Condensation is going to last longer inside that plastic box, so it may actually speed up corrosion. On the other hand, it would protect the dielectric grease from drying out / washing away sooner from the sun and rain.
Best Plastics, Composites, Rubber for structural antenna parts
Just a warning note about using ABS for structural parts that I've mentioned many times before - hopefully what you're planning to use is the thick walled stuff that has little or no flex. If you go to Rona or Lowe's or Home Depot and shake a 10 foot ABS pipe like a sword it flexes a lot. 
It seems to be rigid, but its not. If you shake a length of PVC like that it will seem like a wet noodle, so avoid using PVC for structural use either, except when recommended in build plans.
From experience I'm clarifying that ABS should never be used as a pole or mast, and it should be carefully considered if you're thinking of using it as a horizontal boom of any length more than a meter or a few feet.
It seems to be rigid, but its not. If you shake a length of PVC like that it will seem like a wet noodle, so avoid using PVC for structural use either, except when recommended in build plans.From experience I'm clarifying that ABS should never be used as a pole or mast, and it should be carefully considered if you're thinking of using it as a horizontal boom of any length more than a meter or a few feet.
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Yeah, I used the cheapest flat 96 cent indoor/outdoor spray I could find on my first GH build that used white pvc (that was before I discovered the grey stuff, heh). After 3 years, its held up very well outdoors. I only used 1 thin coat, just enough to cover. Using many or thick coats it will peal, whereas 1 thin coat will just slowly fade. Ive also done the same on outdoor white pvc trellises and sump pump drains for over a decade, and theyre still in great shape. Kelly green blends in nicely with leaves and grass.
Zinsser 1-2-3 latex primer is good stuff and I use it on wood. But for pvc its probably overkill.
Plumbers Goop works fine with PEX, at least for antenna usage. Maybe not for water pressure though. Im not really a big fan of using PEX for water usage either. The connections just seem weak and flimsy.
I picked up some of these usb devices cheap today:
http://siouxchief.com/Resource_/ProductMedia/63/522 Spec Sheet 10-08.pdf
Heh, usb stands for universal slider bracket.
These would be great for clamping on a CM4221 type mesh reflector onto a round pipe from 1/4" to 1 1/8" OD. Not good for a GH mesh model because of the need for a split screen.
Another thing, the clamps on it are UV resistant plastic. They clamp down on both sides just like electrical wire ties do.
http://siouxchief.com/Resource_/ProductMedia/63/522 Spec Sheet 10-08.pdf
Heh, usb stands for universal slider bracket.
These would be great for clamping on a CM4221 type mesh reflector onto a round pipe from 1/4" to 1 1/8" OD. Not good for a GH mesh model because of the need for a split screen.
Another thing, the clamps on it are UV resistant plastic. They clamp down on both sides just like electrical wire ties do.
Polyurethane glues like Elmers Glue All Max or Gorilla Glue work great for joining styrofoam and metal. I had been wanting to test this out and just recently did. It holds the piece of coat hanger to the styrofoam panel extremely securely and most importantly, it does not eat its way into the styrofoam.
So if building a GH for attic use on a styrofoam panel, all you would need to do is apply a small drop of the polyurethane glue every six inches or so. The polyurethane glues expand to about 3 - 4 times the size of the original drop as it dries. A slightly damp, but not wet, surface also helps.
I had been wanting to test this out and just recently did. It holds the piece of coat hanger to the styrofoam panel extremely securely and most importantly, it does not eat its way into the styrofoam. So if building a GH for attic use on a styrofoam panel, all you would need to do is apply a small drop of the polyurethane glue every six inches or so. The polyurethane glues expand to about 3 - 4 times the size of the original drop as it dries. A slightly damp, but not wet, surface also helps.
Its also great for joining or repairing Styrofoam end to end.
I just repaired a custom cut piece I had that the wind broke. If it breaks again, it wont be at the original break point, the joint is that strong.Update on black "UV resistant" Walmart nylon wire ties
The black "UV resistant" Walmart nylon wire ties aren't as UV resistant as I had hoped they would be. After 4 years outdoors, they are starting to fall off and are getting brittle on my DBGH gen1 mesh reflector antenna. Of course, that's still 4 times as long lasting as the white nylon wire ties outdoors in my area.
Ill probably use aluminum wire to secure the mesh to the pvc pipe instead of nylon wire ties.
All the 1/2" pvc pipe pieces and even the cheap 96 cent flat black spray paint (thin coat) I used on them and the mesh reflector are in fine condition after 4 years. Just starting to get that right touch of dark greyness in them.
Edit:
Darn it, I just remembered I used black nylon wire ties to secure the fiberglass reinforcing rods on the CM1221. Ill have to redo them too, crap.
The black "UV resistant" Walmart nylon wire ties aren't as UV resistant as I had hoped they would be. After 4 years outdoors, they are starting to fall off and are getting brittle on my DBGH gen1 mesh reflector antenna. Of course, that's still 4 times as long lasting as the white nylon wire ties outdoors in my area.
Ill probably use aluminum wire to secure the mesh to the pvc pipe instead of nylon wire ties.
All the 1/2" pvc pipe pieces and even the cheap 96 cent flat black spray paint (thin coat) I used on them and the mesh reflector are in fine condition after 4 years. Just starting to get that right touch of dark greyness in them.
Edit:
Darn it, I just remembered I used black nylon wire ties to secure the fiberglass reinforcing rods on the CM1221. Ill have to redo them too, crap.
I always glue in an old broomstick in the center of the 1 inch pvc mast to add rigidity.
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