30 foot mast....what do you use?

[Joe K7JOE]

Hi,
Am putting up an antenna support mast to hold a smaller (ham 4) rotor
and 3
element tribander (TA-33 Mosley). I am in need of a support structure
to hold up the aluminum. Cant find a light duty tower, so, going
with a supported mast structure. Key points:

1. Mast will be supported at the base by a cement block/bracket.
Thus, downward force will be well supported by the earth.

2. Mast will be supported horizontally and vertically by a 27 foot
brick
chimney and the stainless steel chimney straps/brackets in at least 3
places, at the base, 15 foot, at the 22 foot, and at the 27 foot level.

3. The rotor is held to the top of the mast by a "bottom mast support"
that
is common to the telrex/hygain/CDE/CDR rotors.

4. No additional guying will be available.

5. Antenna is a 3 element tribander, weighs about 40 LBS. Using thick
walled
aluminum mast from the rotor to tribander, which is rugged yet light
weight.

Upon looking at the various pushup poles, I note most use 16 AWG for the
lowest section, then go to 18 AWG for upper sections. On the other
hand,
Radio Shack sells 10 foot swag ended mast that is 18 AWG. I bought 3
sections, planning to put them together to form my 30 foot mast.
But am now thinking that is too light a duty mast (even if supported
along the the entire mast length using the chimney as structural
support).

So, what are my other options for antenna masts? Thought about getting
some fence post masts, say, one 2 inch diameter, and then go to one 1
7/8 inch
diameter, then one 1 5/8 inch diameter ten foot lengths
and using stainless steel bolts to hold
the three masts in "telescoping" configuration with six or eight
inches overlap per section. This stuff is lots heavier
weight wise anyway, but not sure mechanically.

My main concern is that the very top of the mast will bend (being
supported
at 27 feet, leaves 3 feet exposed, upon which the rotor will go, and
then about
3 feet of aluminum heavy walled mast and then the tribander. So, there
is conisderable stuff "above" the 27 foot final support. We're
talking
probably 30 pounds of rotator, and 50 pounds for antenna/mast.
Remember that
this stuff is all supported vertically since the mast extends all the
way
to ground and rests there in a bracket. Mostly concenred with
horizontal
momentum.

Thanks,
Joe

[Daniel nicholson]

How abt using 3 sections of RIDGED 1 1/2 inch conduit? Not EMT but ridge
type. I use it for masting all the time...forget abt the tapering u dont
need it...

73 Dan
Joe K7JOE wrote in message <388CBB09...@yahoo.com>...

[Dennis]

I'm hoping to push the "envelope" even further than you are and have
been asking questions here for a couple of weeks. If you have a good
news-server, go back a bit, or search on Deja.Com. The guys here have
given me much to think about and work on!

Good luck!

Dennis

[Floyd Sense]

I trust that your chimney is either pretty new, or is in excellent
structural condition. If not, you will soon learn how expensive a brick
chimney is to replace.

K8AC
Floyd Sense - Angier, NC

Joe K7JOE <K7...@yahoo.com> wrote in message
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