Richards wrote:
> 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
>
Works fine
> 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
>
>
Also works fine, but is heavier than two sections of tower and not as
strong but normally less expensive. Works fine if either bracketed to
the eves, or end of roof.
> 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...
>
The only holes are the lag bolts into the rafters.
> 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....)
>
>
Only 50. Some (quite a few) of the cells going through this area were
moving at over 140 mph. very few were moving much less than 80.
surprisingly the wind at ground level was not all that bad...at least
then. When the front went through we were looking at 40 to 50 mph winds
with gusts well in excess of 60-65.
> 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)
>
>
That's pushing your luck without guys.
> 5) ???? (Any other options I should consider...)
>
> ISSUE = How to mount it so it can tip down and I can access
> it for tuning?
I set up two pipes. with one about 10' and the other about 12'. Using a
bracket I hinged the longer to the top of the shorter. I also had a
bracket at the bottom so when the mast was upright, I could pin it in
place. HOWEVER, you need to get at the stub adjustment as well as the
individual pieces of the top hats and the overall length of the antenna
(sets 40 meter resonant point). Fortunately if you follow the manual
closely it should come out just about right. Otherwise there's a lot of
adjustments. Another "fortunately" is that unlike most multiband
verticals the tuning does not interact so you can tune it one band
at-a-time without worrying about the performance of others.
I should add the AV640 is VERY sensitive to nearby antennas on any of
the bands it operates on. A 40m, half wave, center fed, sloping dipole
between 30 and 40 feet to the SW of mine changes both the resonant
frequency and minimum SWR on both 40 and 15.
> Can I stand on the roof to tune it if it can be
> tipped over on the mast or tower section?
>
>
Yes
> 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
>
The manual has a section on this, but it states, 5 ' minimum.
> counterpoise radials droop (and can I suspend them
> with light rope to keep them from drooping without causing
> a wind loading or other problem?
>
The drooping is not a 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?
The antenna is like a "wet noodle" in the wind, although it can handle
30mph without damage.
> Are three quarters sufficient?
>
three quarters? It should be guyed at *roughly* 120 increments, but you
can take a lot of license/variance in that.
I posted this link before, but the first photo on
http://www.rogerhalstead.com/ham_files/tower.htm shows how I guyed mine
and that is with the *stretchy* 3/16" nylon rope. You can purchase much
better/stronger/UV resistant rope (Dacron and Polyester) at the
RFConnection, Davis, The Wireman...and others for a fraction of the cost.
> 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...
And here I figured I was cramped for guy space. I miss living out in
the wide open farming country.
> DO I NEED TO GUY IT... really? (Yeah... I know
> an ounce of prevention...)
>
Although they do say you don't need guys, it's a really good idea. If
you get winds above 40mph I'd call it a necessity.
I mounted my AV640 at the end of the shop and guyed it back to anchors
screwed into the edge of the roof on two sides. The third goes to a
tree, or sometimes to a fence post or on occasion it gets tied to the NW
guy anchor for the tower. These guys have very little load on them even
in high winds. It's just the AV640 is "pretty flexible"<:-))
However! There is a big difference in requirements for support and
guying when mounting the antenna at 10 - 20' and 40'. At 40 feet the
top is nigh onto 70' off the ground and it gets a lot windier up there
than at 30 or 50 feet.
Next time I let mine down it's going to get a Lexan (TM) collar placed
where the guys are now. The collar will have holes for three guys. This
will let the guys "float". It's also going to get a current choke at the
base of the tuning unit.
> ANY IDEAS GREATLY APPRECIATED. I WOULD LIKE TO GET
> THIS UP SOON...
>
> I admit to obsessing, but my big vertical sustained 60 mph winds
>
There was a lot of damage in our area, but the antennas came though with
flying colors. <:-))
> 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.
>
>
73 and good luck,
Roger (K8RI)
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