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Author Topic: Through roof push up antenna.  (Read 814 times)

KD0HBJ

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Re: Through roof push up antenna.
« Reply #15 on: June 04, 2020, 07:11:53 AM »

"First test I would do is what pattern and gain will get me from here to there with an antenna on the house, and work the problem from that direction,"

That makes sense to me.  I was probably avoiding it due to my fear of heights.  How would I go about doing that?  Should I get a nanoVNA?  Then what. 
I don't want to buy a series of more powerful and expensive antennas till I find one that works, when the same result might be obtained by a cheap longer pole.

There seems to be consensus that getting the antenna out of the attic and on a short pole on the roof will make the difference.  That did not make sense to me because that is still below the top of the trees.  I am not resisting that, I'm just trying to understand why it would make such a difference.  So if someone could please explain the factors, that would help.

I once thought the asphalt shingles or roofing nails might be the problem, that was one of the reasons for the temporary 20ft pole test outside which failed.  That told me the roof in the way was not a significant factor, height above the leaves is.  If I misinterpreted that, please give your interpretation.

I didn't see my initial proposal as requiring much effort, but apparently y'all did.  Y'all seem to think putting antennae in trees is easy.  I don't have experience with that exactly, but putting a tire swing on a 23' branch seemed like a Herculean effort that had my back out for a week after.  I'm willing to come around, I just need to be shown the error of my ways, rather than have a person on the internet I don't know say just trust me.

The way I saw it, my plan was just 1 roof penetration at the ridge vent where it is already open versus a tripod with 3 new roof penetration sites.  That seemed like an advantage. 

Since I already have the tripod, can anyone think of a way to place it, an antenna and feedline on the roof peak(without bolts) for a test without me actually climbing the roof?  I guess that answers my previous question about what to do next.  Its weird how fear of something can block a person from seeing solutions that involve that something.
Even if the answer is as simple as just asking someone to do it for you.  I got so used to doing everything myself.
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KD0HBJ

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Re: Through roof push up antenna.
« Reply #16 on: June 04, 2020, 07:27:30 AM »

"This Yagi. How is it " polarized"? Horizontal or Verticular?"

VHF section has horizontal elements, UHF section has vertical elements.  It is a reconfigured old analog TV antenna.
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K0UA

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Re: Through roof push up antenna.
« Reply #17 on: June 04, 2020, 08:38:22 AM »

"This Yagi. How is it " polarized"? Horizontal or Verticular?"

VHF section has horizontal elements, UHF section has vertical elements.  It is a reconfigured old analog TV antenna.

Well, there is your problem right there.  get yourself a nice 4 element VERTICAL 2 meter antanna and put it back in the attic and point it in the general direction of the two meter repeaters.  OR get the cushcraft 2 meter/440 vertical yagi. OR it is possible an 2m/440 vertical omnidirectional antenna would work in your attic.  Throw your present antenna out for the trashman.  OR build yourself some VERTICAL antennas.  You are losing at least 20 dB of signal by having the wrong polarity of antenna. The fact you can hit some of the repeaters at some times with an antenna that is 20 dB down at least from the correct polarization tells me that almost ANYTHING with the correct polarization  in your attic would work.   
« Last Edit: June 04, 2020, 08:43:42 AM by K0UA »
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73  James K0UA

KD0HBJ

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Re: Through roof push up antenna.
« Reply #18 on: June 04, 2020, 11:32:02 AM »

I'd really like to believe that just buying that antenna would work year round.  The problem is it sounds just like every other sales pitch and I have no reason to believe your pitch over others.  I do know the existing antenna in winter is hitting my preferred 146MHz repeater 20 miles away.  It hits it mounted vertical or horizontal.  In summer, the same rig does not hit the repeater in either orientation.
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NN4RH

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Re: Through roof push up antenna.
« Reply #19 on: June 05, 2020, 04:43:46 PM »


If the problem is tree leaves in the way, and you think raising the antenna a couple of feet will help; then why can't you lower the trees instead? Hire someone to prune or top, or even cut down, the tree or trees that in the direction you need to clear?

Quote
I have 2 roof tripod mounts but haven't used them because its a new roof I didn't want to damage and frankly,

I'm missing something. You're talking about drilling holes all the way through your roof, which seems to me to be asking for a lot more problems than using an already-existing roof tripod.
Quote
I'm scared of the height as I've fallen from 20+ft before.
Can't hire someone to do it?
« Last Edit: June 05, 2020, 04:49:35 PM by NN4RH »
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W9IQ

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Re: Through roof push up antenna.
« Reply #20 on: June 06, 2020, 04:52:00 AM »

Dustin,

You stated that when the trees leaf out that it is 'game over'. Can you still hear the repeaters? How many different UHF and VHF repeaters are involved?

- Glenn W9IQ
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- Glenn W9IQ

God runs electromagnetics on Monday, Wednesday and Friday by the wave theory and the devil runs it on Tuesday, Thursday and Saturday by the Quantum theory.

KD0HBJ

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Re: Through roof push up antenna.
« Reply #21 on: June 18, 2020, 11:57:44 AM »

We had some trees pruned when we moved in.  It was horribly expensive and it killed the trees within 2 years.  The trees in the way are over 100ft, beautiful, shade our yard just right, have a seasonal creek running through them, and are very close to the property line.  Frankly I care more about the trees than the radio.

The tripods I have came with me when I moved.  They are used on the ground for field day and are currently in the garage, not on the roof.  But they were originally designed for roof installation so they are available.  Sorry that wasn't clear.

I guess I could hire someone to put them up.  I do not think "a couple of feet will help".  I think 20 or 25 feet will help, but I don't know.  I cannot leave 20-25 feet up all the time.  I will get complaints.  I figured a 6 foot mast that I can raise on demand to 25 will get less complaints.  More importantly, if they come to measure I quickly lower it to legal height.

@W9IQ, The main System Fusion repeater I want to hit disappears (nearly)entirely.  I've heard it briefly with lots of static in early evening on FM while the leaves are on, but never breaks squelch in DN mode.  I can hear it in DN mode from the car at a ridge about 3 miles up the road.  Tx into it about 8 miles up the road.  Between 3 and 8 miles the road dips and is tree covered. 

There is a closer FM only VHF repeater which I can hear most of the time, but only transmit to while in the car when leaves are on.  There is a UHF FM repeater in a different direction that I can hit all the time if I rotate the antenna toward it, but it has very little traffic. 
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W9IQ

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Re: Through roof push up antenna.
« Reply #22 on: June 18, 2020, 01:35:56 PM »

Before you go to the expense and effort of raising your antennas and not being sure if it will change your situation, you may wish to try an experiment of raising a small transmitter or vertical antenna with a drone, a balloon, or a telescoping mast to find the height at which you can hit the repeater(s).

If you do it with a vertical antenna and a balloon, you will need to include the weight of the coax and the antenna in the lift calculation. The balloon could be a helium or hot air version but either would require a still day so that it rises nearly vertically. Ideally, you would like to be able to vary the transmitter power so that you can determine how much input power is required at a given height to hit the repeater (generally you will hear it before you can hit it). Then you can then deduct the coax loss to determine the input power to the antenna that is required at that height.

As a ballpark number, it would take a balloon of about 5 feet in diameter filled with helium to lift 3 pounds, including the weight of the balloon. 50 feet of RG-8X cable would weigh about 1.9 pounds. Add to that the antenna and balloon weight and you are about there.

If you use a lighter coax or just use a transmitter, a DJI Inspire 2 drone can lift ~ 1.8 pounds. Or SOTA and MFJ make telescoping masts in the 30-35 foot range.

- Glenn W9IQ

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- Glenn W9IQ

God runs electromagnetics on Monday, Wednesday and Friday by the wave theory and the devil runs it on Tuesday, Thursday and Saturday by the Quantum theory.

KG5AHC

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Re: Through roof push up antenna.
« Reply #23 on: June 18, 2020, 02:58:38 PM »

"This Yagi. How is it " polarized"? Horizontal or Verticular?"

VHF section has horizontal elements, UHF section has vertical elements.  It is a reconfigured old analog TV antenna.

When you say reconfigured... is it resonant in the amateur VHF and UHF allocations? If not, you are loosing receive and transmit efficiency. As others have mentioned, it is critical to use vertical polarization for FM repeaters.

As far as attaching winch line to bottom of a rotatable pole, you would need a thrust-bearing for the pole to sit on, with the bearing mounted on a platform that the winch raises and lowers (in some kind of guide rail I suppose).

And as always with roof mounted antennas... LIGHTNING PROTECTION routed OUTSIDE of house structure to ground.

Regards, Jeff KG5AHC

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W9IQ

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Re: Through roof push up antenna.
« Reply #24 on: June 18, 2020, 06:07:26 PM »

When you say reconfigured... is it resonant in the amateur VHF and UHF allocations? If not, you are loosing receive and transmit efficiency.

My usual reminder that resonance and efficiency are not directly related.

- Glenn W9IQ
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- Glenn W9IQ

God runs electromagnetics on Monday, Wednesday and Friday by the wave theory and the devil runs it on Tuesday, Thursday and Saturday by the Quantum theory.

KG5AHC

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Re: Through roof push up antenna.
« Reply #25 on: June 18, 2020, 06:38:38 PM »

When you say reconfigured... is it resonant in the amateur VHF and UHF allocations? If not, you are loosing receive and transmit efficiency.

My usual reminder that resonance and efficiency are not directly related.

- Glenn W9IQ

Very true. I should have described my point differently.
Cheers.
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W8BO

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Re: Through roof push up antenna.
« Reply #26 on: July 01, 2020, 05:05:59 AM »

"You can get some ideas watching Hogan's Hero's on FETV...
They had one built into the Nazi flag pole on top of the roof."

Dude..you stole my thunder!

My brother had success with one of these Ventenna's, if Omni will suit you:

https://www.ventenna.com/
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AC2RY

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Re: Through roof push up antenna.
« Reply #27 on: July 03, 2020, 12:52:54 PM »

Cutting through the roof will be much more expensive comparing to installing all new antenna. If you reception is poor - use antenna with higher gain. Something at least 6dB better than you have now. That will likely solve your problem.

Also having mast at the middle of the roof will increase chances of lightning damage. It is always the best to have antenna as far away from structure as possible and have it properly grounded.

Keep in mind that repeaters are designed to provide mobile service, not to serve a base station. If you cannot get to repeated from handheld radio from your back yard, you better think about other ways of communication - like getting General license and operate on HF bands.

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WA9AFM

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Re: Through roof push up antenna.
« Reply #28 on: July 05, 2020, 05:18:05 PM »

Hi Dustin!
Just build yourself one of these!
https://www.youtube.com/watch?v=qsh9HWm95_o

Let us know how it works!

Kidding aside, I agree with Mark.  Unless you want to spend the bucks, you'll likely encounter more headaches and irritating challenges than desired results.

Good luck,
73 Pete

Former Titan II crew member. Our HF discone antenna got blown away in a standard issue Kansas thunderstorm.  We were on the 'hard HF' antenna for a couple of months awaiting a replacement discone.  That vertical works like gangbusters.
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K4PIH

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Re: Through roof push up antenna.
« Reply #29 on: July 15, 2020, 05:06:08 AM »

I think I can sum it up. Move if possible.
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