[TowerTalk] Hy-Gain AV-640

[Roger (K8RI)]

Richards wrote:
> Thanks Roger...   you must have received harder wind than
> the weather service reported.  Here they said gusts were up
> to 57 mph and at the Mt Pleasant airport they said at 5:55 SW
> winds of 37 mph with Gusts of  48 mph.   I am sure that is way
> off because there was WAY more wind that 48 mph on the
That wouldn't be far off from what we had around that time of day.  The 
real surprise was the one storm was moving at 135 to 145 mph from S of 
GR to right over us and beyond, yet the surface winds associated with it 
were fairly mild. The heavy winds we received were probably around 4:00 
AM when the front went through.  It put many trees and power lines down. 
We had about 5 or  6 electrical blips that just barely caused the lights 
to flicker.  The radios were unaffected even though they use 
microprocessors. Apparently the caps held enough charge long enough they 
didn't get confused.  However I did discover the UPS on my quad core 
computer  isn't large enough to keep it running.  It  crashed with the 
blip. This one was unaffected.

There are still a lot of homes over here without power, and the road out 
front is still closed with downed power lines about a mile to the West 
of us. Fortunately there is only one tree close to any of the antennas 
and we did some major surgery on that last summer. We'd need a major 
wind out of the NNE to turn that one into a problem  as it could just 
reach the guys for the big tower right up next to the NW guy anchor post. 
> front as you suggest - here as there, also, I am sure.   I am
> often amazed at how much variance there is between weather
These winds vary considerably over relatively short distances.  I've 
seen straight line winds of nearly 100 mph take down trees and 
buildings. One such even destroyed a tied down airplane. It actually 
pulled the tiedowns out of the ground and put shoulders in the wings 
where the struts attached. The "straight line" wind that was that 
strong, left a path of damage less than 100 yards wide.

Winter storms as seen from the air can be impressive.  It looks like 
some one took a giant paint brush and slopped white paint across the 
landscape. There may be a path of deep snow a mile or two wide and then 
bare dirt for a few miles followed by another swath of snow a couple 
feet deep.
> service figures and those of the other sources - which vary
> less among themselves - Govt deflation....I guess.
Well, you could say the weather is as indecisive as our congress critters.
>
> Interesting comments on the two pipe mast arrangement.
The nice thing about the two pipe arrangement is it can be scaled into a 
tall, fold over, crank up, and/or rotating mast using structural steel 
tubing. The only drawbacks are it gets heavy and expensive in a hurry as 
you scale up. Also the stresses scale up even faster than the height so 
it takes a bit a engineering to build something beyond about 60'.  
Common sense and extra strength can get you about that far, but beyond 
there you really need to know with some precision, the loads and yield 
strengths from base to top. 
> I am getting warm to the notion of a tip over arrangement, rather
> than standing on the roof.  I am thinking I could build a 15-17 foot
> tilt over water pipe that brackets/braces against the rafters/eaves
I'm not a real fan of water pipe as it tends to be on the soft side, is 
heavy for the size and strength, and bends relatively easy compared to 
other materials. Also, although galvanized it will rust if care is not 
taken which is also one of the problems with structural steel tubing.  
However a couple of good coats of good paint can do wonders.
> and puts the antenna up about 5-6 feet over the sloping roof.
>
but 5 or 6' above the roof = maybe 20 to 30 feet above ground and that 
is still in the realm where the structure doesn't have to be massive or 
bust the bank account.  I need to start making the rounds of the 
auctions and clearing houses looking for a good size lathe and floor 
mill as I have some ideas for projects and I'd really like to build a 
crank up, fold over, rotating mast heavy enough to take a large 
tribander.  I'd love to build a 100' crank up, rotating mast that'd take 
a 4L shorty 40, but the weight and cost of the materials is breath 
taking. Then you get into the raise and lower mechanism, latches, 
safety, and reliability. You are getting into 20 foot sections that are 
8", 10", 12" and 14" with half inch walls.  That's in the territory 
where it takes heavy equipment, or specialized equipment just to move 
the sections.  Then it'd  be nice to have them hot dipped galvanized.

Of course the whole thing needs to set on a thrust bearing (wheel 
bearing/taper bearing) strong enough to hold all the weight and may be 
6" , 8", or even larger in diameter.  That'd be a good one to look for 
in the junk yards that might have collected some old, heavy equipment.

Ah, well, I guess I can keep dreaming.<:-))

> I checked your web page and did not find a photo specifically
> of the two pipe arrangement you used.  Did I miss it?
>
That's one of the things of which I don't even have a photo.
> As for guy ropes, your mention of a 120° split means I could use
> only three ropes, and, perhaps, I could tie it off to two sides or 
> corners
> of the roof, and put one on an 8 or 10 foot high mast or pole
> I could stand next to a tree that is located about the angle
With Nylon and Poly rope you can even use the tree, just don't wrap the 
rope tightly all the way around the tree.
>
> and distance away, and still avoid the neighbor kids and the
> lawn service getting tangled up in it, and still provide a support in
> that direction.  I had originally wanted to work with a four point
> guy system, but maybe a three .is sufficient.
Generally three is whats used and it's one whale of a lot less work to 
adjust than 4.
>
> Thank you for the detailed information.
> GOOD NEWS YOUR ANTENNA SURVIVED THE WIND
> WITH NO PROBLEMS  - I think the wind was much stronger
> than reported by the weather service.
Bout 4:00 AM when the front went through the house was just shaking.

73

Roger (K8RI)
>
> Happy trails and 73.    ----  Richards - K8JHR ----
> =============================================
>
>
>
>
> Roger (K8RI) wrote:
>
> When the front went through we were looking at 40 to 50 mph winds
>> with gusts well in excess of 60-65.
>
>> That's pushing your luck without guys.
>
>> 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. 
>
>> I should add the AV640 is VERY sensitive to nearby antennas on any of 
>> the bands it operates on.  
>
>> The manual has a section on this, but it states, 5 ' minimum.
>> The drooping is not a problem
>
>> The antenna is like a "wet noodle" in the wind, although it can 
>> handle 30mph without damage.
>
> should be guyed at *roughly* 120 increments, but you
>> can take a lot of license/variance in that.
>
>> Although they do say you don't need guys, it's a really good idea. 
>> you get winds above  40mph I'd call it a necessity.
>
>
>