Hi Lee,
Bravo! For championing a wider discussion of ham related ideas.
However, as has been pointed out to me numerous times (I think they
were pointing to True North).... that when we get too far afield of the
primary mission of the reflector... lots of "non-interested" types get
their noses out of joint. After all... "they have rights too!"
Oh well. I do see both sides of this issue. Those of us who read the
reflector day in and day out see so much of the same stuff show up that
it almost begs to save one's sanity to read something interesting or
controversial or different for a change. Of course I'm partial to
topics about finding True North and using streaming toilet paper to
provide obstruction warnings for low flying airplanes.... but so-called
"sane" people can only take so much of that.
Anyway.... we needed a breather once in a while (including a "warning")
and then things will be back to normal again.
As for your roof mounted tower problem....
I've looked at the (I think it was the Glen Martin) aluminum towers and
after studying them carefully, have concluded that it would be pure
child's play to make your own. All you need is the aluminum angle
material, a drill and a hacksaw.
Since the aluminum angle stock may be expensive... you could easily
substitute iron. Now, my tripod roof tower (originally made by South
River Products... now out of business), is made from tubular steel.
Tubular steel may not be all that easy to find.... but I'll bet that
3/4" water pipe would do just fine. Sure it would be a lot heavier
than aluminum or iron angle stock... but I'd bet dollars to donuts it
would be a whole lot stronger and vastly cheaper. [I can just hear the
teeth gnashing by the ultra-conservative among us about using "water
pipe" for anything except water!]
Then again, we're not talking about a tower that is going to carry a
monster antenna or a stacked array. A TA-33 such as I'm using does
next to nothing to stress my roof tower who's tubular steel legs and
cross braces are far skimpier than heavy gauge TV masting. Note that
the ends of the tubing are clamped shut... such as might be done in a
good heavy duty vise or with a sledge hammer.
Should you decide to go the water pipe route.... I'll bet that a ten
foot roof-mounted tower could be homebrewed for well under $60
including all the materials... including stainless steel bolts, nuts
and washers. I truly believe my roof would be ripped away before any
damage occurred to the tower itself. Most of the trick is getting the
tower properly secured to the roof. I'd recommend designing the thing
to hold the rotor inside the tower....preferably at the bottom e.g..
closer to the roof, and using a thrust bearing at the apex to carry the
load of the antenna. Unfortunately, mine is just the opposite.
The biggest problem I have with this entire set-up is that running 1500
watts on 20m 15 feet above the bedrooms gives me goose bumps. I
haven't done the calculations yet (or much operating in this
configuration with anyone upstairs... but something tells me it's not
a good idea. I'll have to go to the ARRL website and run the
calculations to know for sure. (I'm almost afraid to do it... but I
know I must.)
Good luck with your project.
73,
Roger, K2JAS
Morganville, NJ
Just about half-way between NYC and Philly!
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