When I bought my 2" 4130 about 23 years ago, I had to take what was in
stock - 22'. To increase the length, I added a 12' piece of 1.5". Both were
.25" wall. I tried fitting the 1.5" inside the 2". It wouldn't quite fit. I
had to do some filing to get it to slip in a little. Then I took a large
sledge hammer and hammered the two pieces together so that there was 2' of
the 1.5" inside the 2".
Then I drilled a hole through both. Used a taper pin reamer and hammered in
a taper pin.
I have the rotor 8' down from the top of the tower. I insert the 2" end
inside the tower. This gives me 24' above the tower. Over the years I have
had several different types of HF antennas hanging off this mast. Never had
a problem.
The mast is on an 80' Rohn 45 tilt over tower. So, no trouble getting to the
top antennas.
The mast sure flexes in high wind, but nothing has broken, yet. Don't know
if what I did meets good mechanical design, but it has worked fine.
For comparison to antenna loads, I have a C31XR at 82', a MAG240N at 90' and
a WARC7 at 103'.
N2TK, Tony
-----Original Message-----
From: towertalk-bounces@contesting.com
[mailto:towertalk-bounces@contesting.com]On Behalf Of Bob Johnson
Sent: Monday, August 04, 2003 20:38
To: wi8w
Cc: Towertalk@contesting.com
Subject: Re: [TowerTalk] mast recommendation
Maybe you are asking for a little too much !!!
I seem to remember that 21 Feet was a "Standard Length" for
pipe and tubing !!!
Try calling a supplier and asking " What is the Standard Length"
for 2 inch OD 1/4 inch wall 4130 pipe or tubing.
Might be a few feet shorter, but many $$$ cheaper !!!
73
Bob, K1VU
FN42ma
At 07:49 PM 08/04/03 , wi8w wrote:
>Living in Grand Rapids, MI with a population of somewhere near 1 million
>people you would think that finding a length of pipe for a mast would be a
>easy task...not so.
>
>I have spent the last week calling every steel dealer both in new and used
>steel for a chunk of 2 inch OD 1/4 inch wall 4130 pipe about 24 feet long.
>Did I find anyone who could supply it?...nope. All said it was special
>order and they could not guarantee 24 feet. best they could do is
something
>random betweek 17 and 24 feet Special order meant that not only did I have
>to pay for the pipe (around $16 a foot) but I would have to pay the
shipping
>(about $300 for a 24 foot length). They all said that I could buy two
>pieces (and pay the shipping) and weld them together to make the 24 feet.
I
>am not a big fan of nor do I know how to weld anything short of a resistor
>to a circuit board.
>
>Anyone have any suggestions for a substitute at about a 24 foot length? I
am
>stacking the following:
>
>2M/440 vertical
>19 element 440 beam
>20 element 2 meter twist antenna (10 vertical and 10 horizontal)
>5 elements on 6 meters
>A4S tribander
>
>in that order top to bottom. Yep it is going to be tight and the first 10
>feet of the mast will be inside the tower
>
>2 inch OD seems to be the biggest I can go given the size of the thrust
>bearing (TB-3) on the tower.
>
>thanks
>
>73
>
>Thom WI8W
>
>
>
>
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>See: <http://www.mscomputer.com/>http://www.mscomputer.com for "Self
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_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any
questions and ask for Sherman, W2FLA.
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