> Has anyone had experience with the US Tower MARB55? Specifically a couple
> questions:
>
> 1. Has anyone ever tried to build a homebrewed crank-up winch? Seems like
> the cost of the US Tower unit is pretty steep! Like another tower....
> 2. Has anyone ever had one fail in a strong wind? And how much wind load /
> wind speed did it take?
> 3. How do you like it? What problems have you had?
> 4. Considering a two or three element tri-band Circular Quad on top. A lot
> of work to build tooling and antenna, don't know if I'll get it
> built, might
> settle for a traditional quad. Anyone put a quad on the MARB55?
Tom,
I have an MA770-MARB, not exactly the same but similar enough for me to
comment:
1. This isn't your typical homebrew project. Unless you really know your
engineering, metalurgy and welding, I wouldn't recommend trying to build
your own motor winch. Besides, I suspect it would cost you an appreciable
percentage of what U.S. Tower charges.
2. Mine hasn't failed (yet...) Most of the failure stories I've heard
involved very old and rusted cables that snapped. I've heard about one
crankup failure due to wind (another brand and another style.) That was a
case of an excessively loaded tower in unexpectedly high winds. What I can
tell you is that the tower sways A LOT in strong winds. You should (must)
follow the manufacturer's specs. They used to be 10 sq ft max at 50 MPH, but
I understand that they've been upgraded to 10 sq ft at 70 MPH (no change in
tower construction, just a change in the math used for the calculations.) I
have a 9.5 sq ft TH-7 on mine and would NEVER leave it up in winds over 30
MPH (one look at it swaying in the breeze and you would come to the same
conclusion!) The tower might make it to 50 MPH, but I don't want to find
out! However, cranked down to 50', I'm comfortable up to at least 40 MPH
(still, it goes down when the wind gets over 35 MPH.) I'd say the antenna
would probably break before the tower at that height. In your case, you'd
have to put it down to probably 30-35 feet to get the same effect. Note:
since the tower is 250 feet away, hidden behind trees, I have the remote
control package. It keeps me from getting lazy and not putting the tower
down.
3. I love the tower, but since there were no installation instructions, it
took a while to get it working properly, especially rotation. I also have a
50' guyed portable aluminum military mast (massive 5" diameter tubing.)
Personally, I like that tower better because nothing short of a hurricane is
going to knock it over. However, my wife hates it and has come to appreciate
the retracting MA-770 much more than when it first went up :-)
4. The type of antenna doesn't matter -- just the windload. As long as it's
under 10 sq ft, no problem. Since your quad will no doubt require more
maintenance than a yagi, the tower's tiltover fixture might be advisable.
73, Dick WC1M
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