Hi Dick,
One of my towers is a US Tower MA550MDP on a rotor base. The azimuth rotor is,
of course, in the base, and there is an elevation rotor at the top of the lower
(outside) tube. It has a 10' M**2 crossboom with 3.1 sq. ft. (and growing) of
satellite antennas plus feedlines and other associated cables. At the top of
the tower, on a 6' mast, there was a HyGain TH-5DX (which is currnetly being
refurbished... temporary replacement a TH-3 mk III). The TH-5 is 6.4 sq. ft.
and I'm probably going to replace it with a TH-7 AND add a taller mast with a
small Yagi on top (I'm debating between 6 meters, 2 meters and TV). I have no
doubt it will take it as long as the motor drive doesn't fail right before a
storm (I have battery power and a 2.5 kw inverter so a power outage doesn't
worry me. A small portable generator would give the same insurance.).
When the tower is up it sways quite a bit in a big wind (we don't get any
really big winds in this particular spot, 50 mph in my location would be a huge
storm) but when it is down it is a real pussycat. Below the trees as in your
location. The key is bringing it down. If I thought I might accidentally
leave it up in a big storm, I would stay where I am (under 10 sq. ft.). I'm
willing to take a chance on overloading it somewhat because I know when it's as
simple as flipping a switch I have no excuse for not bringing it down. I do
preventative maintenance and I'm willing to take a chance on the remote
liklihood of a simultaneous mechanical failure and big wind storm.
Bottom line is I love it. I rotate my tribander simultaneous with my satellite
Yagis which is great for working the low passes of the RS birds. I wish it was
the MA770MDP instead, but they are very scarce on the used market (all my
towers and most of my antennas are second hand or homebuilt). I wouldn't
hesitate to put the same or even larger antennas on the 770. When it is
cranked down it is only a few inches taller than the 550 and it's a whole lot
beefier. The operative words (again) "when it is cranked down."
Go for it! Put up the big one. Most unlikely it will stick in the up
position, more likely it would stick in the down position as that is where it
will spend most of it's time. If you have a lot of power outages, get a
generator or some sort of back up power (hams should have that anyway, right?).
What does the xyl think of it? Well, it's in the front yard.
I used to live in SD (that's South Dakota, not San Diego) and we got a lot of
ice on antennas there. If you are in a similar situation I think I would favor
the TH-7 over the KT-34XA. In fact, I do even out here (SF bay area), but
that's strictly a personal opinion. I know the KLM is a great antenna too. A
good ice storm, by the way, could very likely cause one of these towers to
stick until it melted. The belt slips when there is an excessive load on the
motor drive. That's intentional, and keeps major disasters from happening if
the limit switches fail. But then you would have it down BEFORE the ice storm
started, RIGHT???
I'm going to be in CT for over a month next late summer/fall (1998). Maybe you
can show me how it turned out? Good luck.
73 - JC,k0hps@amsat.org
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