And make sure that the flange is being bolted into a stud and not just the sheathing. A good gust could pop it off especially if the arm is long.
Great idea though! Dave (who just got a Tbolt and waiting on an antenna) I am doing a tower for my ham radio stuff and want to put the Tbolt on the other side of the house to gain some isolation. > -----Original Message----- > From: time-nuts-boun...@febo.com > [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob Camp > Sent: Sunday, June 10, 2012 17:53 > To: Discussion of precise time and frequency measurement > Subject: Re: [time-nuts] Thunderbolt cabling questions > > Hi > > Sorry for the blank. > > The easy way to mount the antenna: > > Head over to Home Depot and get a 1" Tee, a 1" flange, a 1" > nipple, a 12" to 18" 1" pipe, and a 6" long 1" pipe. > > The antenna goes on top of the 18" pipe. That screws into the > tee. The bottom of the Tee gets the 6" pipe. Coax runs > straight through the 18" and 6" pipe. Nipple goes to the > flange and the tee. Flange mounts to the house. If you need > to get a bit further out, change out the nipple for a piece of pipe. > > Spray paint it all black ( or what ever) and move on. > > Bob > > On Jun 10, 2012, at 7:43 PM, Jim Lux wrote: > > > On 6/10/12 4:24 PM, Chris Albertson wrote: > >> On Sun, Jun 10, 2012 at 2:50 PM,<b...@lysator.liu.se> wrote: > >> > >>> ... 3m > >>> of antenna cable is no problem. Antenna position is more > important than > >>> the exact type of antenna. I'd rather have a decent > antenna at a very good > >>> site, than a very good antenna at a slightly worse antenna site > >> > >> > >> > >> 3M is trivial. 30M will work fine too. > >> > >> I agree about the location really mattering more than > anything else. What > >> I did was drill a 2" hole through the roof up from the > attic and push a 10 > >> foot gallanvised iron plumbing pipe up. > > > > you would probably want appropriate flashing around that to > prevent water (and vermin) ingress. > > > > > > The antenna sits on thop ithe > >> pipe and is higher then the roof top ridge and then the > cable go down the > >> center of the pipe. I pipe flange on top of the pipe > makes a perfect > >> mounting platform. I used a timing antenna comes inside > a white pointed > >> plastic radome. These sell for just under $30 on eBay. > Maybe it is > >> coincidence or not but the four holes pin the standard > pipe flange match up > >> with the four holes in the bottom of my antenna and there > is enough room > >> inside the hole in the center for an "N" connector. It > is worth getting > >> the antenna "done right" because it is the most important > part of the > >> entire system. Those dome type antenna are worth it. > the shape is > >> designed to shed both bird poop, and snow. Birds can be > an issue with a > >> flat top antenna, no snow here. > > > > You probably get snow every few decades (it snowed in > Malibu a couple years ago, for instance), but I wouldn't > worry about snow loads, even so. <grin> > > > > > > HOWEVER, your scheme is going to be tricky to pass muster > with the National Electrical Code. Two aspects need attention: > > You need to have a ground wire from the mast to the ground point > > and > > You need to have some form of ground of the coax shield at > the point where the coax enters the building. (a "listed > antenna discharge unit" is the usual way). > > > > > > While Southern California isn't exactly the lightning > capital of the world, we do get some. A bigger concern (and > the primary reason for the code requirement) is that above > ground power lines can come down and touch your antenna. > > > > And someone living in a more lightning prone area is going > to want to take those precautions. > > > > The installations I've seen typically use the same general > "pipe" scheme (using rigid conduit, which looks a lot like > pipe, but has a smooth inside with no burrs) to a box on the > roof, and then regular conduit running down the outside of > the building. Then at the point of entrance, the ground > bonding conductor goes from the conduit to ground, and > there's a coax grounding block in a box at the place where > the hole in the wall is. > > > > > > Granted, if lightning does hit, everything connected to the > antenna is going to fry, unless you have some sort of > reradiation scheme to provide an air gap. That's what we do > when we test GPS receivers destined for space, where you > don't want to take the risk of killing the expensive flight hardware. > > > > > > _______________________________________________ > > time-nuts mailing list -- time-nuts@febo.com > > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > and follow the instructions there. > > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.