Earwave
Member
Its a vent pipe for the bathroom plumbing,located near the peak of roof.I think its 1 1/4 pvc.feels sturdy enough.Has anybody done this?Is this a bad idea?
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install D-130J on rooftop pvc vent pipe?
- Thread starter Earwave
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RadioDaze
Member
How windy does it get there?
Earwave
Member
Usually under 10mph here.The discone design seems to be bottom heavy rather than top heavy,which would be a plus.
RadioDaze
Member
Inspect the pipe periodically at the flashing to make sure the waterproofing isn't starting to show a gap from repeated movement due to wind. (Or whatever applies depending on the construction.)
Sorry to be a killjoy or something, but I feel I have to pass on the same advice I was given when I asked a similar question a few years back..and it paid off in my mind, 3 + hurricanes later 
Your idea could work, I have done something similar, for a temporary setup...If your only going to mount 1 small discone, you would likely be ok, I would try to keep it as close to the rooftop as possible so it doesnt catch so much wind, and I would steer away from adding more PVC or metal pipe to add height, as it could cause problems(sway, cracking of original pipe) And of course, as Gewecke said, make sure you ground it properly..
Now for the killjoy part You really need to consider what its going to cost you to fix your roof, bathroom plumbing, attic insulation, ceilings, and maybe more if you snap that pipe, or tear part of your roof off, or who knows what else..you would be better off to think of a more perminant solution, at least something attached to a less vital area of your home(chimney, deck, braces attached to side of house), or not attached at all. It may cost you some cash now, but better to pay a little now, than pay a whole bunch more, later..on something you could have avoided all together.
Your idea could work, I have done something similar, for a temporary setup...If your only going to mount 1 small discone, you would likely be ok, I would try to keep it as close to the rooftop as possible so it doesnt catch so much wind, and I would steer away from adding more PVC or metal pipe to add height, as it could cause problems(sway, cracking of original pipe) And of course, as Gewecke said, make sure you ground it properly..
Now for the killjoy part
You really need to consider what its going to cost you to fix your roof, bathroom plumbing, attic insulation, ceilings, and maybe more if you snap that pipe, or tear part of your roof off, or who knows what else..you would be better off to think of a more perminant solution, at least something attached to a less vital area of your home(chimney, deck, braces attached to side of house), or not attached at all. It may cost you some cash now, but better to pay a little now, than pay a whole bunch more, later..on something you could have avoided all together.
Earwave
Member
Roger that! I think I'm gonna go for it.Was hoping to hear from somebody that has actually tried it.Never thought about a chimney mount,that would be another way to go.
Ok,my turn to be the killjoy,lol! Chimney mount kits work great but be sure your chimney is stable,obviously and space the straps as far apart as possible to equalize the wind load.
With only a D130J you shouldn't have much to speak of,so be careful and enjoy!
73's and happy 4th of july!
n9zas
With only a D130J you shouldn't have much to speak of,so be careful and enjoy!
73's and happy 4th of july!
n9zas
W2NJS
Member
I've had two roof antennas up for more than seven years, mounted on METAL vent pipes. The mounts are directly on the pipes with no mast extensions. Both antennas are fiberglass, one being about six feet and the other about nine feet tall. I've had them checked for wear, cracking, looseness, etc. and so far no problems at all but, again, these are metal vent pipes. Also, FWIW, feedlines are RG8U on one and 9913 on the other.
killmoles
Member
I've had the Radio Shack discone mounted on my vent stack since approx 2002 with the cheap Radio Shack vent mount that you can still find online at other places. It was on 7' of 1.25" EMT until 2005 and never had an issue, even through several storms of 70+ MPH winds. In 2005 I changed the mast to a full 10' section and also attached 80/40 Meter dipole type antennas. The past couple years I've noticed the dipole pulling the mast away from the house and to the left slightly, but I'm sure it would still be vertical if the discone was the only thing attached or if I had a better attachment to the vent. We've also has several ice storms which might have something to do with it. My vent is galvanized steel from the 1950's, not PVC. I also have #6 copper wire grounding the mast to an 8' ground rod and don't take a shower when there is lightning! I'm in the process of planning a tower and this will all be coming down soon, but it's served me well with practically no maintenance.
All that said, I wouldn't hesitate to mount a discone on a solid vent pipe, or even PVC in a low wind area, which I'm not in.
All that said, I wouldn't hesitate to mount a discone on a solid vent pipe, or even PVC in a low wind area, which I'm not in.
Nice pic killmoles, gotta love that old construction, metal is great
Earwave
Member
Thats exactly what I was hoping to hear,and the pic is frosting on the cake.
I knew there had to be at least a couple of people that have tried this.
I dont think I'd get away with using a 10' mast on this pvc pipe.It comes through the roof about a foot from the peak,so I'm planning on attaching
directly to the pvc,with no additional mast,if the lower element rods will allow it.
thanks for the input all.
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