teds12
03-20-2005, 06:54 AM
I'm at a loss as to where to put my new CM3021 4 bay UHF antenna. I don't want to lose 1/2 of the signal strength via my attic and I have an FM antenna on my chimney location. I was going to mount the CM3021 above the FM antenna using a "mast insertion" but the entire rig is 15 years old and rusted/frozen in place. I could hack saw off the works and start over with all new hardware including the FM antenna, or I could use a vent pipe (the roof is very high off the ground and I'm not good on ladders for a shingle/side of house at the roofline effort).
There is this metal vent pipe about 18" long in the right spot, a radio shack vent pipe mounting kit, a 2.5 foot Home Depot mast, and it looks easy enough...
Does anyone have a reason why this would be a bad move? My logic is that the wind resistance of the CM3021 looks negligible and the antenna and mast only weigh about 4 pounds. (I would try hard not to damage the pipe when I do the job.)
amf1932
03-20-2005, 03:15 PM
In the past I've used the vent pipes to mount antennas(big yagi arrays) and also rotator assemblies with absolutely no problems. ;)
Alan
rbinck
03-20-2005, 06:09 PM
As long as the plumber secured the vent pipe securly in the attic, there will not be a problem. It is a good idea to run a grounding jumper to a cold water pipe and use a grounding block on your RG6.
amf1932
03-20-2005, 07:40 PM
Generally, metal vent pipes are grounded.....from my understanding, after talking to plumbing companies that work on newly constructed buildings.
Alan
rbinck
03-20-2005, 08:41 PM
Most vent pipes are connected into the sewer part of the plumbing system, assuming we are talking about a lavatory or sink trap vent pipe. Many installations use plastic piping for the sewer except for the vent where it transitions to metal. In any case sewer piping is not considered grounded. In fact CEDIA recommends using a ground rod and not to trust cold water piping because of all of the plastic in use these days. Now if you want to trust a plumber for electrical advise, go ahead, I guess, but I still recommend grounding the antenna and grounding block. For sure I would not assume the pipe is grounded.
teds12
03-20-2005, 09:09 PM
rbinck,
Thanks for the perceptive input!
I had run heavy gauge aluminum grounding wire to my basement water piping for the FM antenna on the chimney. Do you recommend the same approach for the CM3021 on the vent or is simply running the RG6 into and then out of my Belkin stereo/tv surge protection system ahead of my HDTV sufficient to fulfill the grounding suggestions I received here?
RSawdey
03-21-2005, 01:07 PM
I had run heavy gauge aluminum grounding wire to my basement water piping for the FM antenna on the chimney.
Make sure you are connected to the COLD water line... connecting to the hot pipes will eat the sacrificial anode in your hot water heater & can also eat your pipes with galvanic action.
rbinck
03-21-2005, 06:20 PM
Assuming the ground wire is connected to a cold water pipe, you can jumper from the FM antenna ground wire to the new antenna. Be sure to use a grounding block http://www.radioshack.com/images/ProductCatalog/ProductImage/15/t15-920.jpg (http://www.radioshack.com/product.asp?catalog%5Fname=CTLG&product%5Fid=15-920) to drain static from your RG6 as well.
Dual Grounding Block (http://www.radioshack.com/product.asp?catalog%5Fname=CTLG&product%5Fid=15-920)
