James,
My counterpoises droop more than the 1-2 feet mentioned, perhaps due to
repeated icing.
However, the slope of the counterpoises impacts the impedance of the
antenna. From what I recall, the impedance rises as the counterpoises slope
downward, up to a point. So I would advise against lifting them in any way.
This antenna is a 3/8 wave radiator with a nominal feedpoint impedance of
about 200 ohms. In this regard it is SOMEHWHAT similar to an OCF dipole, in
a sense "similar" to a 1/4 wave vertical acting similar to a dipole with
half of it buried in the ground. My main point here is that I believe
letting the counterpoises slope naturally is an important element in this.
As for mounting, I had one on a 1.75" pipe, about 8' long, and during the
big Ozarks ice storm two years ago it came down: the pipe folded over; the
AV640 was largely intact. So be careful about what you put it on.
For mine, I have about 11' of 4" pipe with a hinge on it, buried in
concrete. Dummy me...I over-engineered and could have it up higher...but
never mind. Then there is the hinge and another 8' or so of 3" or 2.5" OD
heavy wall pipe. I could likely mount a small yagi on it, but at least I'm
not worried about the mount falling apart.
Write off the list if you want pics or anything.
73,
Art
----- Original Message -----
From: "Richards" <jruing@ameritech.net>
To: "Roger (K8RI)" <K8RI-on-TowerTalk@tm.net>
Cc: <towertalk@contesting.com>
Sent: Sunday, December 28, 2008 5:23 PM
Subject: Re: [TowerTalk] Hy-Gain AV-640
>I have yet to install my AV-640 which remains in the box -- I am
> STILL all unsure, worried, and obsessing over how I can install
> it over the front corner of my attached garage or other location
> in the yard. (I have a big 43 foot monopole vertical in the middle
> of the back yard...) and have been considering:
>
> 1) 20 feet of RG type lightweight tower (e.g. two sections)
> braced against the house/rafters/eaves
>
> 2) A twenty foot 1.75 inch heavy galvanized iron water pipe,
> set in a couple feet of concrete at the base, and braced
> against the house/rafters/eaves
>
> 3) a 3-5 foot roof tower and 5-foot mast set in the middle of
> the garage roof. (Wife does not favor holes in the roof...
> but is OK with options 1 and 2 - but will not cry about this
> option if it is best and can be done safely and securely -
> and I share these concerns... especially after the 50 mph
> wind storm last night that shook the house all night....)
>
> 4) A ten to 15 foot 2-inch galvanized water pipe set somewhere
> in the yard far enough away from the house and the big
> vertical in the back yard... I can put it AT MOST about 50
> feet from the big vertical if I put it in a corner of the back
> yard, but I have rather narrow side yards (avg sized
> suburban lot)
>
> 5) ???? (Any other options I should consider...)
>
> ISSUE = How to mount it so it can tip down and I can access
> it for tuning? Can I stand on the roof to tune it if it can be
> tipped over on the mast or tower section?
>
> ISSUE = How high must it be over the roof (and gutters) if I
> brace it against the side of the garage? How much do the
> counterpoise radials droop (and can I suspend them
> with light rope to keep them from drooping without causing
> a wind loading or other problem?
>
> ISSUE = How should I guy it if I mount it over the roof
> (and gutters) if I brace it against the side of the garage?
> I can tie off to the garage sides and roof on three sides
> of it, but then the side away from the house/garage needs
> something... or does it? Are three quarters sufficient?
> Does not seem balanced that way. Again, I have a narrow
> side yard and do not want a problem with the neighbor kids
> or lawn mower service... I do not have quite the space Roger
> has for guys... DO I NEED TO GUY IT... really? (Yeah... I know
> an ounce of prevention...)
>
> ANY IDEAS GREATLY APPRECIATED. I WOULD LIKE TO GET
> THIS UP SOON...
>
> I admit to obsessing, but my big vertical sustained 60 mph winds
> last night with no problems, so I am 1) able to finish the project
> if assured by good plans, and 2) get good results by good
> planning.
>
> ============= James // K8JHR ================
>
> Roger (K8RI) wrote:
>
>> I've used an AV640 for a couple of years now
>>
>> As for guying I'll just include the link:
>
> =============================================
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>
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