If you've ever tried to get a "vent mount" really tight on a 2" vent stack, you soon realize that the clamp closes and "bottoms out" before the clamp gets a serious bite on the pipe.
My VHF/UHF antenna mounted on a vent had done "okay" on such a vent mount, but was a couple of degrees off plumb after the first Santa Ana wind hit it. I figured I'd just find a heavier model and replace it. I hadn't found one (no longer stocked at my local radio shack. Nice cell phone selection tho...) to replace it with when So. Cal got it's big "wind event" a few weeks ago. After some 80MPH gusts the first night of the "event', I kept checking my antenna's with a flashlight to make sure they were still on the roof. The next morning my vent mounted antenna was at about 30 degrees.
Glad it was in the air at all really, because it outlived this entire line of power poles right behind my house.
With two more days of wind expected, I got up on the roof and pulled both antennas rather than collect them from the neighbor's windshield later. lol When I got on the roof, it was obvious to see that the mount had simply twisted on the vent stack, causing the mast to lean.
After getting it down and coming up empty on a search for a replacement locally, I decided to modify this one to take up some of the I.D. of the vent clamp. I bought a 1/8" X 1" X 3' piece of steel flat stock for about $6 and cut it in to four pieces. I was just going to slip these inside the clamp and tighten it down, but decided I'd tack it to the clamp since I had a wire welder sitting here collecting dust.
Ugly welds, but very effective. Not only did the flat stock reduce the clamp's I.D., but it also tied the top and bottom clamp together, eliminating the twisting issue (even if one or the other DID manage to slip on the vent).
We've had Santa Ana winds with 60+MPH gusts since I re-mounted the antenna and it didn't budge. Easy fix if your vent mount doesn't get as tight as it should. Even without the welding, just adding the extra steel inside of the clamp would be a huge improvement on a 2" vent installation over the 'stock' mount.
My VHF/UHF antenna mounted on a vent had done "okay" on such a vent mount, but was a couple of degrees off plumb after the first Santa Ana wind hit it. I figured I'd just find a heavier model and replace it. I hadn't found one (no longer stocked at my local radio shack. Nice cell phone selection tho...) to replace it with when So. Cal got it's big "wind event" a few weeks ago. After some 80MPH gusts the first night of the "event', I kept checking my antenna's with a flashlight to make sure they were still on the roof. The next morning my vent mounted antenna was at about 30 degrees.
Glad it was in the air at all really, because it outlived this entire line of power poles right behind my house.
With two more days of wind expected, I got up on the roof and pulled both antennas rather than collect them from the neighbor's windshield later. lol When I got on the roof, it was obvious to see that the mount had simply twisted on the vent stack, causing the mast to lean.
After getting it down and coming up empty on a search for a replacement locally, I decided to modify this one to take up some of the I.D. of the vent clamp. I bought a 1/8" X 1" X 3' piece of steel flat stock for about $6 and cut it in to four pieces. I was just going to slip these inside the clamp and tighten it down, but decided I'd tack it to the clamp since I had a wire welder sitting here collecting dust.
Ugly welds, but very effective. Not only did the flat stock reduce the clamp's I.D., but it also tied the top and bottom clamp together, eliminating the twisting issue (even if one or the other DID manage to slip on the vent).
We've had Santa Ana winds with 60+MPH gusts since I re-mounted the antenna and it didn't budge. Easy fix if your vent mount doesn't get as tight as it should. Even without the welding, just adding the extra steel inside of the clamp would be a huge improvement on a 2" vent installation over the 'stock' mount.
