Measuring Dish Size / Feedhorn Cover Is it needed?

[Davage]

Combining 2 questions into 1 post.

What is the proper method of measuring a C-Band dish size? I took a tape measure to my dish last night, and it appears to be about 7.5 feet. Is measuring straight across the dish the accurate method of determining dish size, or is there a formula involved to compensate for the curvature of the dish?

Is a FeedHorn cover really needed? Most LNBs and feedhorns are waterproof, are they not? When I took the dish down from it's previous home a couple weeks ago, the wasps had built a HUGE nest inside the feedhorn cover. I'm planning on just tossing the feedhorn cover out and leaving the LNB and feedhorn exposed to the elements to avoide another massive wasp nest.

 

[gabshere]

yes thats the correct way to measure it all the way across the only formula involved would be for checking the focal distance.

the cover does a few things if properly installed , like keeping most of the critters out and wasp , plus most would provide a 95% mosture barrier and keep the equipment inside clean and like new , out of the elements

notice all those without covers usually have a coax waterproofing material ( if not the coax connection is out soon).

 

[Davage]

In my area, wasps are a constant battle. They like to build nests wherever they can find a place. This cover in the past hasn't kept the pests out, so I'm simply going to leave it off and deal with any element issues if they come up with the electronics. New LNBs are around $25 these days. A can of Wasp Spray can be from $9 to $19 in my area, so either way something is going to eventually cost me some money I have an allergy to bee/wasp stings, so I'd rather replace an LNB instead of having to deal with wasps.

 

[Anole]

any chance this could work ?

There's a type of foaming insulation you can get at Home Depot for sealing where a pipe goes through your foundation.
The stuff sprays out, foams up, fills cracks, and turns hard , as I recall.

Let's see, how could you do this with the least trouble?
What about some heavy plastic wrap covering the front of the LNB and wrapped around the rear of it, too?
Saran Wrap might be better replaced with a heavy plastic - even a plastic trash bag.
A lot of plastic bags are designed to break down in UV , so you'd want to avoid that material.
That would keep the front of the LNB clean, and the foam out of the rear of it.

You might need to punch a hole in the plastic wrap and cover it with gauze or some sort of mesh for drainage or breathing.
There is plastic screen-wire mesh - you could get a postage stamp sized sample.

Then, fit a bucket (LNB cover) with proper mounting hardware.
Test the foam insulation, to get familiar with how it works and how much it expands.
Squirt a shot of foam into each opening, around all cables, etc.
Maybe you could use tape as a masking material, then rip it off once you'd foamed the gaps?

I've always wondered if the LNB cover, properly filled with the expanding foam, wouldn't be a good thermal insulator, both for summer and winter work?

Someone with the actual items would have to evaluate if this is a workable idea.
I just present it as a starting point.

 

[starman345]

I never was a fan of feedhorn covers, they cause more problems than they prevent. The heat inside one of those things is pretty intense in the summer, not a good thing for an lnb...also, they catch the wind and add to the wobble of the dish, pretty annoying if you like to watch ku. If you fill your coax fittings with di-electric grease you will be covered from water ingress and also the biggest problem which is condensation, if the fittings are filled with grease there is nowhere for condensation to take place. My 10 footer has been sitting out back without a cover for 17 years now.....and besides I think it looks better
Something I've noticed over the years, is that I've never seen a feed cover on a dish at a cable tv dish farm. Maybe thats just around here....anyone else noticed that?

 

[Diamond Jim]

In my area, wasps are a constant battle. They like to build nests wherever they can find a place.

What I do is get some Raid Wasp and Hornet spray. If there are any in the feed horn I give it a blast to get their attention, wait for the survivors to clear out, then I clean it out with a rag or paper towel the best I can, then respray the insides again plus around the rim a bit. Once the smell of that stuff get inside the horn that should keep them from coming back. At least it works for me. Good luck.

 

[Diamond Jim]

Let's see, how could you do this with the least trouble? Saran Wrap might be better replaced with a heavy plastic - even a plastic trash bag.

Saran Wrap............that's a good idea, wish you would have told me years ago. I use the white semi plastic bags that you get at the grocery store, Wal mart, ect and I use the plastic ties to secure it. I put the bag on around October 1st and by the end of March early April it has practically rotted down to nothing, the ties are in perfect condition. Saran Wrap.........damn, I will keep that in mind come this fall.

 

[Anole]

I use the white semi plastic bags that you get at the grocery store, Wal mart, ect and I use the plastic ties to secure it.
I put the bag on around October 1st and by the end of March early April it has practically rotted down to nothing, the ties are in perfect condition.

Those plastics and frankly the trash bags, are designed to turn to dust in the land fills.
There's a heavy industrial shrink wrap used on pallets of food delivered to grocery stores.
But, those might need to be recyclable, too.
What I was really thinking might work, is the heavy duty freezer bags.

If we have a materials specialist on the forum, maybe he could recommend something better.
Tupperware? Two bowls facing each other, held together at the lip, by . . . ?


And if you just want to go naked, maybe there is some sort of sealant you could use on the whole thing.
Suitable masking might be needed, though.

 

[Diamond Jim]

There's a heavy industrial shrink wrap used on pallets of food delivered to grocery stores.

I work part time in the warehouse at a major midwest electronic/appliance store and we have tons of that rolled plastic. It's very strong because they will pile a huge amount of small electronics on a pallet, wrap it in this stuff, put it in a semi trailer and ship it for miles. When we get it, it's always in tact. I will check into that.

 

[Anole]

Okay, Mr. Wizard . . .

That's exactly the stuff I was thinking about.
Get a piece this week, and arrange somewhere to put it out in the sun and see how it holds up through the summer (higher UV months).
As a control, put out a sample of your usual plastic bag, a trash bag, a freezer bag, and some Saran Wrap.
You can become our expert on materials!


Oh, and in my comment above about a sealant, I meant something like a varnish or verithane or some such paint-on or spray-on material.
If the coating was thin, I don't think its dielectric constant would have any affect on the scaler.
I've painted my front door with outdoor clear, with extra UV inhibitors, so it'd last 5-8 years in direct sun.
Just thinkin' out loud...

 

[linuxman]

If you have been reading my thread LNBs - Which of these is best?, I have settled on the Norsat LNB which causes the feed-horn cover to no longer fit. I have it on right now with two screws and duct tape. It is kind of cocked.

I followed this thread, and see all the good ideas. Is just sealing all the connectors sufficient. There are gaskets between the LNBs and Co-Rotor. So is there anything else needed.

I am thinking about just leaving mine out to exposure to the elements.

Thanks,

Fred