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[TowerTalk] MARC question

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Subject: [TowerTalk] MARC question
From: (JC Smith) (JC Smith)
Date: Fri, 30 May 1997 12:25:38 GMT
Hi Steve,

I've been having fun playing with the MARC software, trying all sort of what-if
situations.  Nice program, thanks (& your check is in the mail).

I assume antennas can be added to the database by simply editing the
antennas.dat file with any text editor.  Is this correct?

Second question.  I already own a US Tower mast, their # M-20R.  You probably
already know this, but it is a 20' Galv. steel mast, 2" OD, .120 wall with an
insert in the lower half, giving the lower half a .250 wall thickness.  Weighs
70 lbs.  Any suggestions on fitting this into the results I get from the MARC? 
I don't see any info. in their catalog on yeild strength, but as it is 2" OD
tube with the listed wall thicknesses I would think it is more than just galv.
pipe.  I have a call in to UST to try to get more info, but perhaps you already
know what it is.

Where I would like to use it is on top of a rotating tower (MA-550MDP with
freestanding rotor base).  It would only go approx. one foot into the tower,
leaving 19 ft. of useful mast above it.  I would like to install a TH-7DX at
the mid point of the mast (or higher) and a small antenna at the top, a decent
TV antenna so I can tell the cable company to kiss off (any TV antenna

Actually, I suspect this should be plenty strong (I'm in a very sheltered
location and this tower is motorized so it is down any time the wind is blowing
or we are away.)  However, what concerns me more is the ability of the mast to
support the antennas and itself while it is being tilted up from the
horizontal, the ability of the top of the tower to support it (it actually goes
less than a foot into the tower) and the ability of the raising fixture (US
Tower MAF-550) to support the extra load of the mast and antennas during the
raising process.  I can help it along for the first few degrees of elevation
(where the angle is the worst) but it soon gets out of reach.  I'm hoping to
avoid the necessity of erecting a temporary tower behind it to use as an
assistant raising fixture for the mast.   I have a similar question about
tilting up another stack, but I'll save that for later.

I should also mention that I have an elevation rotor, crossboom and satellite
antennas monuted down low on the tower (on the lowest, outermost section of
tube).  These are quite small, but I mention it because I'm frequently
experimenting and playing with them which requires tilting the tower over.  I
really don't want to have to rent a crane every time I do it.

Your (or anyone in the group) advice would be appreciated.

73 - JC,

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