize condensation... but maybe not. Will confiscate any margarine container lids as they are available and fit them into one of the steps in the conical scaler and see how that works. Will have to check for attenuation as well!
Dan the Wife is diabetic so she won't eat the cookies. Guess I'll have to eat them. Oh well... Oh, and part of her education background is in electrical engineering... so no issues with electronics-related hobbies here!

 

[Cham]

Found an almost-empty mararine container that has donated it's lid... Fits perfectly and covers the whole scaler opening!
Now for some peanut butter and jelly sandwiches (have to finish the margarine that was in the container!).

 

[Titanium]

Was hoping the space between the scaler and the LNBF would allow sufficient air movement to minimize condensation... but maybe not.

Depends on your weather conditions. No condensation in Northern California in the summer. In the winter the condensation will collect in offset mounted (inclined) feedhorns. I must drill drains on my offset feedhorns. Of course, when mounting on a prime focus dish, the downward slant effectively drains the feedhorn cavity.

With a cap mounted on the conical rings, you should be able to get away with removing the feedhorn cap and pick-up a little additional signal.

 

[Cham]

I am afraid of what will happen in colder weather (near freezing) where any drain can fill up and freeze, leaving moisture to build up inside and go through freeze-thaw cycles. The small area inside a Ku feedhorn doesn't seem to do this, so maybe with the C-band scaler covered it will not catch much moisure (condensate). Summers here are like your (Brian's) California winter with lots of humidity and heavy dew overnight. Winters here though can be damp but also sub-zero, so any moisture that collects will have to melt and/or sublime, or evaporate if temperatures reach above the freezing point. A bit of sunshine peridically will help too.
Sprayed a bit of "Pledge" on the outward-facing surface of the margarine lid to help repel the water. Seems to be working. Been drizzling on and off today and reception is similar to yesterday. Signals are really stable from this dish assembly. Now I need to find a 12-footer designed as well as this one...

 

[Ali Erfani]

What an awesome reflector, if i had enough space i would buy it.

 

[Cham]

Think I am going to keep it!