Ways to attic mount a discone

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KI5IRE

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Just bought a discone antenna for my attic (I l live in an HOA neighborhood so roof mounting is not an option) and am looking for ways to mount my antenna without having to leave off any spokes due to studs etc.


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mmckenna

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Not a discone, but I have a TV antenna mounted in my attic. I just used a length of 1" PVC pipe screwed to the rafters.
 

AlphaFive

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Discone

Also use the peak beam. I have four discones hanging averaging 7 feet or so apart, more or less. I take a small eye bolt, screw it into the peak beam. Then use heavy twine cord and hang the top/800 MHz portion of the antenna with the cord. They about 6 inches above the insulation layer. No problems at all. I am fortunate that I have no furnace or A/C units in my attic, it's clear of interference, which would be a concern.
 

chief21

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Mounting options can depend on how open your attic space is. If you have any vertical studs or truss elements, you could just install a horizontal 1x4 or 2x4 several feet above the attic floor between two existing vertical studs and use the horizontal piece to support a vertical mast - either TV mast or PVC. Mount the mast to the horizontal piece with a conduit clamp of the proper size or similar. The bottom of the mast would rest on the attic floor. Simple.
 

KI5IRE

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Got the antenna up in the attic. Found a piece of 2 x 4 in the garage and put for nails into an attic stud and connected my mounting bracket to the 2 x 4 and got it hanging in the attic. Hearing pretty good on frequencies close by and some pretty far analog and one full digital P25 system that's also pretty far out. There's a few cities I'm really surprised I am not getting with the antenna, could it maybe because I haven't removed the little rubber caps that came on the end of my spokes? Wasn't sure if they are supposed to stay or not.




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jonwienke

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could it maybe because I haven't remove the little rubber caps that came on the end of my spokes?
No. Their presence or absence will not have any significant effect on RF performance.
 

KI5IRE

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Rubber caps are just there so you don't poke your eyes out :)
Yeah, I kinda figured, and thought they may have also been to keep ends from being damaged during installation or something. Thought I'd try it with the caps so they don't get lost if I needed them. :)

No. Their presence or absence will not have any significant effect on RF performance.
Darn, any clue if there's anything to tune on a discone or any tricks to possibly increase the range? I am up as far as I can go in my attic.
 

jonwienke

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Darn, any clue if there's anything to tune on a discone or any tricks to possibly increase the range? I am up as far as I can go in my attic.
There's nothing to tune. The only way to improve performance is to get it outside and up higher.
 

Ryangn

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Darn, any clue if there's anything to tune on a discone or any tricks to possibly increase the range? I am up as far as I can go in my attic.
You could try a preamp. One may or may not work for you so it's up to you if you want to try it or not. Some people are absolutely against them and some swear by them. Other than that outside and higher is it.
 

mmckenna

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Darn, any clue if there's anything to tune on a discone or any tricks to possibly increase the range? I am up as far as I can go in my attic.
As Jon said, getting it outside and up higher is important.

Most of the frequencies you will listen to travel line of sight. If your antenna can "see" the transmitter, you'll likely be able to hear them. If there is mountains, hills, large buildings, etc. in the way, you'll have issues.

Since discones are low gain antennas, they really don't do anything more than pick up what's there and pass it down the coaxial cable. They don't provide any gain, directionality, etc. The only real benefit to a discone is that they are extremely broad banded.

By getting your antenna up higher, the radio horizon will be farther off. Also, almost all building materials have some RF attenuation characteristics, so you are losing a tiny bit of signal due to the plywood and roofing materials (you don't have a metal roof, do you?).

One other thing you can do is to use lower loss coaxial cable. Since all coaxial cable has some loss inherent to them, and that loss is multiplied by the cable length. To overcome that, you either need to shorten your coaxial cable run or use higher grade cable.

Other option is to use a pre-amplifier mounted at the base of the antenna. These boost the received signal at the antenna and increase what's sent down the cable. It's not a "free" solution, though. Amplifiers can increase nearby signals so much they'll overpower the receiver. Think being at a loud party and trying to listen to someone across the room whispering. Amplifiers also increase unwanted noises.

Sounds like it's actually working pretty well given what you've got. Just be careful, chasing those far off signals can get expensive, time consuming and dangerous.
 

Ubbe

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If you're not that concerned about having extra gain at 30-40MHz you could remove the top antenna and raise the discone as far as it goes. If you have your neigbours houses equals the height of yours, then you will gain a lot by having the antenna as high as possible.

I would recommend a low noise amplifier as your antenna is inside the house. Look in ebay for low noise amplifier and less than 1.0dB NF. Most of them use USB power and SMA connectors so you'll also need pigtails to convert from N or PL whatever your discone uses. Some amplifiers have inbuilt FM traps or you could buy them seperatly from the same place. Important are to have a variable attenuator at the scanner to adjust for optimum reception without overloading the scanner.

I suggest looking here: http://stores.ebay.com/GPIO-Labs and some pig tails:http://stores.ebay.com/customcablesgroupllc Buy something like this locally: antennas direct variable attenuator | eBay or search on ebay for the items and wait 3-4 weeks for delivery and get them 10 times cheaper from China.

/Ubbe
 
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