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Maco v quad installation help

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  #9  
Old 02-29-2012, 01:00 AM
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I really have no other option.The v quad is 7 or 8 lbs the rotor another 4 lbs.A 4' mast 2 hold the rotor and a 1' mast between rotor an v quad.Thats about 12 or 13 lbs.That would bring down the chimmeny.I figure if i keep the mast short it would'nt move a lot.short an stout.Less vibration...How do i ground my station an antenna...Please help an thanks 4 the get back.

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Old 02-29-2012, 06:37 AM
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roof antenna mount tripod - Google Search

You could look at something like this mount if you do not want to use the chimney.

Last edited by wavrider; 02-29-2012 at 06:37 AM. Reason: spelling

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Old 02-29-2012, 07:01 AM
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greetings;

i would not be drilling any holes into the chimney, if i'm seeing it right this sounds to be a small chimney to vent gases maybe from a gas furnace or other gas appliance but let us know if it is other wise.

i would check the integrity of the mortar and bricks well. I lived in an older house built in the 40's at one time and the mortar was falling apart after 45 odd years just from the elements alone.

My preference(if the integrity of the chimney is good) would be to use mounting hardware with stainless steel straps that wrap around the entire chimney.

Some folks say that standard antenna mounts are ok, but i like to be sure because there are considerable wind forces on the mast and antenna.

What would be worst case scenario, the chimney crumbles you may or may not be able to use said appliance, you hire a mason to rebuild you a chimney, then you buy a separate mast or tower. Just thinking outloud here, i like to think things through.

Hope this helps out and not hinders any. Best of luck

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Old 02-29-2012, 11:29 AM
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I use a Mosley TA33JR mounted on my garage. I used a 3' tripod from Radio Shack. 5' mast to the rotor, then another 5' to the beam. I also guyed the bottom of the rotor to the roof to cut down twisting and spread out the wind load. Braced in the rafters, used stainless bolts and lots of silicon to seal. Been up for about 10 years and still running strong. No leaks in to roof either.
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Old 02-29-2012, 11:34 AM
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Quote:
Originally Posted by wavrider View Post
The V quad if I am not mistaken uses a gamma match to adjust the impedance.

An RF choke is not needed to prevent CMC, but as ROBB said it sure would not hurt anything.
A gamma fed antenna won't create CMC?


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Old 02-29-2012, 12:16 PM
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Quote:
Originally Posted by 359 View Post
A gamma fed antenna won't create CMC?


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The transmission line (coax) shield is not part of the antenna or counter poise per say.

Common mode current

Some reading on CMC.

The Gamma match provides a transition from unbalanced coax to balanced antenna. Adjusting the Gamma for lowest Z or VSWR if only a VSWR meter is available will usually eliminate CMC as equal but opposite currents are flowing on the transmission line.

I have never seen a yagi excited with proper drive cause CMC, now I have seen amplifiers being over driven into saturation and beyond cause splatter but the yagi can not be blamed for the splatter, the operator sure can.

Last edited by wavrider; 02-29-2012 at 12:18 PM. Reason: the usual

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Old 02-29-2012, 12:25 PM
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I used the bottom 3 sections of a heavy-duty 5 section telescoping TV mast for my 13' long (.2 /.15) 3 element quad.
The bottom telescoping section was 10' and I had the next two extended 9' and 8' respectively, plus a 30" mast coming from the top of the HD-73 rotator. This was all on a 20' roof peak and guyed 4 directions so the boom was right at 50'.
Having no tower it was all I could do, and it lasted for over 10 years without issue before I took it down to try something different.
I didn't use a tripod at the bottom, I simply walked it up and set the bottom of the mast into the roof-mounting base (after setting the 12 well-insulated guy wires during a dry-run without an antenna on it) with the beam and rotator installed but collapsed down to about 15' total, then I leaned a ladder against the mast and pushed up the 2 top sections until the I saw the marks, then tightened the turnbuckles until taught & true.
It was a little hair-raising but it only took an hour or so afterword for my nuts to drop back down.

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Old 02-29-2012, 12:40 PM
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This V-quad antenna @ 13 lbs is fairly light weight. However, if you live in a part of this country visited regularly by high winds, it may not be advisable to use the chimney as a mount. Although this beam might be light, its surface area (believe it or not) does provide wind load. The greater the wind; the higher this load will be.

This wind load can also put a great deal of unwanted stress on a rotor too. This side load force can break or shear the rotor housing. The remedy for this is to use a support bearing; and this will handle massive side load forces. i don't use one, as the rotor I am using has quite a bit of overkill for the beam size I am using. But for lesser rotors, $30 for a support bearing is money well spent. Or, you could make one. It doesn't need to have a bearing per se, even a small section of steel tube can be used as an 'axle housing' if you know to use tools and simple hardware.


Source:
http://www.starkelectronic.com/cmmatv.htm#rotor

I use a 35 ft push-up pole attached at the base to the side of my building at two points. Then, guyed at the rotor to four points below with dacron rope. We had some stiff winds here last night here in CA, and the beam did very well. At one time I did consider using the chimney, but felt I just didn't want to risk it.


Source:
Sirio SY27-4 Beam Install

A push-up pole can be fairly expensive if bought new; the shipping cost can be outrageous. But you can use 36 ft of 1 1/2 in galvanized water pipe; just support it along its length using the building as a support. I cannot foresee a problem with that. Probably 1/3 of the cost of a push-up pole and easier to acquire.

Just some thoughts . . .

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Last edited by Robb; 02-29-2012 at 01:46 PM.

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